WO2024032970A1

WO2024032970A1 - Subfloor panel and subfloor panel system

Info

Publication number: WO2024032970A1
Application number: PCT/EP2023/068018
Authority: WO
Inventors: Edwin Lingg
Original assignee: Li&Co Ag
Priority date: 2022-08-12
Filing date: 2023-06-30
Publication date: 2024-02-15
Also published as: NL2032743B1

Abstract

The invention relates to a subfloor panel for use beneath a decorative floor covering, in particular a floating decorative floor covering composed of a plurality of decorative floor panels. The invention also relates to a subfloor panel system comprising a plurality of said subfloor panels according to the invention for use beneath a decorative floor covering.

Description

Subfloor panel and subfloor panel system

The invention relates to a subfloor panel for use beneath a decorative floor covering, in particular a floating decorative floor covering composed of a plurality of decorative floor panels. The invention also relates to a subfloor panel system comprising a plurality of said subfloor panels according to the invention.

The demand for rigid decorative flooring materials such as ceramic and masonry tiles and decorative floor panel has grown over recent years. These products are, among other qualities, durable, easy to maintain, and attractive. However, despite their numerous desirable qualities, these materials typically exhibit insufficient acoustic properties with regard to structure-borne sound transmission. Specifically, the noises generated by footfalls or other periodic impacts are readily transmitted to and beyond an underlying concrete or wooden construction floor.

Therefore, often an underlayment or subfloor is applied in between the construction floor and the decorative floor covering with the purpose to provide sound abatement for a room and/or to provide a moisture barrier between the construction floor and the decorative floor covering. An example of such a subfloor is a bulky roll of foamed polyethylene, polyurethane, polystyrene and polypropylene. These rolls typically have a standard width, wherein during installation the foam is unrolled and positioned onto the construction floor. Adjacent foam layer are typically connected by an adhesive tape. However, this known method is considered as rather impractical, laborious and time consuming. Moreover, the acoustic properties of these subfloors typically deteriorate in the course of time during the constant compression of the foam which affects the sound absorption capacity of these subfloors.

It is therefore a first object of the present invention to provide an improved subfloor system, in particular improved subfloor panel.

It is therefore a second object of the present invention to provide a more practical subfloor system, in particular a more practical subfloor panel. It is therefore a third object of the present invention to provide an improved subfloor panel which allows relatively easy and fast installation of a subfloor.

It is therefore a fourth object of the present invention to provide an improved subfloor panel having relatively durable acoustic properties.

At least one of these objects can be achieved by providing a subfloor panel according to the preamble, comprising:

- a top layer having a top surface and a bottom surface,

- a bottom layer having a top surface and a bottom surface,

- the top surface of the bottom layer being adhered to the bottom surface of the top layer such that the bottom layer is offset from the top layer in a direction of length and/or width, thereby leaving both the top surface of a marginal end portion of the bottom layer and the bottom surface of a marginal end portion of the top layer exposed, wherein a length and/or a width of the bottom layer is preferably less than a length and/or a width of the top layer, creating an optional gap between the bottom layer of the subfloor panel and a bottom layer of an adjacent subfloor panel, and wherein the top layer comprises:

- at a first top layer edge comprising a first coupling profile, and

- at a second top layer edge, preferably located opposite to the first top layer edge, comprising a second coupling profile being designed to engage i nterlocki ngly with said first coupling profile of the top layer of an adjacent subfloor panel in horizontal direction and/or vertical direction.

The subfloor panel according to the invention has a plurality of advantages. Subfloor panels are more practical to handle due to the limited size and weight compared to traditional foam rolls. Moreover, since the top layer comprises coupling profiles, adjacent subfloor panels can be interconnected without necessarily using tape and/or mechanical fastening means such as nails (which would affect the acoustic properties). This typically leads to a constant height of the subfloor while preserving the acoustic properties of the subfloor panels. Hence, the interconnectable subfloor panels are designed to realize a floating subfloor. The offset orientation of the top layer and the bottom layer stabilizes the eventual subfloor as adjacent subfloor panels will also support each other. Preferably, the top layer is oversized compared to the bottom layer. This will result in a gap formed in between bottom layers of adjacent subfloor panels. These gaps allow the top layers of adjacent subfloor panels to be positioned relatively tight to each other and prevent unwanted gap formation in between top layers of adjacent panels.

Moreover these gaps facilitate water drainage. The present invention is therefore in particular related to subfloor systems to be covered by a decorative floor covering. Hence, the subfloor systems do not require any decorative character and are therefore preferably free of any decorative layer and/or textured layer (embossing layer).

The subfloor panel according to the invention preferably comprises a top layer being composed of a single material layer. The single material layer does not have a decorative upper surface and can (therefore) be optimized for its purpose to support a decorative floor covering. Preferably, the top surface of the top layer defines the upper surface of the subfloor panel. Preferably said first and/or second coupling profiles are configured for establishing both a horizontal and vertical locking between adjacent subfloor panels, which is preferably free of play. Such a free of play coupling leads to a tight coupling between the subfloor panels, which are favourable to realize a stable subfloor, and which as such is favourable to durably install a decorative floor on top of this subfloor. Preferably, each of the first and second coupling profiles are configured for establishing both a horizontal and a vertical locking. Due to the nature of the coupling profiles according to the present invention, the time required for forming the subfloor may be significantly reduced, whilst at the same time maintaining a stable subfloor. The first and second coupling profiles make sure the interlocked panels may not, neither in vertical nor horizontal direction, easily disconnect under normal use. However, upon reversing the movement for locking the panels, it is preferably possible to disconnect interlocked panels which may provide even further advantages such as reuse and/or replace the subfloor panels. Since the first and second coupling profiles allow for a horizontal and vertical locking, the subfloor may be favourably assembled without using glue. An additional advantage of the horizontal locking is that adjacent subfloor panels will not, or significantly less, shift during the assembly of a subfloor. Hence, the subfloor composed of a plurality of interconnected subfloor panels may already provide a substantially stable partial subfloor without having to use the fixed world, such as walls of a room to stabilize the subfloor. Yet further, an advantage of the coupling profiles is that the subfloor may not only be placed on a floor, but may also suffice as a subfloor on a wall or even on a ceiling. In particular, it is preferred that the locking profiles are essentially free of glue or adhesive. In particular wherein the first and second coupling profiles are, at least in an engaged position, free of adhesive. Adhesive is preferably not applied, since adhesive is often applied prior to coupling, which may cause that during coupling some adhesive flows outside the coupling edges and dries. If the adhesive dries in such a manner that it protrudes from the top surface it is required to sand the subfloor which is rather cumbersome and therefore undesired (and unnecessary).

In a preferred embodiment the subfloor panel further comprises at a third top layer edge comprising a third coupling profile, and at a fourth top layer edge, preferably located opposite to the third top layer edge, comprising a fourth coupling profile being designed to engage i nterlocki ngly with said third coupling profile of the top layer of an adjacent subfloor panel in horizontal direction and/or vertical direction, and preferably in a vertical direction only for easy of installation. Preferably, the third and fourth coupling profile are of a different type compared to the first and second coupling profile. Preferably, the first and second coupling profile provide for a horizontal and vertical locking action, whereas the third and fourth coupling profile may provide at least a vertical locking and optionally a horizontal locking. Preferably, in the present invention locking of the coupling profiles may be understood as not merely obstructing, to this end it is preferred that click-profiles are provided which establish a click-connection which allows for locking the coupling profiles. Due to the coupling profiles provided in the present invention it is possible to ensure a better and more smooth top surface between coupled subfloor panels. This is of great importance for decorative floorings to be provided onto the subfloor. It greatly contributes to the efficiency for users such as craftsmen. In particular since a sanding action may not be necessary, as well as the user which is notified that subfloor panels are correctly installed by being noticed by a clicking sound of the first and second coupling profiles. Preferred embodiments of the third and fourth coupling profiles will be described below in more detail.

It may be preferred that at least one marginal portion, preferably all marginal portions are free of any adhesive. It is additionally or alternatively also imaginable that at least one marginal portion is provided with an adhesive, preferably a pressure-sensitive adhesive. Because of the nature of a pressure-sensitive, the subfloor panels are capable of being easily detached from one another without damaging the subfloor panels for ease of installation and/or replacement thereof.

Preferably, said exposed adhesive (if applied) on the marginal portion(s) are initially covered by a removable release film. This is typically a flexible sheet, preferably corresponding in size and shape to the marginal portion(s). It will be appreciated by those skilled in the art, however, that the size and shape of the release film may be varied. The release film may be made, for example, from any known suitable release material, such as a silicone coated paper, a plastic sheet, a polymer film, or other material that enables the release film to be quickly and easily removed from the adhesive surface during the installation of the subfloor panel.

Preferably, the top layer is, directly or indirectly, adhered to the bottom layer. Any suitable adhesive, such as a hot melt adhesive (thermoplastic adhesive), a pressure sensitive adhesive, or a structural and/or reactive adhesive, can be used. However, it is typically preferred to apply a thermoplastic adhesive, such as polyvinyl acetate, for this purpose. This latter allows easy (and clean) separation of the bottom layer and the top layer upon heating above a threshold temperature, such as 80 degrees Celsius. This facilitates recycling of the bottom layer and top layer. It is imaginable that at least one intermediate material layer (other than an adhesive layer) is present in between the bottom layer and the top layer. It is imaginable that the top layer is fused to the bottom layer, without using an additional adhesive. This latter can e.g. be realized by including a thermoplastic material in both the top layer and bottom layer which can be fused during a heating step. Preferably, the top surface of the top layer is essentially smooth and/or flat and/or planar. That is, preferably the top layer, in particular said top surface is free of interruptions and/or indentations and/or textures and/or large bevels. This may enable the top layer to form a good flat, and therefore equalized, supporting subfloor surface. It is in particular preferred that the top surface of the top layer is flat in the space that is spanned by the first and second coupling profiles. It is imaginable that the top surface of mutually connected (adjacent) panels continues substantially smooth. The latter may provide that, once a subfloor panel is connected to an adjacent subfloor panel, an even supporting surface may be established. It is preferred that the top surface of the top layer of the subfloor panel has a height difference with a top surface of an adjacent subfloor panel of less than 0.5 mm, preferably less than 0.1 mm, in particular less than 0.05 mm, ideally essentially level (flush). Application of the first and coupling profiles, configured to realize a horizontal and vertical locking effect in between coupled subfloor panels, are well suitable to realize the desired substantially flush orientation of the adjacent top surfaces of adjacent subfloor panels.

The bottom layer is preferably composed of a single material layer. The material composition of the bottom layer may be identical to the material composition of the top layer. It is also imaginable that the material composition and/or properties of the bottom layer are different from the material composition and/or properties of the top layer. Preferably, at least a part of the bottom surface of the bottom layer defines the bottom surface of the subfloor panel. Preferably, the entire bottom layer is a single and/or continuous layer, at least in a width direction of the panel. It is imaginable that, seen in cross-sectional view, the bottom layer stretches from left to right essentially without interruptions. This allows the bottom layer to provide a good support and flatten out any inconsistencies or relief in the floor. However, it is also imaginable that the bottom layer is provided with one or more cavities and/or through-holes, preferably arranged in a pattern, to save weight and preferably to improve the acoustic dampening properties.

It is imaginable that at least a part of the bottom surface of the bottom layer is covered by a backing layer, such as a cork layer and/or a foamed layer. Preferably, said backing layer is at least partially composed of at least one material chosen from the group consisting of a: preferably low density, foamed layer of ethylenevinyl acetate (EVA), irradiation-crosslinked polyethylene (IXPE), expanded polypropylene (XPP), expanded polystyrene (XPS), a non-woven material and/or a woven material, preferably with fibres, such as made from natural fibres, like hemp or cork, and/or a recycled and/or recyclable (thermoplastic) material such as PET. The backing layer is often applied to improve the acoustic panel properties and/or to provide more comfort to the subfloor panel to improve the user experience. It is also imaginable that at least a part of the bottom surface of the bottom layer is covered by a backing layer which is resilient. Due to such a resilient backing layer, the bottom surface may conform to an unevenness of the floor to be covered by the subfloor. Additionally, it may contribute to a better distribution of pressure since a better contact surface may be formed.

It is imaginable that the top layer and/or the bottom layer is at least partially composed of at least one material chosen from the group consisting of: bamboo, hemp, wood, wood fibres, MDF, LDF, HDF, and plyboard. It is also, additionally or alternatively, imaginable that the top layer and/or the bottom layer is at least partially composed of at least one material, preferably at least one additive, chosen from the group consisting of: mineral material, like magnesium oxide, gypsum, concrete, clay, talc, chalk, wood, graphene, graphite, glass, cement, magnesium oxide, magnesium hydroxide, rice, and/or calcium carbonate. It is also, additionally or alternatively, imaginable the top layer and/or the bottom layer is at least partially composed of at least one polymer material, preferably at least one thermoplastic material, more preferably at least one thermoplastic material is chosen from the group consisting of: PVC, PET, PP, PS, thermoplastic polyurethane (TPU), PE, in particular MDPE and/or HDPE; and combinations thereof. Thermoplastic material may be used in foamed state and/or unfoamed state. Preferably, the bottom layer and/or the top layer is/are rigid (composed of a rigid material) or semi-flexible. Preferably, one or more additives, such as a the abovementioned additives, are incorporated in a polymer matrix, in particular thermoplastic matrix, preferably selected from one or more of the above mentioned thermoplastic materials. Optionally, the bottom layer and/or top layer may comprises at least one reinforcement layer, such as a woven or non-woven glass (fiber) layer, which may be embedded into a thermoplastic material (if applied) of the bottom layer and/or top layer. It is imaginable that the top layer and/or the bottom layer is/are at least partially composed of a mineral material, preferably enriched with fibers, such as fiber cement, gypsum, and/or magnesium oxide.

Preferably, the top layer and/or the bottom layer is at least partially composed a mixture of virgin and recycled polymer material. Preferably, at least a fraction of the polymer used may be formed by recycled thermoplastic, such a recycled PVC or recycled PU. It is conceivable that a mix of virgin and recycled thermoplastic material is used to compose at least a part of the core The top layer and/or the bottom layer is/are at least partially composed of a water- resistant material. Such a material, of which examples are included in the lists above, make the top layer and/or the bottom layer unsusceptible for swelling, shrinking, and/or warping upon wettening.

Preferably, the first coupling profile and the second coupling profile are configured such that two of such subfloor panels can be coupled to each other by means of a turning movement and/or by means of a vertical movement.

It is often preferred that the panel comprises at least one third coupling profile and at least one fourth coupling profile located respectively at a third top layer edge and a fourth top layer edge. Preferably, the third coupling profile and the fourth coupling profile are configured such that two of such panels can be coupled to each other by means of a turning movement and/or a linear movement, such as a horizontal movement, and/or a sliding movement.

In a preferred embodiment, the first coupling profile and/or the third coupling profile comprises: an upward tongue, at least one upward flank lying at a distance from the upward tongue, an upward groove formed in between the upward tongue and the upward flank wherein the upward groove is adapted to receive at least a part of a downward tongue of a second coupling profile of an adjacent panel, and preferably at least one first locking element, preferably provided at a distant side of the upward tongue facing away from the upward flank, and wherein the second coupling profile and/or the fourth coupling profile comprises: a first downward tongue, at least one first downward flank lying at a distance from the downward tongue, a first downward groove formed in between the downward tongue and the downward flank, wherein the downward groove is adapted to receive at least a part of an upward tongue of a first coupling profile of an adjacent panel, and preferably at least one second locking element adapted for co-action with a first locking element of an adjacent panel, said second locking element preferably being provided at the downward flank.

Preferably, the first and second coupling profiles are configured to realize a droplock coupling, wherein the first coupling profile holds or secures the second coupling profile and preferably vice versa. To this end, it may be favourable that at least a part of an inside of the upward tongue, facing the upward flank, is upwardly inclined towards the upward flank and/or that a least a part of the inside of the downward tongue, facing the downward flank, is downwardly inclined towards the downward flank. Such a system is also referred to as a closed-groove system, wherein each groove of a tile panel holds or secures a complementary tongue of an adjacent tile panel, which results in a horizontal and vertical locking effect. An inverted embodiment, an open-groove system, is also imaginable in this case. The one or more first locking elements and the one or more second locking elements may further improve the mutual locking of interconnected tile panels.

Preferably, the first locking element comprises a bulge and/or a recess, and wherein the second locking element comprises a bulge and/or a recess. The bulge is commonly adapted to be at least partially received in the recess of an adjacent coupled panel for the purpose of realizing a locked coupling, preferably a vertically locked coupling. It is also conceivable that the first locking element and the second locking are not formed by a bulge-recess combination, but by another combination of co-acting profiled surfaces and/or high-friction contact surfaces. At least one of the first locking element and second locking element preferably makes integral part of the respective coupling profile. However, it is also imaginable that at least one of the first locking element and second locking element is at least partially formed by a separate component, such as a resilient locking strip, in particular a resilient polymer locking strip.

In the abovementioned embodiment, it is imaginable that the first coupling profile (and/or third coupling profile) and the second coupling profile (and/or fourth coupling profile) are configured such that in coupled condition a pretension is existing, which forces coupled panels at the respective edges towards each other, wherein this preferably is performed by applying overlapping contours of the first coupling profile (and/or third coupling profile) and the second coupling profile (and/or fourth coupling profile), in particular overlapping contours of downward tongue and the upward groove and/or overlapping contours of the upward tongue and the downward groove, and wherein the first coupling profile (and/or third coupling profile) and the second coupling profile (and/or fourth coupling profile) are configured such that the two of such panels can be coupled to each other by means of a fold-down movement and/or a vertical movement, such that, in coupled condition, wherein, in coupled condition, at least a part of the downward tongue of the second coupling profile (and/or fourth coupling profile) is inserted in the upward groove of the first coupling profile (and/or third coupling profile), such that the downward tongue is clamped by the first coupling profile (and/or third coupling profile) and/or the upward tongue is clamped by the second coupling profile (and/or fourth coupling profile).

It is imaginable that the first coupling profile is configured to co-act with the second coupling profile as well as with the fourth coupling profile, and that the third coupling profile is also configured to co-act with the second coupling profile as well as with the fourth coupling profile. It is imaginable that the first coupling profile and the fourth coupling profile are identical and/or that one of the first coupling profile and/or second coupling profile is identical to one of the third coupling profile and/or fourth coupling profile. In particular it is preferred that at least two coupling profiles at adjacent subfloor panel edges are identical, preferably the female coupling profiles. This may allow the subfloor panels to be interconnected in different orientations. Hence, a second subfloor panel may be connected with a short edge to a long edge of an adjacent first subfloor panel, or the other way around. This may allow for an even more stable subfloor since it provides more stability compared to the more standard stretcher bond or header bond or English bond or Flemish bond connection.

In an embodiment of the panel according to the invention, the first coupling profile and/or the third coupling profile comprises: a sideward tongue extending in a direction substantially parallel to the upper side of the core, at least one second downward flank lying at a distance from and/or connecting to the sideward tongue, and optionally a second downward groove formed between the sideward tongue and the second downward flank, and wherein the second coupling profile and/or the fourth coupling profile comprises: a third groove configured for accommodating at least a part of the sideward tongue of the third coupling profile of an adjacent panel, said third groove being defined by an upper lip and a lower lip, wherein said lower lip is optionally provided with an upward locking element, wherein the third coupling profile and the fourth coupling profile are configured such that two of such panels can be coupled to each other by means of a turning movement and/or linear movement and/or sliding movement, wherein, in coupled condition: at least a part of the sideward tongue of a first subfloor panel is inserted into the third groove of an adjacent, second subfloor panel, and wherein, if applied, at least a part of optional the upward locking element of said second subfloor panel is inserted into the optional second downward groove of said first subfloor panel.

It is conceivable that each first coupling profile and each third coupling profile is compatible - hence may co-act and interlock - with each second coupling profile and each fourth coupling profile. This may also apply in case interlocking coupling profiles do not have a completely complementary shape.

In a preferred embodiment, at least a coupling profile, and preferably all coupling profiles, is/are at least partially formed by the top layer and thus make integral part of the top layer.

The width of the (preferred) gap formed in between the lower layers of adjacent subfloor panels, in coupled condition, is preferably substantially constant along facing edges of lower layers of said coupled subfloor panels. Preferably, the width of the gap formed in between the lower layers of adjacent subfloor panels, in coupled condition, is situated in between 1 and 10 mm, preferably 1.5 and 5 mm. This prevents abutting of adjacent bottom layers and moreover could lead to sufficient water drainage properties. Preferably, at least a part of the gap formed between the lower layers of coupled panels extends in parallel and/or perpendicular to the longitudinal direction of the panel. The gap formed in between three interlocked subfloor panels is preferably substantially L-shaped.

Preferably, at least one, and preferably each marginal end portion, is substantially L-shaped. This typically requires an offset orientation of the top layer with respect to the bottom layer in both length direction and width direction. Preferably, the length difference between the bottom layer and the top layer is situated in between 1 and 10 mm, preferably in between 1 and 6 mm. Preferably, the width difference between the bottom layer and the top layer is situated in between 1 and 10 mm, preferably in between 1 and 6 mm.

Preferably, a width and/or an offset distance of at least one marginal portion, preferably each marginal portion, is situated in between 2 cm to 20 cm, preferably in between 5 cm to 30 cm, preferably in between 2 cm to 20 cm, more preferably in between 4 cm to 10 cm, most preferably in between 8 cm to 10 cm. This relatively large offset distance is preferred to equalize - even larger - imperfections of the underground in a relatively good manner. Hence, the large offset distance stabilizes mutually interconnected subfloor panels in a desired flush (level) orientation, which as such leads to a desired stabilization of the composed subfloor. An additional benefit of the marginal portions is that they provide for a stable subfloor which reduces the wiggling of the subfloor panels. It has in particular been found that a width and/or an offset distance of at least one marginal portion between 5 to 10 cm, more preferably 8 to 10 cm provides significant support for at least one coupling profile, which may reduce the risk of breaking of coupling profiles. Additionally the marginal end portions allow for reducing or obstructing a rotational freedom around an axis defined by at least one coupling profile. That is, if two adjacent panels are coupled, and a weight or force, for example exerted by a foot of a human or animal, is exerted onto the coupling profile, this typically causes the panels to mutually rotate a bit with respect to each other around the coupling profile axis. At least one marginal portion, in particular a marginal portion situated below said at least one coupling profile may distribute the weight and/or force and prevent the panels from rotating with respect to each other. Thus, the marginal portion contributes to the overall stability of the subfloor panel. Preferably the ratio between the thickness of the subfloor panel and the width of at least one marginal end portion lies in between 1 :5 - 1 :75, preferably in between 1 :5 - 1 :40. Yet, ratios between 1 :3 - 1 :5.5 or 1 :2 - 4, or a combination of these values or other values based on disclosed panel thicknesses and widths of marginal end portions.

The subfloor panel thickness is preferably in between (and including) 4 and 40 mm, more preferably between (and including) 4-20 mm, in particular in between (and including) 10-13 mm. It will be appreciated by a skilled person that other thickness such as 12 mm, 18.6 mm, 30 mm, or 40 mm may also be conceivable. Typically, the bottom layer and/or the top layer is/are substantially rectangularly and/or oblong shaped. Preferably, each the both the top layer and the bottom layer has an oblong rectangular shape. Preferably, the first and second coupling profiles are located at opposing long edges of the top layer, while optional third and fourth coupling profiles are preferably located at opposing short edges of the top layer. Preferably, an upper edge region of at least two edges, preferably all edges, of the top layer is proved with a bevel or other chamfer and/or a square corner. These bevels and/or other chamfers may be small, and may for example have a total bevel width of less than 0.5 mm. These small bevels and/or chamfers are also referred to as microbevels and/or microchamfers. Typically, a square corner is preferred since this may allow for forming a substantially continuous top surface. However these are hard to produce without material at the edge curling upwardly, which may cause (even a little bit) disruptions in the smoothness of the top surface. Such disruptions require a sanding action of the floor since otherwise these upwardly curling portions may be noticeable through a decorative floor. The bevels and/or chamfers are preferably less than 0.25 mm in width, in particular as measured from the start of the bevel to the closest panel edge. Preferably, said bevels or other chamfers are less than 0.1 mm. Two facing bevels, each with a bevel size of 0.25 mm or less would create, in coupled condition of adjacent subfloor panels, a V-shaped groove with a maximum groove width of 0.5 mm or less, which was found to be practically invisible through an installed decorative floor. The application of these (micro)bevel may prevent and/or nuance undesired small, noticeable height differences and/or ridges in between adjacent panels. In particular with thin decorative floors to be installed on top of the subfloor according to the present invention it is important that differences in height cannot be seen in the decorative floor. Thin decorative floors may for example be linoleum floors, or thin PVC floorings, or the like, preferably having a thickness of at most 10 or even 5 mm. In this respect, the edges where subfloor panels are mutually connected are the most critical since this is typically where seems or irregularities may form. Since these seems or interruptions would otherwise project through the decorative floor, which is obviously undesired, a sanding action of the subfloor would be required. The bevels or other chamfers according to the present invention have proven to be able to provide for a smooth top surface, which does not require sanding of the top surface.

Preferably, at least the bottom layer comprises one or more recesses and/or cavities and/or through-holes, such as one or more channels, grooves, slits or slots, and/or an impressed pattern. Preferably, these recesses and/or cavities and/or through-holes are arranged in a pattern. The recesses may for example be provided by means of calendaring and/or impressing and/or milling and/or drilling. Providing a recess may allow for reducing the weight of the subfloor panel. Additionally, it may contribute to the noise reduction and allows for circulation of air underneath the panel which is beneficial for certain applications. It is imaginable that the one or more recesses extend at least partially, optionally entirely, through the top layer of the subfloor panel. In particular in case of through holes the holes may extend all the way through both the bottom layer and the top layer.

According to a preferred embodiment, at least a portion of a bottom surface of the bottom layer is provided with a primer, preferably a water and/or a moisture impermeable primer. This may prevent the subfloor panel from moisture which may be present in or below the floor or structure on which the subfloor is installed. This may contribute to an increased lifespan of the subfloor panel.

Preferably, the subfloor panel, preferably a top surface and/or bottom surface of at least one subfloor panel layer, more preferably a top surface of the top layer of the subfloor panel, is provided with at least one heating layer for generating and/or dissipating heat, preferably wherein the at least one heating layer comprises at least a fraction of conductive particles, such as metal and/or graphite, for generating a resistive heating. It is imaginable that the heating layer stretches at least partially onto at least one panel side edge and/or wherein the at least one heating layer covers at least a part of at least one bevel or other chamfer and/or the square corner. It is also imaginable that the heating layer stretches at least partially onto the first and/or second coupling profile. This is in particular beneficial since this may allow for establishing an (electrical) contact between subfloor panel through the coupling profiles. Preferably, the type of heat that is generated is a resistive type of heat. Therefore it is conceivable that in particular a resistive heating coating and/or varnish, such as a graphite comprising resistive coating or varnish is applied. Preferably, the conductive particles are dispersed in a carrier of the heating layer, such that the heating layer is allowed for conducting electricity.

Preferably the resistance of the heating layer is such that a predetermined amount of heat may be generated, said predetermined amount being suitable for e.g., domestic applications and preferably safe to touch. To this end, at least one connector may be provided which connects to the heating layer and may be connected to a power source for providing an (electric) power to the heating layer. It is conceivable that resistivity values lie in between 0.05 Ohm per square meter and 50 Ohm per square meter, preferably measured at a thickness of about 50 m. Yet, resistivity values in between 100 and 1500 0hm/m2 are also conceivable depending on the application.

Optionally at least one joint sealer and/or said heating layer and/or at least one connector is provided on at least a portion of at least one edge of the subfloor panel, such that an electrical connection is established between the heating layers of adjacent subfloor panels in a coupled condition of adjacent subfloor panels. Preferably, said joint sealer comprising conductive particles. Such a joint sealer may provide for a more water resistant connection between adjacent panels. Moreover, by incorporating conductive particles in the joint sealer, said joint sealer may function as an electric connection between heating layers of adjacent panels in coupled condition. It is also conceivable that a conductive material is provided onto at least two coupling profiles. Preferably, each of the coupling profiles is coated with a conductive material. It is preferred that the conductive material covers at least a portion of at least one, preferably at least two, in particular each, coupling profile, and stretches up to, in particular upwards to, the heating layer. Preferably, at least a marginal overlap with the heating layer is established such as to form an electric contact between the conductive material and the heating layer. Preferably, the at least one connector of the subfloor panel comprises may be formed by a conductive strip, such as metal strips or another conductive connecting elements.

Preferably, at least an upper portion of the first top layer edge and/or second top layer edge is at least essentially vertical. It is also imaginable that at least an upper portion of the first top layer edge and/or second top layer edge is in contact with the upper portion of the respective first top layer edge and/or second top layer edge of an adjacent panel in coupled condition This may contribute to a more flush top surface of adjacent subfloor panels in coupled condition. Preferably, a top surface of the top layer, at least along a portion of at least one edge, is substantially flush with a top surface of a top layer of an adjacent subfloor panel in coupled condition.

The invention also relates to a floor system, comprising a plurality of coupled subfloor panels according to the invention. Preferred embodiments of the present invention are set out in the following non- limitative clauses.

1 . A subfloor panel for use beneath a decorative floor covering, in particular a floating decorative floor covering composed of a plurality of decorative floor panels, comprising:

- a top layer having a top surface and a bottom surface,

- a bottom layer having a top surface and a bottom surface,

- the top surface of the bottom layer being adhered to the bottom surface of the top layer such that the bottom layer is offset from the top layer in a direction of length and/or width, thereby leaving both the top surface of a marginal end portion of the bottom layer and the bottom surface of a marginal end portion of the top layer exposed, wherein a length and/or a width of the bottom layer is less than a length and/or a width of the top layer, creating a gap between the bottom layer of the subfloor panel and a bottom layer of an adjacent subfloor panel, and wherein the top layer comprises:

- at a first top layer edge comprising a first coupling profile, and

2. Subfloor panel according to clause 1 , wherein the top layer is composed of a single material layer.

3. Subfloor panel according to clause 1 or 2, wherein the top surface of the top layer defines the upper surface of the subfloor panel.

4. Subfloor panel according to any of the preceding clauses, wherein at least one marginal portion, preferably all marginal portions are free of any adhesive.

5. Subfloor panel according to any of the preceding clauses, wherein at least one marginal portion is provided with an adhesive. 6. Subfloor panel according to clause 5, wherein said adhesive is a pressuresensitive adhesive.

7. Subfloor panel according to clause 6, wherein the panel further comprises a removable release film initially covering the pressure-sensitive adhesive.

8. Subfloor panel according to any of the preceding clauses, wherein the top layer is, preferably directly, adhered to the bottom layer.

9. Subfloor panel according to any of the preceding clauses, wherein the top layer is adhered to the bottom layer by a thermoplastic adhesive, preferably, polyvinyl acetate.

10. Subfloor panel according to any of the preceding clauses, wherein the bottom layer is composed of a single material layer.

11 . Subfloor panel according to any of the preceding clauses, wherein at least a part of the bottom surface of the bottom layer defines the bottom surface of the subfloor panel.

12. Subfloor panel according to any of the preceding clauses, wherein at least a part of the bottom surface of the bottom layer is covered by a backing layer, such as a cork layer and/or a foamed layer.

13. Subfloor according to clause 12, wherein the backing layer is at least partially composed of at least one material chosen from the group consisting of a: preferably low density, foamed layer of ethylene-vinyl acetate (EVA), irradiation- crosslinked polyethylene (IXPE), expanded polypropylene (XPP), expanded polystyrene (XPS), a non-woven material and/or a woven material, preferably with fibres, such as made from natural fibres, like hemp or cork, and/or a recycled and/or recyclable material such as PET.

14. Subfloor panel according to any of the preceding clauses, wherein the top layer and/or the bottom layer is at least partially composed of at least one material chosen from the group consisting of: bamboo, hemp, wood, wood fibres, MDF, LDF, HDF, and plyboard.

15. Subfloor panel according to any of the preceding clauses, wherein the top layer and/or the bottom layer is at least partially composed of at least one material chosen from the group consisting of: mineral material, like magnesium oxide, gypsum, concrete, clay, talc, and/or calcium carbonate.

16. Subfloor panel according to any of the preceding clauses, wherein the top layer and/or the bottom layer is at least partially composed of at least one polymer material, preferably at least one thermoplastic material, more preferably at least one thermoplastic material is chosen from the group consisting of: PVC, PET, PP, PS, thermoplastic polyurethane (TPU), PE, in particular MDPE and/or HDPE; and combinations thereof.

17. Subfloor panel according to any of the preceding clauses, wherein the top layer and/or the bottom layer is at least partially composed a mixture of virgin and recycled polymer material.

18. Subfloor panel according to any of the preceding clauses, wherein the top layer and/or the bottom layer is at least partially composed of a water-resistant material.

19. Subfloor panel according to any of the preceding clauses, wherein the marginal end portions are substantially L-shaped.

20. Subfloor panel according to any of the preceding clauses, wherein the first coupling profile comprises:

• a first upward tongue,

• at least one first upward flank lying at a distance from the upward tongue,

• a first upward groove formed in between the first upward tongue and the first upward flank wherein the first upward groove is adapted to receive at least a part of a second downward tongue of a second coupling profile of an adjacent panel, and

• preferably at least one first locking element, more preferably provided at a distant side of the first upward tongue facing away from the upward flank, and wherein the second coupling profile comprises:

• a second downward tongue,

• at least one second downward flank lying at a distance from the downward tongue,

• a second downward groove formed in between the downward tongue and the downward flank, wherein the downward groove is adapted to receive at least a part of an upward tongue of a first coupling profile of an adjacent panel, and

• preferably at least one second locking element adapted for co-action with a first locking element of an adjacent panel, said second locking element more preferably being provided at the downward flank.

21 . Subfloor panel according to clause 20, wherein the first coupling profile and the second coupling profile are configured such that two of such panels can be coupled to each other by means of a turning movement and/or by means of a vertical movement; and/or wherein, in coupled state of adjacent panels, the first coupling profile of the panel and the second coupling profile of an adjacent panel are configured such that two of such panels can be uncoupled to each other by means of a turning movement and/or by means of a vertical movement and/or by means of a horizontal movement.

22. Subfloor panel according to any of the preceding clauses, wherein the subfloor panel comprises at least one third coupling profile and at least one fourth coupling profile located respectively at a third top layer edge and a fourth top layer panel edge, wherein the third coupling profile comprises:

• a sideward tongue extending in a direction substantially parallel to a plane defined by the subfloor panel,

• at least one third downward flank lying at a distance from and/or connecting to the sideward tongue, and

• optionally a third downward groove formed between the sideward tongue and the third downward flank, wherein the third coupling profile and the fourth coupling profile are configured such that two of such panels can be coupled to each other by means of a turning movement and/or sliding movement and/or linear movement. 23. Subfloor panel according to clause 22, wherein the fourth coupling profile comprises a fourth groove configured for accommodating at least a part of the sideward tongue of the third coupling profile of an adjacent panel, said fourth groove being defined by an upper lip and a lower lip, wherein said lower lip is optionally provided with an upward locking element, , wherein, in coupled condition: at least a part of the sideward tongue of a first panel is inserted into the fourth groove of an adjacent, second panel, and wherein at least a part of the optional upward locking element of said second panel is inserted into the optional third downward groove of said first panel.

24. Subfloor panel according to clause 23, wherein a fourth locking is provided at a distant side of the upward locking element facing away from the fourth groove, wherein said fourth locking element is configured to co-act with a locking element of a complementary coupling profile, in particular a second locking element of a second coupling profile of another panel, in coupled condition of said panels.

25. Subfloor panel according to one of clauses 22-24, wherein the first coupling profile and the fourth coupling profile are identical.

26. Panel according to any of the preceding clauses, wherein the width of the gap formed in between the lower layers of adjacent subfloor panels, in coupled condition, is substantially constant along facing edges of lower layers of said coupled subfloor panels.

27. Panel according to any of the preceding clauses, wherein the width of the gap formed in between the lower layers of adjacent subfloor panels, in coupled condition, is situated in between 1 and 10 mm, preferably 1.5 and 5 mm.

28. Subfloor panel according to any of the preceding clauses, wherein at least a part of the gap formed between the lower layers of coupled panels extends in parallel to the longitudinal direction of the panel.

29. Panel according to any of the preceding clauses, wherein at least a part of the gap formed between the lower layers of coupled panels extends perpendicularly to the longitudinal direction of the panel. 30. Subfloor according to any of the preceding clauses, wherein the length difference between the bottom layer and the top layer is situated in between 1 and 15 mm, preferably in between 1 and 10 mm, more preferably in between 1 and 6 mm.

31 . Subfloor according to any of the preceding clauses, wherein the width difference between the bottom layer and the top layer is situated in between 1 and 15 mm, preferably in between 1 and 10 mm, more preferably in between 1 and 6 mm.

32. Subfloor according to any of the preceding clauses, wherein the subfloor panel thickness in between 4 and 20 mm, more preferably between 10 and 15 mm.

33. Subfloor according to any of the preceding clauses, wherein the bottom layer and/or the top layer is/are substantially rectangularly shaped.

34. Subfloor panel according to any of the preceding clauses, wherein an upper edge region of at least two edges, preferably all edges, of the top layer is proved with a bevel or other chamfer.

35. Subfloor panel according to any of the preceding clauses, wherein the width of each bevel or other chamfer is less than 0.5 mm.

36. Panel according to any of the preceding clauses, wherein a width of at least one marginal portion is situated in between 2 cm to 20 cm, preferably in between 5 cm to 10 cm.

37. Subfloor panel according to any of the preceding clauses, wherein at least the bottom layer comprises one or more recesses, such as a channel and/or a through hole and/or an impressed pattern.

38. Subfloor panel according to clause 37, wherein the one or more recesses extend at least partially, optionally entirely, through the top layer of the subfloor panel. 39. Subfloor panel according to any of the preceding clauses, wherein at least a portion of a bottom surface of the bottom layer is provided with a primer, preferably a water and/or a moisture impermeable primer.

40. Subfloor panel according to any of the preceding clauses wherein the subfloor panel, preferably a top surface and/or bottom surface of a subfloor panel, more preferably the top surface of the top layer is provided with at least one heating layer for generating and/or dissipating heat, preferably wherein the at least one heating layer comprises at least a fraction of conductive particles, such as metal and/or graphite, for generating a resistive heating.

41 . Subfloor panel according to one of clauses 34 or 35 and clause 40, wherein the at least one heating layer covers at least a part of at least one bevel or other chamfer and/or the square corner.

42. Subfloor panel according to any of the clauses 40 - 41 , wherein at least one conductive joint sealer and/or said heating layer and/or a connecting element is provided on at least a portion of at least one edge of the subfloor panel, such that an electrical connection is established between the heating layers of adjacent subfloor panels in a coupled condition of adjacent subfloor panels.

43. Subfloor panel according to any of the preceding clauses, wherein at least an upper portion, optionally located below a bevel or chamfer if applied, of the first top layer edge and/or second top layer edge is at least essentially vertical.

44. Subfloor panel according to any of the preceding clauses, wherein at least an upper portion of the first top layer edge and/or second top layer edge is in contact with the upper portion of the respective first top layer edge and/or second top layer edge of an adjacent panel in coupled condition.

45. Subfloor panel according to any of the preceding clauses, wherein a top surface of the top layer, at least along a portion of at least one edge, is substantially flush with a top surface of a top layer of an adjacent subfloor panel in coupled condition. 46. Subfloor panel according to any of the preceding clauses, wherein the first and second coupling profiles are, at least in an engaged position, free of adhesive.

47. Subfloor panel according to the preceding clauses, wherein the subfloor panel, in particular the top surface of the top layer of the subfloor panel, is essentially free of a decorative layer and/or an embossing structure.

48. Subfloor panel according to any of the preceding clauses, wherein the ratio between the thickness of the subfloor panel and the width of at least one marginal end portion lies in between 1 :5 - 1 :75, preferably in between 1 :5 - 1 :74.

49. Subfloor panel according to any of the preceding clauses, wherein the top layer and/or the bottom layer is/are at least partially composed of at least one polymer material, preferably at least one thermoplastic material, and at least one additive chosen from the group consisting of: mineral material, like magnesium oxide, gypsum, concrete, clay, talc, chalk, wood, graphene, graphite, glass, rice, and/or calcium carbonate; embedded in said polymer material, in particular thermoplastic material.

50. Subfloor panel according to any of the preceding clauses, wherein the top layer and/or the bottom layer is/are at least partially composed of a mineral material, preferably enriched with fibers, such as fiber cement, gypsum, and/or magnesium oxide.

51 . Subfloor panel according to any of the preceding clauses, wherein the first coupling profile and the second coupling profile are configured for coupling of adjacent subfloor panels in a manner that the coupled subfloor panels are secured free of play with respect to each other.

52. Floor system, comprising a plurality of coupled subfloor panels according to any of the preceding clauses.

The invention will be elucidated on the basis of non-limitative exemplary embodiments shown in the following figures, wherein, figure 1 a and 1 b schematically show a panel according to the present invention, figure 2 is a cross-sectional view, in particular of a top layer, indicated by section A-A’ in figure 1a; figure 3 is a cross-sectional view, in particular of a top layer, indicated by section B-B’ in figure 1a; figure 4a and 4b schematically show two panels in coupled condition according to the present invention; figure 5 shows a cross-sectional view of a subfloor panel according to an embodiment of the invention; figure 6 shows a different cross-sectional view of a subfloor panel according to the invention; and figure 7 shows three subfloor panels in coupled condition.

Figure 1 a and 1 b schematically show a panel 1 according to the present invention. Figure 1 a shows the front view of a substantially rectangular panel 1 . Figure 1 b shows the rear view of a substantially rectangular panel 1. The panel 1 comprises an upper layer 2 and a lower layer 3, which may also be referred to as top layer 2 and bottom layer 3. The lower layer 3 is shifted with respect to the upper layer 2. The upper layer 2 comprises a first pair of opposite edges, in particular a first edge 4 and a complementary second edge 5, located at the long lateral sides of the panel 1 . The upper layer 2 also comprises a second pair of opposite edges, in particular a third edge 6 and a complementary fourth edge 7, located at the short lateral sides of the panel 1 in this exemplary embodiment. The upper layer 2 is exposed to the external environment. The upper layer 2 can be brought into contact with an underlayment on top of which a covering of decorative panels is applied. In another embodiment, the upper layer 2 is directly brought into contact with a covering of decorative panels. Cross-sections of lines A-A’ and B-B’ are shown in figures 3 and 4. The top surface of the bottom layer 3 being adhered to the bottom surface of the top layer 2 such that the bottom layer is offset from the top layer in a direction of length and/or width, thereby leaving both the top surface of a marginal end portion 19 of the bottom layer 3 and the bottom surface of a marginal end portion of the top layer exposed. Figure 2 is a cross-sectional view indicated by section A-A’ in figure 1a. In this non- limitative cross-sectional view merely the top layer 2 of the subfloor panel 1 is indicated. In this cross-section, the shape of the complementary first edge 104 and second 105 edge are shown in detail. The first edge 104 comprises a sideward tongue 109 which is integrally connected to the upper layer 102 of the panel 100. By means of the vertical dashed line the border between the sideward tongue 109 and the upper layer 102 is visualised. A front region 109a of the sideward tongue 109 is provided with a rounded bottom surface 110. An outer end of the rounded bottom surface 110 adjoins an inclined locking surface 111 . An opposite end of the rounded bottom surface 110 adjoins a bearing surface 112 making part of a back region 109b of the sideward tongue 109. The second edge 105 of the panel 100 comprises an upper lip 113 and a lower lip 114 defining a recess 115. Both lips 113, 114 are integrally connected to the upper layer 102 of the panel 100. By means of the vertical dashed line the border between the lips 113, 114 and the upper layer 102 is visualised. The width of the upper lip 113 is substantially smaller than the width of the lower lip 114. The recess 115 has a shape which is complementary to the shape of the sideward tongue 109. More in particular, a top surface 116 of a back region 114a of the lower lip 114 has a (complementary) rounded shape, configured to co-act with the rounded front region 109a of the sideward tongue 109, while a front region 114b of the lower lip 114 is provided with a upwardly protruding shoulder 117, configured to co-act with the bearing surface 112 of the sideward tongue 109. A lower surface 118 of the upper lip 113 is inclined and corresponds to the locking surface 111 of the sideward tongue 109. Locking at the first edge 105 and the second edge 106 of adjacent panels 100 by insertion of the sideward tongue 109 of a panel 100 to be coupled into the recess 115, wherein said panel 100 is initially held in an inclined position. After insertion of the sideward tongue 109 into the recess, the panel 100 to be coupled will be pivoted (angled) in downward direction about an axis parallel to the first edge 104 until both panels 101 are positioned in the same - commonly horizontal - plane, wherein the locking surface 111 of the sideward tongue 109 will engage the locking surface of the upper lip 118, and wherein at least a bottom front part is accommodated substantially form-fittingly in the recess 115, and wherein the bearing surface 112 is supported by the shoulder 117. Locking at the first edge 104 and the second edge 105 leads to locking of the connected panels 100 in both horizontal direction and vertical direction. The angling down locking principle of the first and second edges 104, 105 is a relatively easy locking principle which facilitates mutual coupling of panels at these edges 104, 105 tremendously.

Figure 3 is a cross-sectional view indicated by section B-B’ in figure 1a. In this non- limitative cross-sectional view merely the top layer 102 of the subfloor panel 100 is indicated. In this cross-section, the shape of the complementary third edge 106 and fourth 107 edge are shown in detail. The third edge 106 comprises an upward tongue 119, an upward flank 120 and an upward groove 121 formed between upward tongue 119 and upward flank 120. The upward tongue 119 is connected to the upper layer 102 by means of a bridge 122, which is preferably resilient to some extent. A side 119a of upward tongue 119 facing toward upward flank 120 extends in the direction of the normal N1 of the upper side 110 of the upper layer 102. The tangent R1 and the normal N1 of the upper side 110 of the upper layer 102 are thus directed toward each other (converging orientation), wherein the angle enclosed by R1 and N1 is preferably between 0 and 10 degrees in this exemplary embodiment. Due to the converging orientation of the upward flank 120 and the side 119a of the upward tongue 119 facing toward to the upward flank 120, the upward groove 122 is a closed groove, which is only accessible to a complementary counterpart by deformation of the upward tongue 119 and/or bridge 122. Another side 119b of upward tongue 119 facing toward upward flank 120 forms or may form an aligning edge enabling facilitated realization of a coupling to an adjacent floor panel 100. As shown, this side 119b functioning as aligning edge is directed away from the normal N1 of upper side 110 of the upper layer 102. An upper side 119d of upward tongue 119 does however extend in the direction of the normal N1 of the upper side 110 of the upper layer 102, and runs inclining downward in the direction of the side 119e of upward tongue 119 facing away from upward flank 120. This chamfering provides the option of giving the complementary fourth edge 107 a more robust and therefore stronger form. A part of the side 119e of the upward tongue 119 facing away from upward flank 120 is oriented substantially vertically and is moreover provided with an outward bulge 123. A lower part 120a of upward flank 120 is oriented diagonally, while an upper part 120b of upward flank 120 is shown to be substantially vertical and forms a stop surface for fourth edge 107. In between the inclined part 120a and the substantially vertical part 120b of the upward flank an additional coupling element, in particular an additional bulge 124, is provided. A lower wall part 121a of upward groove 121 is oriented substantially horizontally in this exemplary embodiment. The fourth edge 107 is substantially complementary to third edge 106. The fourth edge 107 comprises a downward tongue 125, a downward flank 126 and a downward groove 127 formed between downward tongue 125 and downward flank 126. The downward tongue 125 is connected to the upper layer 102 by means of a bridge 128, which is preferably resilient to some extent. A side 125a of downward tongue 125 facing toward downward flank 126 lies in the direction of the normal N2 of the lower side 111 of the upper layer 102. This means that a tangent R2 of side 125a of downward tongue 125 and the normal of the lower side 111 of the upper layer 102 are mutually converging, wherein the angle enclosed by R2 and N2 is preferably between 0 and 10 degrees in this exemplary embodiment. More preferably, the inclination of R1 is identical to the inclination of R2; hence, R1 and R2 are preferably parallel. Due to the converging orientation of the downward flank 126 and the side 125a of the downward tongue

125 facing toward to the downward flank 126, the downward groove 127 is a closed groove, which is only accessible for the upward tongue 119 of an adjacent panel 100 by deformation of the downward tongue 125 and/or bridge 128, as a result of which the entrance of the downward groove can be widened (temporary). A side 125b of the downward tongue 125 facing away from downward flank 126 is diagonally oriented, but has a flatter orientation than the complementary side 120a of upward flank 120, whereby a gap (air space) will be formed in the coupled position, which will generally facilitate coupling between two floor panels 100. The inclining side 125b of downward tongue 125 also functions as aligning edge for the purpose of further facilitating coupling between two panels 100. Another side 125c facing away from downward flank 126 takes a substantially vertical form, though is provided with a small cavity 129 configured to co-act with the additional bulge 124 of another panel 100. A top part of the side 125c facing away from downward flank

126 forms a complementary stop surface for stop surface 120b of upward flank 120 (of an adjacent floor panel). Downward flank 126 is oriented substantially vertically and is provided with a recess 130 adapted to receive the outward bulge 123 of the upward tongue 119 (of an adjacent panel).

Figure 4a and 4b schematically show a front view of two coupled panels 10 according to the present invention. In figure 4a the panels 10 are coupled at the long lateral sides of the panels 10. In this figure the panel edges 6, 16, 106 and 7, 17, 107 of the upper layers 12 of the panels 10 are coupled at the long lateral side of the panels 10. Between the lower layers 13 of the panels 10 a gap 18 is formed in coupled condition of the panels 10. The gap 18 extends in the same direction as the extension direction of interacting coupling profiles of the panel edges in coupled condition. So, in this embodiment the gap 18 extends in parallel to the longitudinal direction of the coupled panels 10. The width of the gap 18 is substantially equal along the extension direction of interacting coupling profiles of the panel edges in coupled condition. So, in this embodiment the width of the gap 18 is substantially equal along the longitudinal direction. Also shown in this figure is that the subfloor panels 10 adjoin in such a manner that essentially no seem is present between the top layers (or upper layers) 12 of the coupled subfloor panels 10. This provides optimum stability for a decorative panel to be laid on top of the top surface of the top layer 12. The top surface of the bottom layer 13 being adhered to the bottom surface of the top layer 12 such that the bottom layer is offset from the top layer in a direction of length and/or width, thereby leaving both the top surface of a marginal end portion 19 of the bottom layer 13 and the bottom surface of a marginal end portion of the top layer exposed. In figure 4a the marginal end portion 19 of the subfloor panel 10 indicated on the bottom is at least partially situated below the top layer 12 of the subfloor panel 10 indicated in the top. Hence, a stable support may be defined by such marginal end portions 19.

In figure 4b the panels 10 are coupled along the short lateral sides of the panels 10. In this figure the panel edges 4, 14, 104 and 5, 15, 105 of the upper layers 12 of the panels 10 are coupled at the short lateral side of the panels 10. Between the lower layers 13 of the panels 10 a gap 18 is formed in coupled condition of the panels 10. The gap 18 extends in the same direction as the extension direction of interacting coupling profiles of the panel edges in coupled condition. So, in this embodiment the gap 18 extends perpendicularly to the longitudinal direction of the coupled panels 10. The width of the gap 18 is substantially equal along the extension direction of interacting coupling profiles of the panel edges in coupled condition. So, in this embodiment the width of the gap 18 is substantially equal along the transverse direction. Also shown in this figure is that the subfloor panels 10 adjoin in such a manner that essentially no seem is present between the top layers (or upper layers) 12 of the coupled subfloor panels 10. This provides optimum stability for a decorative panel to be laid on top of the top surface of the top layer 12. In figure 4b the marginal end portion 19 of the subfloor panel 10 indicated on the top is at least partially situated below the top layer 12 of the subfloor panel 10 indicated in the bottom. Hence, a stable support may be defined by such marginal end portions 19 in this way of coupling adjacent subfloor panels 10.

Figure 5 shows a non-limitative embodiment of the subfloor panel Oaccording to the present invention. The subfloor panel 100 comprises a top layer and a bottom layer 103. Here, the top layer 102 and bottom layer 103 are schematically indicated. A portion of the bottom layer 103 extends beyond the top layer 139 thus leaving a top surface of a marginal end portion 139 of the bottom layer 103 exposed. Preferably, an upper portion 134, 135 of the first top layer edge 104 and second top layer edge 105 are essentially vertical. Hence, in coupled condition of adjacent subfloor panels 100 the essentially vertical portions 134, 135 allow to form a substantially flush top surface 140 between adjacent panels 100. It is conceivable that the top layer 102, in particular the top surface thereof, is provided with a heating layer 137. Said heating layer may be a layer of material comprising conductive particles. This may allow to form a resistive heating layer 137. Said resistive heating layer 137 may be applied in the form of a coating and/or a varnish. The first panel edge 104 and second panel edge 105 comprise complementary coupling profiles 131 , 132 allowing for interlockingly engaging with one another to establish a lock of coupled subfloor panels in the horizontal and vertical direction. Here, a first coupling profile 131 on the first panel edge 104 Is formed by a sideward tongue 131 which is configured to co-act with a second coupling profile 132 of a second panel edge 105 of an adjacent subfloor panel 100. In particular, the sideward tongue 131 of the first panel edge 104 may be received by a groove 132 of the second panel edge 105 of said adjacent subfloor panel 100.

Figure 6 shows a cross-sectional view of, preferably the same, subfloor panel 100 as shown in figure 5, wherein the cross-section displayed in figure 6 is preferably taken perpendicular to that of figure 5. Hence, this figure indicates for example the third panel edge 106 and the fourth panel edge 107. For illustrative purposes the heating layer 137 is not indicated in this figure, however may anyway be present. What is indicated are the bevels 136 or other chamfers 136 that are applied at an edge of the upper layer 102. In particular, the bevels 136 as indicated are micro bevels. The width D1 , D2 of the bevels is preferably at most 0.5 mm, more preferably at most 0.25 mm. When two subfloor panels 100 are mutually connected, adjacent bevels 136 may form a V-shape. Preferably, a maximum width is less than 0.5mm. It was observed that this size of bevel does not remain visible in a (thin) decorative flooring installed onto the subfloor. In this figure, the third coupling profile 133 and fourth coupling profile 132 are provided respectively on the third panel edge 106 and fourth panel edge 107. Here, the fourth coupling profile 132 is essentially identical to the second coupling profile 132 of the second panel edge 105. This allows the subfloor panels 100 to be connected in a more diverse manner. That is, each of the first or first and third coupling profile 131 , 133 may be coupled to any of the second or fourth coupling profile 132, which allows a short edge of a first panel to be coupled to both a short edge of an adjacent panel, or a long edge of an adjacent panel. More stability may be provided in this manner.

Figure 7 shows three interlocked subfloor panels 100 according to the invention. Here, it is also indicated that both the first coupling profile 131 and the third coupling profile 133 may be received by the either of the second or fourth coupling profile 132, which are identical. This figure also indicates that a heating layer 137 that is provided on at least two subfloor panels 100 mutually form a heating surface 138. Said heating surface 138 may be established through e.g., a conductive joint sealer which may be applied in the joint between the subfloor panels that comprise a heating layer 137. The top surface 140 formed by the interconnected subfloor panels 100 is essentially flush, or at least does not require post-laying sanding actions.

The above-described inventive concepts are illustrated by several illustrative embodiments. It is conceivable that individual inventive concepts may be applied without, in so doing, also applying other details of the described example. It is not necessary to elaborate on examples of all conceivable combinations of the abovedescribed inventive concepts, as a person skilled in the art will understand numerous inventive concepts can be (re)combined in order to arrive at a specific application.

It will be apparent that the invention is not limited to the working examples shown and described herein, but that numerous variants are possible within the scope of the attached claims that will be obvious to a person skilled in the art. The verb “comprise” and conjugations thereof used in this patent publication are understood to mean not only “comprise”, but are also understood to mean the phrases “contain”, “substantially consist of”, “formed by” and conjugations thereof.

Claims

- a top layer having a top surface and a bottom surface,

- a bottom layer having a top surface and a bottom surface,

- at a first top layer edge comprising a first coupling profile, and

- at a second top layer edge, preferably located opposite to the first top layer edge, comprising a second coupling profile being designed to engage i nterlocki ngly with said first coupling profile of the top layer of an adjacent subfloor panel in horizontal direction and vertical direction.

2. Subfloor panel according to claim 1 , wherein the top layer is composed of a single material layer.

3. Subfloor panel according to claim 1 or 2, wherein the top surface of the top layer defines the upper surface of the subfloor panel.

4. Subfloor panel according to any of the preceding claims, wherein at least one marginal portion, preferably all marginal portions are free of any adhesive.

5. Subfloor panel according to any of the preceding claims, wherein at least one marginal portion is provided with an adhesive.

6. Subfloor panel according to claim 5, wherein said adhesive is a pressuresensitive adhesive.

7. Subfloor panel according to claim 6, wherein the subfloor panel further comprises a removable release film initially covering the pressure-sensitive adhesive.

8. Subfloor panel according to any of the preceding claims, wherein the top layer is, preferably directly, adhered to the bottom layer.

9. Subfloor panel according to any of the preceding claims, wherein the top layer is adhered to the bottom layer by a thermoplastic adhesive, preferably, polyvinyl acetate.

10. Subfloor panel according to any of the preceding claims, wherein the bottom layer is composed of a single material layer.

11 . Subfloor panel according to any of the preceding claims, wherein at least a part of the bottom surface of the bottom layer defines the bottom surface of the subfloor panel.

12. Subfloor panel according to any of the preceding claims, wherein at least a part of the bottom surface of the bottom layer is covered by a backing layer, such as a cork layer and/or a foamed layer.

13. Subfloor according to claim 12, wherein the backing layer is at least partially composed of at least one material chosen from the group consisting of a: preferably low density, foamed layer of ethylene-vinyl acetate (EVA), irradiation-crosslinked polyethylene (IXPE), expanded polypropylene (XPP), expanded polystyrene (XPS), a non-woven material and/or a woven material, preferably with fibres, such as made from natural fibres, like hemp or cork, and/or a recycled and/or recyclable material such as PET.

14. Subfloor panel according to any of the preceding claims, wherein the top layer and/or the bottom layer is at least partially composed of at least one material chosen from the group consisting of: bamboo, hemp, wood, wood fibres, MDF, LDF, HDF, and plyboard.

15. Subfloor panel according to any of the preceding claims, wherein the top layer and/or the bottom layer is at least partially composed of at least one material chosen from the group consisting of: mineral material, like magnesium oxide, gypsum, concrete, clay, talc, and/or calcium carbonate.

16. Subfloor panel according to any of the preceding claims, wherein the top layer and/or the bottom layer is at least partially composed of at least one polymer material, preferably at least one thermoplastic material, more preferably at least one thermoplastic material is chosen from the group consisting of: PVC, PET, PP, PS, thermoplastic polyurethane (TPU), PE, in particular MDPE and/or HDPE; and combinations thereof.

17. Subfloor panel according to any of the preceding claims, wherein the top layer and/or the bottom layer is at least partially composed a mixture of virgin and recycled polymer material.

18. Subfloor panel according to any of the preceding claims, wherein the top layer and/or the bottom layer is at least partially composed of a water-resistant material.

19. Subfloor panel according to any of the preceding claims, wherein the marginal end portions are substantially L-shaped.

20. Subfloor panel according to any of the preceding claims, wherein the first coupling profile comprises:

• a first upward tongue,

• at least one first upward flank lying at a distance from the upward tongue,

• a second downward tongue,

21 . Subfloor panel according to claim 20, wherein the first coupling profile and the second coupling profile are configured such that two of such panels can be coupled to each other by means of a turning movement and/or by means of a vertical movement; and/or wherein, in coupled state of adjacent panels, the first coupling profile of the subfloor panel and the second coupling profile of an adjacent subfloor panel are configured such that two of such subfloor panels can be uncoupled to each other by means of a turning movement and/or by means of a vertical movement and/or by means of a horizontal movement.

22. Subfloor panel according to any of the preceding claims, wherein the subfloor panel comprises at least one third coupling profile and at least one fourth coupling profile located respectively at a third top layer edge and a fourth top layer subfloor panel edge, preferably wherein the fourth coupling profile is designed to engage interlockingly with said third coupling profile of the top layer of an adjacent subfloor panel in horizontal direction and/or vertical direction, preferably a vertical direction only, wherein the third coupling profile comprises:

• a sideward tongue extending in a direction substantially parallel to a plane defined by the subfloor panel and/or to the upper side of the core,

• preferably a third downward groove formed between the sideward tongue and the third downward flank, wherein the third coupling profile and the fourth coupling profile are configured such that two of such subfloor panels can be coupled to each other by means of a turning movement and/or sliding movement and/or linear movement.

23. Subfloor panel according to claim 22, wherein the fourth coupling profile comprises a fourth groove configured for accommodating at least a part of the sideward tongue of the third coupling profile of an adjacent subfloor panel, said fourth groove being defined by an upper lip and a lower lip, wherein said lower lip is preferably provided with an upward locking element, , wherein, in coupled condition: at least a part of the sideward tongue of a first subfloor panel is inserted into the fourth groove of an adjacent, second subfloor panel, and wherein at least a part of the optional upward locking element of said second subfloor panel is inserted into the optional third downward groove of said first subfloor panel.

24. Subfloor panel according to claim 23, wherein a fourth locking is provided at a distant side of the upward locking element facing away from the fourth groove, wherein said fourth locking element is configured to co-act with a locking element of a complementary coupling profile, in particular a second locking element of a second coupling profile of another subfloor panel, in coupled condition of said subfloor panels.

25. Subfloor panel according to one of claims 22-24, wherein the first coupling profile and the fourth coupling profile are identical and/or wherein one of the first coupling profile and/or second coupling profile is identical to one of the third coupling profile and/or fourth coupling profile.

26. Subfloor panel according to any of the preceding claims, wherein the width of the gap formed in between the lower layers of adjacent subfloor panels, in coupled condition, is substantially constant along facing edges of lower layers of said coupled subfloor panels.

27. Subfloor panel according to any of the preceding claims, wherein the width of the gap formed in between the lower layers of adjacent subfloor panels, in coupled condition, is situated in between 1 and 10 mm, preferably 1.5 and 5 mm.

28. Subfloor panel according to any of the preceding claims, wherein at least a part of the gap formed between the lower layers of coupled subfloor panels extends in parallel to the longitudinal direction of the subfloor panel.

29. Subfloor panel according to any of the preceding claims, wherein at least a part of the gap formed between the lower layers of coupled subfloor panels extends perpendicularly to the longitudinal direction of the subfloor panel.

30. Subfloor panel according to any of the preceding claims, wherein the length difference between the bottom layer and the top layer is situated in between 1 and 15 mm, preferably in between 1 and 10 mm, more preferably in between 1 and 6 mm.

31 . Subfloor panel according to any of the preceding claims, wherein the width difference between the bottom layer and the top layer is situated in between 1 and 15 mm, preferably in between 1 and 10 mm, more preferably in between 1 and 6 mm.

32. Subfloor panel according to any of the preceding claims, wherein the subfloor panel thickness in between 4 and 40 mm, preferably in between 4 and 20 mm, more preferably between 10 and 15 mm.

33. Subfloor panel according to any of the preceding claims, wherein the bottom layer and/or the top layer is/are substantially rectangularly shaped.

34. Subfloor panel according to any of the preceding claims, wherein an upper edge region of at least two edges, preferably all edges, of the top layer is proved with a bevel or other chamfer and/or a square corner.

35. Subfloor panel according to any of the preceding claims, wherein the width of each bevel or other chamfer is less than 0.5 mm, in particular less than 0.25 mm, preferably as measured in the horizontal direction from the start of said bevel or other chamfer to a top layer of an adjacent subfloor panel.

36. Subfloor panel according to any of the preceding claims, wherein a width of at least one marginal portion is situated in between 2 cm to 30 cm, preferably in between 2 cm to 20 cm, preferably in between 5 cm to 10 cm, more preferably in between 4 and 10 cm, most preferably in between 8 cm and 10 cm.

37. Subfloor panel according to any of the preceding claims, wherein at least the bottom layer comprises one or more recesses, such as a channel and/or a through hole and/or an impressed pattern.

38. Subfloor panel according to claim 37, wherein the one or more recesses extend at least partially, optionally entirely, through the top layer of the subfloor panel.

39. Subfloor panel according to any of the preceding claims, wherein at least a portion of a bottom surface of the bottom layer is provided with a primer, preferably a water and/or a moisture impermeable primer.

40. Subfloor panel according to any of the preceding claims wherein the subfloor panel, preferably a top surface and/or bottom surface of a subfloor panel layer, more preferably the top surface of the top layer is provided with at least one heating layer for generating and/or dissipating heat, preferably wherein the at least one heating layer comprises at least a fraction of conductive particles, such as metal and/or graphite, for generating a resistive heating.

41 . Subfloor panel according to one of claims 34 or 35 and claim 40, wherein the at least one heating layer covers at least a part of at least one bevel or other chamfer and/or the square corner.

42. Subfloor panel according to any of the claims 40 - 41 , wherein at least one conductive joint sealer and/or said heating layer is provided on at least a portion of at least one edge of the subfloor panel, such that an electrical connection is established between the heating layers of adjacent subfloor panels in a coupled condition of adjacent subfloor panels.

43. Subfloor panel according to any of the preceding claims, wherein at least an upper portion, optionally located below a bevel or chamfer if applied, of the first top layer edge and/or second top layer edge is at least essentially vertical.

44. Subfloor panel according to any of the preceding claims, wherein at least an upper portion of the first top layer edge and/or second top layer edge is in contact with the upper portion of the respective first top layer edge and/or second top layer edge of an adjacent panel in coupled condition.

45. Subfloor panel according to any of the preceding claims, wherein a top surface of the top layer, at least along a portion of at least one edge, is substantially flush with a top surface of a top layer of an adjacent subfloor panel in coupled condition.

46. Subfloor panel according to any of the preceding claims, wherein the first and second coupling profiles are, at least in an engaged position, free of adhesive.

47. Subfloor panel according to the preceding claims, wherein the subfloor panel, in particular the top surface of the top layer of the subfloor panel, is essentially free of a decorative layer and/or an embossing structure.

48. Subfloor panel according to any of the preceding claims, wherein the ratio between the thickness of the subfloor panel and the width of at least one marginal end portion lies in between 1 :5 - 1 :75, preferably in between 1 :5 - 1 :40.

49. Subfloor panel according to any of the preceding claims, wherein the top layer and/or the bottom layer is/are at least partially composed of at least one polymer material, preferably at least one thermoplastic material, and at least one additive chosen from the group consisting of: mineral material, like magnesium oxide, gypsum, concrete, clay, talc, chalk, wood, graphene, graphite, glass, rice, and/or calcium carbonate; embedded in said polymer material, in particular thermoplastic material.

50. Subfloor panel according to any of the preceding claims, wherein the top layer and/or the bottom layer is/are at least partially composed of a mineral material, preferably enriched with fibers, such as fiber cement, gypsum, and/or magnesium oxide.

51 . Subfloor panel according to any of the preceding claims, wherein the first coupling profile and the second coupling profile are configured for coupling of adjacent subfloor panels in a manner that the coupled subfloor panels are secured free of play with respect to each other.

52. Floor system, comprising a plurality of coupled subfloor panels according to any of the preceding claims.