EP3423646B1

EP3423646B1 - Base floor of a building and a method for construction of a base of a building

Info

Publication number: EP3423646B1
Application number: EP17759326.6A
Authority: EP
Inventors: Ari Ervasti
Original assignee: Pohjolan Tilaelementti Oy
Current assignee: Pohjolan Tilaelementti Oy
Priority date: 2016-03-02
Filing date: 2017-03-02
Publication date: 2020-11-25
Anticipated expiration: 2037-03-02
Also published as: FI20165168A; EP3423646A4; WO2017149203A1; EP3423646A1

Description

This invention relates to a base floor of a building and to a method for constructing a base floor of a building.
In the base floors of residential buildings a so-called ground-supported slab of concrete, which is cast onto a thermal insulation layer installed onto a levelled gravel bed, is commonly used. Ground slabs do not have underside ventilation so they can only dry from their upper surface. Because of tight construction schedules, ground-supported slabs are often coated before they have dried out sufficiently, which causes mould and indoor air problems and expensive repairs of floor coverings.
Base floors of buildings can also be fabricated as so-called ventilating floor bases, for example, of hollow-core slabs or on bearing timber joists. Construction costs of base floors fabricated of hollow-core slabs are high, and waiting for the structural moisture to be exhausted also extends the construction time. Further, the alkalinity of concrete is neutralized after a drying-out period of approximately 10 years so that it will become a good breeding ground for fungi and microbes. A problem with timber-framed ventilating base floors is that outdoor air is condensed into the timber structures, especially in summer. Moisture-containing timber offers a favourable breeding ground for microbes and moulds.
It is an object of the invention to introduce a base floor of a building and a method for construction of a base floor of a building, with which problems related to prior art can be minimized.
The objects of the invention are achieved with a base floor of a building and a method for the construction of the base floor of a building, which are characterized in what is disclosed in the independent patent claims. Some advantageous embodiments of the invention are disclosed in the dependent patent claims.
Examples of prior art can be found in documents FR2765906A1 , US2015004371 A1 , US6421969B1 , WO0238370A2 , WO9217664A1 and XP055413779.
In accordance with the present invention, there is provided a base floor of a building having the features of claim 1.
Air can thus flow along flow paths between the first and second surface and exit from between the surfaces through apertures opening to the end edges and/or side edges of the base floor. Such a base floor has a ventilating structural part between the bearing base and the building to be built onto the base floor. Thus, the ease of fabricating a ground-supported base floor and the moisture-technical functionality of a ventilating base floor is combined in the base floor.
In an advantageous embodiment of the base floor of a building of the invention said thin sheet structure comprises corrugated metal sheets, the longitudinal direction of the folds of the corrugated sheets being substantially parallel to the direction of the first and/or second surface of the slab element. In this connection, corrugated metal sheets refer to shaped thin steel sheets commonly used in construction engineering, the wall thickness of the thin steel sheets being approximately in the range of 0.8-2.0 mm. These thin steel sheets typically have a regular cross-section, which comprises grooves i.e. folds in the longitudinal direction of the corrugated sheet. At the bottom of and between the grooves there are flat sheet sections, which define the level of the upper surface and level of the lower surface of the corrugated sheets. Corrugated sheets are used in buildings typically supported from their ends, as so-called sheets bearing to one direction or as mould pieces of composite steel-concrete slabs.
A thin sheet structure mentioned in a second advantageous embodiment of the base floor of a building comprises a first layer of first corrugated sheets, in which the folds have a first longitudinal direction, and a second layer of second corrugated sheets, in which the folds have a second longitudinal direction, the second longitudinal direction being at an angle α in relation to the first longitudinal direction, and the first and second corrugated sheets are attached to each other from their superimposed surfaces. Air flow paths parallel to the folds are then formed by the folds between the corrugated sheets. Preferably, the angle α between the longitudinal direction of the folds of the first corrugated sheets and the longitudinal direction of the folds of the second corrugated sheets is a substantially right angle. In this case, air flow paths at a right angle in relation to each other are formed into the corrugated sheet. The surfaces of the superimposed corrugated sheets positioned against each other are flat sections between the folds and at the bottom of the corrugated sheets. The corrugated sheets can be attached to each other at these points, for example, by screws or rivets drilled through the corrugated sheets.
In a third advantageous embodiment of the base floor of a building of the invention, there is a beam-type edge support withstanding flexural stress in the end edges and/or side edges. The edge support divides a point load targeted at the edge of the slab element for a longer length of the edge of the slab element. Said edge support is preferably a C- or I- profile of metal.
In yet another advantageous embodiment of the base floor of a building of the invention, there is thermal insulation material between the first and second surface. Alternatively, or additionally, there may be heating, plumbing, air conditioning or electrical installation components, such as water pipes, sewer pipes, air-discharge pipes or tubing for electric wires between the first and second surface.
In yet another advantageous embodiment of the base floor of a building of the invention there is a non-woven fabric and a layer of hardened sealing compound between the first corrugated sheets and second corrugated sheets. The sealing compound can be, for example, pumped floor filler.
In accordance with the present invention, there is provided a method for constructing a base floor of a building having the features of claim 10.
In an advantageous embodiment of the method of the invention, a first layer is formed of the first corrugated sheets, the folds having a first longitudinal direction, and a second layer is formed of the second corrugated sheets onto the first layer, the folds having a second longitudinal direction, the second longitudinal direction being at the angle α in relation to the first longitudinal direction, and the first and second corrugated sheets are attached to each other from the superimposed surfaces.
In a second advantageous embodiment of the method of the invention, a stretched non-woven fabric is placed onto the first layer before forming the second layer. Hardening sealing compound is preferably cast above the non-woven fabric. The sealing compound can be pumped on the non-woven fabric via a pipe through the open ends of the folds of the corrugated sheets or by preparing holes to the upper corrugated sheet for pumping the sealing compound. The hardened sealing compound forms a stiffening and lattice-type structure supporting the base floor between the corrugated sheets. The weight of the sealing compound makes the non-woven fabric to bend down towards the bottom of the corrugated sheet, but nevertheless remaining distinctly within a distance from the surface of the fold of the lower corrugated sheet. This makes it possible for water to exit from the sealing compound also through the non-woven fabric, which speeds up the drying of the sealing compound.
It is an advantage of the base floor of a building of the invention that it is moisture-technically more secure and cheaper to construct, compared with known solutions.
In addition, it is an advantage of the invention that it is mould-proof, unlike known timber-framed ventilating base floors.
The invention is next described in detail, referring to the attached drawings, in which

Figure 1a illustrates in an exemplary manner a slab element used in the construction of a base floor of the invention, seen obliquely from above;
Figure 1b illustrates in an exemplary manner an advantageous embodiment of a slab element used in the construction of a base floor of the invention as a cross-sectional view; and
Figure 2 illustrates in an exemplary manner a cross-sectional view of a base floor of the invention.

In Figure 1a there is illustrated in an exemplary manner a slab element 10 used in the construction of a base floor of the invention, seen obliquely from above. The slab element comprises a first corrugated sheet 12a and a second corrugated sheet 12b placed on top of the first corrugated sheet. The corrugated sheets are shaped zinc-coated construction parts made of thin steel sheets and generally used in construction engineering, the wall thickness of the sheets being 0.8-2.0 mm. The corrugated sheets have a so-called trapezoidal cross-section, i.e. they have folds in the longitudinal direction of the corrugated sheet, which have walls in an oblique position and substantially straight sections at the bottom of the folds and in the spaces between them so that the substantially straight sections define the plane of the upper and lower surface of the corrugated sheet. Superimposed corrugated sheets contact each other by the straight sections between the folds. The first and second corrugated sheets are superimposed so that the longitudinal directions of their folds are substantially at a right angle to each other. The superimposed corrugated sheets are attached to each other from their contacting superimposed sections by rivet nuts 14, which are screwed in place into the holes drilled for them. The slab element illustrated in Figure 1a has only one first corrugated sheet 12a and one second corrugated sheet 12b. It is obvious that the slab element can have several first and second corrugated sheets, which are placed side by side so that they overlap from their edges.
In the slab element 10 illustrated in Figure 1a, the plane of the lower surface of the first corrugated sheet 12a forms the first surface 16a of the slab element, and the plane of the upper surface of the second corrugated sheet 12b forms the second surface 16b of the corrugated sheet. The slab element is a rectangle so that it has two end edges, the first end edge 18a and the second end edge 18b, and two side edges, the first side edge 20a and the second side edge 20b. Thus, channels functioning as air flow paths are formed at the places of the folds between the first and second surface, which extend from the first end edge to the second end edge and from the first side edge to the second side edge. The channels are open through their entire length so that air can flow freely along them.
The first end edge 18a has a C-profile formed of a thin steel sheet, the first flange of which is positioned against the upper surface of the first corrugated sheet 12a and the second flange sets against the bottom of the fold at the edge of the second corrugated sheet 12b. The C-profile forms a beam-type edge support 22 withstanding bending stress, which distributes the point loads perpendicular to the surface of the slab, targeted at the first end edge of the slab element to a longer way along the edge of the first corrugated sheet. The edge support can be located in all or only in some edges of the slab element.
In Figure 1a, the edge of the second corrugated sheet 12b does not extend quite to the second end edge 18b of the slab element. This makes it possible to attach two slab elements with each other from their edges by making the end strips of the first corrugated sheets 12a to overlap and by attaching the overlapping sections with each other using rivet nuts. Naturally, the second end edge of the slab element can have an edge support 22 in the same way as in the first edge, if there is no need to connect the slab elements. The slab element can be provided with crane hooks or lift holes facilitating their moving.
In Figure 1b there is illustrated in an exemplary manner an advantageous embodiment of the slab element used in the construction of a base floor of a building of the invention as a cross-sectional view. This embodiment contains all the same structural parts as the slab element shown in Figure 1a. In this embodiment, there is further a non-woven fabric 35 between the first corrugated sheets 12a and the second corrugated sheets 12b. The non-woven fabric is spread in place onto the first corrugated sheets so that the non-woven fabric covers the entire area limited by the first corrugated sheets. The non-woven fabric is stretched straight, after which the second corrugated sheets are attached to the first corrugated sheets from their superimposing surfaces so that the non-woven fabric stretched straight remains compressed between the first and second corrugated sheets.
After this, self-spreading hardening sealing compound 37 is pumped between the second corrugated sheet and the non-woven fabric. On the non-woven fabric, the sealing compound spreads to the entire length of the fold in the longitudinal direction of the folds of the second corrugated sheets. At the place of the folds of the first corrugated sheets the non-woven fabric is pressed downwards by the weight of the sealing compound but remains nevertheless clearly away from the surface of the upwards opening folds of the first corrugated sheets. Thus, the sealing compound forms a square-type plane between the corrugated sheets when spreading onto the non-woven fabric, which stiffens the slab element upon hardening. The thickness of the sealing compound layer can be chosen according to properties which are desired of the slab element. The thickness of the sealing compound layer can be, for example, 40-60 mm, preferably 50 mm.
The sealing compound can be dispensed onto the non-woven fabric, for example, through the open ends of the folds of the second corrugated sheets. A second option is to make holes to the second corrugated sheets, through which sealing compound can be led to the cavities defined by the second corrugated sheets and the non-woven fabric. It is easiest to dispense the sealing compound with a pump and casting pipe. The sealing compound can be, for example, pumped floor filler. The non-woven fabric can be, for example, a filter cloth made of polypropylene, so-called cast protection cloth, which is used for separating the floor filler layer from the base.
In Figure 2 there is illustrated in an exemplary manner a cross-sectional view of a base floor of a building of the invention. The base floor forms part of the thermally insulated outer shell of the building. The base floor is built using the method of the invention by first forming a compacted soil layer 50 with a levelled upper surface, preferably a gravel or crushed gravel layer to the construction site. After this, thermal insulation sheets 24 are loaded onto the surface of the soil layer so that a uniform thermal insulation layer with a flat upper surface, acting as frost insulation is formed onto the surface of the soil layer. The proper thickness of the thermal insulation layer depends on the thermal insulation demands posed on the floor and on the thermal insulation ability of the thermal insulation material. The thermal insulation sheets are made of thermal insulation material withstanding long-term compression stress and moisture. The thermal insulation sheets must withstand loads and stresses caused by the use of the building without significant contraction and without substantial deterioration of the thermal insulation characteristics. One possible thermal insulation sheet applicable to the base floor is an extruded polystyrene sheet, the short-term compression strength of which is over 700 kPa and the long-term compression strength over 315 kPa.
A slab 30 bearing vertical loads is fabricated onto the upper surface of the thermal insulation layer of slab elements of the invention illustrated in Figure 1. Individual slab elements are attached to each other from their edges so that a uniform slab of the size of the entire base floor of the building is generated, as is shown in Figure 2. The slab 30 formed in this way functions as the slab substructure of the building to be built on it. The outer walls 40 of the building are fabricated onto the end and side edges of the slab. Part of the edges of the slab are braced with edge supports 22. The slab consisting of slab elements thus functions as a bearing structure, which distributes the loads originating from the building onto the surface of the bearing thermal insulation layer. The edges of the slab are clad with thermal insulation sheets 24 coated with stone material. The thermal insulation sheets can have ventilation holes 42 opening between the first surface 16a and second surface 16b for air flow-through.
Channels formed at the folds of the slab elements function as air flow paths, along which air can flow between the upper and lower surface of the slab. Moisture possibly rising from the ground to the folds of the slab element thus transfers along with the air flow outside the slab, and it is not able to flow through the corrugated metal sheet to the structures or room space of the building. The corrugated sheets and the thermal insulation layer are both made of moisture-resistant material, which does not function as a breeding ground for microbes or mould. Thus, the base floor of the building is moisture-technically functioning. The base floor ventilation can be intensified, when needed, by means of an exhaust fan or by providing the base floor with a natural ventilation by directing an exhaust air pipe from the base floor to the roof of the building.
A thermal insulation sheet 24 with good compression strength, a shell panel of reinforced concrete or a construction sheet can be installed onto the upper surface of the slab 30, onto which floor heating and floor coating, such as plastic wall-to-wall carpet, parquet floor 26 or ceramic tile can be installed. Floatable and expanding, self-hardening thermal insulation material, such as extrudable polystyrene, which insulates heat and improves the mechanical and acoustic characteristics of the slab element can be installed inside the slab element. Further, heating, plumbing, air-conditioning and electrical components, such as water and sewer pipes, air-discharge channels and tubing for electric wiring can be installed inside the slab element, between the first and second surface.
In addition to the base floors of buildings, the slab element of the invention can also be used in other constructions, in which good mechanical resistance, thermal insulation or transferability of the structures are required. Such constructions are e.g. different base structures of waste disposal sites and artificial ice rinks.
In the specification above the base floor of a building is constructed of slab elements comprising first and second corrugated sheets. The base floor of a building of the invention can also be built on site by first forming a first layer of the first corrugated sheets onto the bearing base and a second layer of the second corrugated sheets onto this layer. After forming the corrugated sheet layers, the first and second corrugated sheets are attached to each other from their superimposed sections by rivet nuts, self-tapping screws or other suitable fastening elements. A non-woven fabric can be installed between the corrugated sheets, and sealing compound can be cast onto the non-woven fabric after the second corrugated sheet has been fastened in place. When building in situ, the thin sheet structure can be built directly as a slab structure the size of the base floor. An advantage of building in situ is that the corrugated sheet can be transported to the construction site in a tight bundle taking only little space, which lowers the transport costs.
Some advantageous embodiments of the base floor of a building and a construction method of the base floor of the building have been described above. The invention is not limited to the solutions specified above, but the inventional idea can be applied in different ways within limits set by the patent claims.

Claims

Base floor of a building functioning as a substructure of a building, the base floor comprising a compacted and levelled soil layer (50), a hard thermal insulation layer (24) and a load bearing slab (30), wherein the hard thermal insulation layer (24) is formed on the surface of the compacted and levelled soil layer (50) and wherein the load bearing slab (30) is formed on the hard thermal insulation layer (24), wherein outer walls (40) of the building are to be fabricated onto end edges (18a, 18b) and side edges (20a,20b) of the load bearing slab (30), wherein the said slab (30) comprises a thin sheet structure withstanding compression stress and comprising air flow paths parallel to its lower and upper surfaces, wherein the lower surface of the thin sheet structure forms a first surface (16a) positioned against the hard thermal insulation layer (24) and wherein the upper surface of the thin sheet structure forms a second surface (16b) positioned at a distance from the first surface (16a).
Base floor of a building according to claim 1, characterized in that said thin sheet structure comprises corrugated metal sheets (12a, 12b), the longitudinal direction of folds of the corrugated sheets (12a, 12b) being substantially parallel with the first and/or second surface (16a, 16b) of the slab element (10).
Base floor of a building according to claim 1 or 2, characterized in that said thin sheet structure comprises a first layer of first corrugated sheets (12a), in which the folds have a first longitudinal direction, and a second layer of second corrugated sheets (12b), in which the folds have a second longitudinal direction, which second longitudinal direction is at an angle α in relation to the first longitudinal direction, and the first and second corrugated sheets (12a, 12b) are attached to each other from their superimposed surfaces.
Base floor of a building according to claim 3, characterized in that the angle α between the longitudinal direction of the folds of the first corrugated sheets (12a) and the folds of the second corrugated sheets (12b) is a substantially right angle.
Base floor of a building according to any of the claims 1-4, characterized in that the end edges (18a, 18b) and/or side edges (20a, 20b) have a beam-type edge support (22) resistant to bending stress.
Base floor of a building according to claim 5, characterized in that said edge support (22) is a C- or I-profile of metal.
Base floor of a building according to any of the claims 1-6, characterized in that there is thermal insulation material between the first surface (16a) and the second surface (16 b).
Base floor of a building according to any of the claims 1-7, characterized in that there are heating, plumbing, air conditioning and electrical installation components, such as water or sewer pipes, air discharge pipes or tubing of electric wires between the first surface (16a) and second surface (16b).
Base floor of a building according to any of the claims 1-8, characterized in that there is a non-woven fabric (35) and a layer of hardened sealing compound (37) between the first corrugated sheets (12a) and second corrugated sheets (12b).
Method for constructing a base floor of a building functioning as a substructure of a building, in which method a hard thermal insulation layer (24) is formed on the surface of a compacted and levelled soil layer (50), a load bearing slab (30) is formed on the hard thermal insulation layer (24), and wherein outer walls (40) of the building are to be fabricated onto end edges (18a, 18b) and side edges (20a,20b) of the load bearing slab (30), wherein the said slab (30) comprises a thin sheet structure withstanding compression stress and comprising air flow paths parallel to its lower and upper surfaces, wherein the lower surface of the thin sheet structure forms a first surface (16a) positioned against the hard thermal insulation layer (24) and wherein the upper surface of the thin sheet structure forms a second surface (16b) positioned at a distance from the first surface (16a).
Method according to claim 10, characterized in that in the method a first layer is formed of the first corrugated sheets (12a), the folds of which have a first longitudinal direction, and a second layer is formed onto the first layer of second corrugated sheets (12b), the folds of which have a second longitudinal direction, the second longitudinal direction being at an angle α in relation to the first longitudinal direction, and the first and second corrugated sheets are attached to each other from their superimposed surfaces.
Method according to claim 11, characterized in that a stretched non-woven fabric (35) is installed onto the first layer before the formation of the second layer.
Method according to claim 12, characterized in that a hardening sealing compound (37) is cast above the non-woven fabric.