EP3978703B1

EP3978703B1 - A vapour controlling insulation structure for a flat or low slope warm roof and method for installing the same

Info

Publication number: EP3978703B1
Application number: EP21199733.3A
Authority: EP
Inventors: Mona Ammitzbøll RASMUSSEN
Original assignee: Saint Gobain Denmark AS
Current assignee: Saint Gobain Denmark AS
Priority date: 2020-09-30
Filing date: 2021-09-29
Publication date: 2023-09-20
Anticipated expiration: 2041-09-29
Also published as: EP3978703A1; DK181178B1; DK3978703T3; FI3978703T3; DK202070666A1

Description

Technical Field

The present invention relates to a vapour controlling insulation structure for a flat or low slope warm roof according to the preamble of claim 1. The invention furthermore relates to a method of laying a vapour controlling insulation structure for a flat or low slope warm roof on a load supporting structure.

Background Art

When the roof structure of a flat roof or a low slope roof, i.e. a warm roof where the insulation is positioned above the structural load supporting roof layer, is to be constructed, usually the insulation structure is provided directly on the load supporting layer. The load supporting layer can be of concrete, wood, lightweight concrete or profiled steel plates. On top of the insulation surface a roof covering means such as roofing membrane is positioned, forming the exterior of the roof. Roofing membranes are most commonly made modified bitumen or from synthetic rubber, thermoplastic (PVC or similar material).
The slope of the roof is mainly between 5° and 20°. Often the inclination is just around 5°.
The problem with the current insulation structures of low slope roofs is when you have an inclined roof supporting layer, the insulation layers must accomplish several purposes in order for fulfil the needs in every step of the life-cycle of the insulation. In the production phase the insulation has to be produced efficiently on a production line, has to be handled efficiently on a stock and must be easy to transport to the installation site.
At the installation site the insulation must be stored until use, and be easy to install by unexperienced labour, who also has to be able to walk on the different insulation layers in order to have an efficient and safe working environment.
In the final insulation structure the temperature and humidity difference between outside and inside of the building with the roof structure gives a need to control that the vapour stays on the warm inner side of the structure. This is usually done with a vapour barrier i.e. a vapour controlling membrane such as a bitumen layer, a plastic layer or a vapour controlling membrane of another material known in the art to be used for the purpose. In the majority of buildings in regions with colder climate most of the year, the vapour controlling membrane must be placed with a third or less of the insulation placed on the inner side of the membrane, in order to secure the humidity does not turn into water droplets with severe damage to the structure and mould growth as an unfortunate outcome. The vapour barrier also constitutes the airtightness of the insulated roof structure if made correctly preventing heat loss through convection.
If the load supporting layer of the low slope roof is constituted by profiled steel plates, the insulation layers should preferably be stable enough to walk on when mounting the vapour controlling membrane and subsequently when mounting the roofing membrane, also when the insulation boards of the insulation layer are not fully supported i.e. only supported by the profile top parts.
A solution can be seen in WO 02/099220 where the vapour barrier is simply placed above the steel profiles causing the mounting of the vapour barrier to be risky for the roofers when they afterwards have to walk on the often opaque vapour barrier covering the profiles - and also it is hard to get a fully watertight vapour barrier as the proper taping or welding of joints between one or more lengths of vapour barrier can be challenging to perform on the bumpy profiled steel plates.
If a fire occurs beneath such a structure with load supporting layer of profiled steel plates the vapour controlling membrane will burn and add to the severity of the fire if placed right above the steel profile as the steel plate transports the heat from the fire instantly. In order to prevent this scenario, some countries wisely demand a minimum of 50 mm insulation between the profiled steel and the vapour barrier.
Further in WO 02/099220 Fig. 1 it is shown how an additional layer of load dispersing material of glass veil is added to the insulation board facing down towards the profiled steel plates. This is a further challenge for the unexperienced roofer to place the insulation board correctly, and it is increasing the cost of the insulation board.
As can be seen in EP 2860132 it is common to provide a roof insulation structure consisting of two or more different types of insulation which differ in respect of material properties, for example their compression strength, point load, and fibre direction. The density can then be increased or reduced in the part of the construction where this serves a purpose. This is done in order to reduce solely the cost of the product. This however increases the complexity of the production and installation of the needed insulation material for the roof. As the costs of materials, labour, stock, transport and waste removal is changing in relation to each other along with the increased focus on reducing excess material in an environmental aspect, there is still room for improvement as regards to the cost and material efficiency in the manufacture and mounting relative to the prior art low slope insulation structures.
WO2020164900A1 discloses a thermal and/or acoustic insulation system as waterproofing for a flat or flat inclined outside surface of a building, especially for a flat roof or a flat inclined roof, consisting of at least one insulation element made of mineral wool, and having a major surface, and a lining element consisting of at least a first layer made of lining material and a second layer made of a glue activatable by heat and oriented to the major surface of the insulation element.
US 4 719 723 A , EP 2 316 641 A1 and WO 2011/144819 A1 disclose further known vapour controlling insulation structures. J

Summary of Invention

Accordingly, the invention provides a vapour controlling insulation structure for a flat or low slope warm roof with a load supporting structure, comprising a first insulation layer, a vapour controlling membrane, and a second insulation layer, said vapour controlling membrane situated between the first insulation layer and second insulation layer, where said second insulation layer exhibits a top surface with an area (A) adapted for mounting of a roofing membrane, where the first insulation layer exhibits an intermediate surface, said intermediate surface adapted for mounting of said vapour controlling membrane, and where the first insulation layer is with a thickness (t) and constituted by one or more insulation boards, characterized in that said second insulation layer is constituted by two stacked sub-layers both with substantially the same thickness (t) as the first insulation layer.
The insulation boards may be box-shaped, i.e. with six rectangular faces, as it is per se known in the art. Further the insulation boards may, as it is per se known in the art, have a quality that allows for walking upon the boards e.g. during installation of a vapour controlling insulation structure.
By having three layers with the same thickness (t), it is a simple and easy way to secure that the vapour controlling membrane will be installed with a third of the total thickness of the insulation placed nearest to the inner and lower side of the low slope warm roof. This will prevent the humid air at the warm inner side of the building from turning into water droplets inside the insulated structure thus preventing severe damage to the structure and hindering mould growth that could harm the occupants of the building.
For creating a larger area of the first insulation layer, two or more insulation boards are placed side-by-side their thickness being perpendicular to the intermediate surface. When the quality of the insulation boards so allows, this constitutes at the same time a good stable basis that is able to be walked securely upon by the roofers, while mounting the vapour membrane, and make the sealing between two or more rows of rolled out membrane foil very airtight in a safe and easy manner. The sealing can be done by welding or taping or any other preferred method stated by the producer of the vapour controlling membrane, which then also will serve as an airtightness of the roof structure.
In an embodiment the two stacked sub-layers are each constituted by one or more insulation boards of the same material and with the same material dimensions and material properties as the insulation boards constituting the first layer.
By using the same insulation board products i.e. products made of the same material, with the same dimensions and properties in all of the insulation boards for the insulation structure, it is much easier to produce, intermediately store and subsequently transport to the job-site. The cost and environmental impact of the insulation boards needed for the structure is thereby reduced to a minimum. Also on the job-site it is much easier to store and handle for an unexperienced workforce. When lifting the products to the roof supporting layer no effort has to be put into placing the products correctly as all of the insulation boards will fit anywhere in the construction of the insulation structure.
In a further embodiment the insulation boards are box-shaped and are symmetric relative to a centre point in respect of material properties and dimensions.
Hereby further, the building process of the structure is very simple to explain to unexperienced workers or roofers and will be very easy to install correctly without the risk of mounting the products upside down because due to the symmetry relative to a centre point, so-called point symmetry, the properties of the insulation boards are not changed by turning the insulation boards upside down. For creating a larger area of a sub layer, two or more insulation boards are placed side-by-side their thickness being perpendicular to the top surface.
In an embodiment the first insulation layer exhibits an intermediate surface and both of the sublayers of the second insulation layer exhibits an intermediate sublayer surface each with an area equal to the area (A) of the top surface.
By having three layers each constituting a surface with the same area, and all three layers being the same insulation board product, the excess material from the job-site is significantly reduced as this will amount to less than one single pallet of the product. It is common to have two, three or more different materials pallets left when the insulation structure is finished which will amount to several cubic metres of excess material which unfortunately often goes to landfill or requires a costly upcycling process.
In an embodiment the insulation board is made of mineral wool, preferably glass wool.
When using mineral wool as insulation board material the insulation structure will be non-combustible. When further using glass wool as insulation board material the weight of the insulation boards is significantly reduced while keeping a very good strength and dimensional stability of the insulation boards.
In an embodiment the load supporting structure is constituted by profiled steel plates.
When the load supporting structure is constituted by profiled steel plates it is a preferred combination to be using mineral wool in the first insulation layer and also the upper sublayer in order to secure the fire safety for the roofer and also for the final structure in the warm roof of the building.
In an embodiment the compressive strength of said insulation board in a direction perpendicular to the top surface is above 20 kPa, preferably between 25-80 kPa.
A certain minimum of compression strength is required in order to carry the weight of the roofer when mounting the insulation structure and membranes, and also for long term dimensional stability of the structure when the roof is accessed by maintenance personnel throughout the lifetime of the building.
In an embodiment two or more insulation boards are adapted to be positioned directly on the load supporting structure, wherein the two or more insulation boards are placed side-by-side constituting the first insulation layer exhibiting an intermediate surface with an area (A) adapted for mounting of a vapour controlling membrane, where a further number of insulation boards are placed side-by-side constituting a sublayer as the lower part of the second insulation layer constituting an intermediate sublayer surface adapted for positioning a further number of insulation boards placed side-by-side, constituting another sublayer being the upper half of the second insulation layer, and constituting a top surface with an area (A) adapted for mounting of a roofing membrane.
In an embodiment the R-value of said one or more insulation boards is one third of the required R-value of the insulation layers in the vapour controlling insulation structure.
When the insulation board is optimized to serve the purpose of creating a certain R-value, no excess material is used to fulfil the need of the building owner. This gives and optimized environmental footprint. R-Value in this regard meaning the 'resistance to heat flow' of the construction as a whole, to which the insulation product is the most significant contributor.
In an embodiment the R-value of the vapour controlling insulation structure is 1/0,15 m²K/W.
Many production and storage facilities has a demand for an R-value, which is the thermal resistance, of 1/0,15 m²K/W so that these buildings do not get overheated in the warm periods, which could lead to a demand for energy consuming cooling. So an optimized structure described in these claims for these buildings will contribute significantly to a better environmental footprint.
Further, the invention provides a method of laying a vapour controlling insulation structure on a load supporting structure, comprising the consecutive steps of positioning one or more insulation boards with a thickness (t) on a load supporting structure, such as a profiled steel structure for a warm roof, whereby an intermediate surface is constituted; positioning a vapour control membrane on the intermediate surface; positioning one or more of the insulation boards with the thickness (t) whereby an intermediate sublayer surface is constituted; and positioning one or more of the insulation boards with the thickness (t) whereby a top surface with an area (A) is constituted and adapted for mounting of a roofing membrane. When using this method only two products are needed to create a solid vapour controlling insulation structure, namely the insulation boards and the vapour controlling membrane. The system is easy to mount for unexperienced roofers and requires only a low level of instruction to have a good durable roof as outcome. The intermediate surface and/or the intermediate sublayer surface can preferably be with the same area (A) as the top surface.
In an embodiment the insulation boards for the two sublayers are of taken from the same pallet and placed in the second insulation layer.
When both of the two sublayers above the vapour barrier are constructed with insulation boards from the same pallet there is less transporting of pallets and insulation boards on the roof during the construction of the two sub-layers. This saves time and work effort for the roofers. If the thickness required for obtaining 1/3 of the R-value times two, is below the grip size of a roofer's hand, the roofer can take two stacked insulation boards from the pallet at a time and place these pre-stacked boards directly on to the supported vapour controlling membrane.

Brief Description of Drawings

In the following, the invention will be described in further detail with reference to the drawings in which:
Fig. 1 is a schematic drawing of an embodiment of the invention

Description of Embodiments

Referring to Fig. 1 a vapour controlling insulation structure 1 is placed on a load supporting structure 2. In this embodiment the load supporting structure 2 is a profiled steel plate structure, where only the top part of the profiled steel plates will be supporting the vapour controlling insulation structure 1.
An insulation board 8 is as a first insulation board positioned directly on the load supporting profiled steel plate structure 2 constituting a first insulation layer 3, and thereby exhibiting an intermediate surface 7 with an area A adapted for mounting of a vapour controlling membrane 4. Further two insulation boards 8, which can be taken from the same pallet as the first insulation board 8, are placed stacked upon the vapour membrane 4 constituting the second insulation layer 5. The second insulation layer 5 is thereby comprised of one insulation board 8 constituting a sublayer 9 being the lower half of the second insulation layer 5 and with an intermediate sublayer surface 10 with the area A adapted for positioning a further insulation board 8 constituting another sublayer 9 being the upper half of the second insulation layer 5, and constituting a top surface 6 with the area A adapted for mounting of a roofing membrane. The three insulation boards 8 all have the same thickness t and are made from the same material. Further the three insulation boards 8 are in the present embodiment point symmetrical in regard of quality and dimensions whereby they may be turned upside down without thereby changing the properties of the vapour controlling insulation structure 1.
The insulation boards 8 are in the present embodiment made of mineral wool, especially glass wool, have a compressive strength in a direction perpendicular to the top surface 6 is above 20 kPa, preferably between 25-80 kPa, and the R-value of the insulation boards 8 is one third of the required R-value of the insulation layers in the vapour controlling insulation structure. Thus in the present embodiment the R-value of the vapour controlling insulation structure 1 is 1/0,15 m²K/W.
If a fire would occur under the load supporting profiled steel plate structure 2, the first insulation layer 3 will for a significant period of time prevent the heat and the flames in reaching the combustible vapour membrane 4. This will save lives among occupants of the building below the vapour controlling insulation structure and also firefighters in their effort to save lives and values from the flames.

List of Reference Numerals

1: vapour controlling insulation structure
2: load supporting structure
3: first insulation layer
4: vapour controlling membrane
5: second insulation layer
6: top surface
7: intermediate surface
8: insulation board
9: sublayers
10: intermediate sublayer surface

A: area
t: thickness

Claims

A vapour controlling insulation structure (1) for a flat or low slope warm roof with a load supporting structure (2), comprising
a first insulation layer (3), a vapour controlling membrane (4), and a second insulation layer (5),

said vapour controlling membrane (4) situated between the first insulation layer (3) and second insulation layer (5),

where said second insulation layer (5) exhibits a top surface (6) with an area (A) adapted for mounting of a roofing membrane,

where the first insulation layer (3) exhibits an intermediate surface (7), said intermediate surface (7) adapted for mounting of said vapour controlling membrane (4), and

where the first insulation layer (3) is with a thickness (t) and constituted by one or more insulation boards (8),

characterized in that

said second insulation layer (5) is constituted by two stacked sub-layers (9) both with substantially the same thickness (t) as the first insulation layer (3).
The vapour controlling insulation structure (1) according to claim 1, wherein the two stacked sub-layers (9) are each constituted by one or more insulation boards (8) of the same material and with the same material dimensions and material properties as the insulation boards (8) constituting the first layer (3).
The vapour controlling insulation structure according to claim 2, wherein the insulation boards (8) are box-shaped and are symmetric relative to a centre point in respect of material properties and dimensions.
The vapour controlling insulation structure according to claim 2 or 3, wherein both of the sublayers (9) of the second insulation layer (5) exhibits an intermediate sublayer surface (10) each with an area equal to the area (A) of the top surface (6).
The vapour controlling insulation structure according to any one of the preceding claims, wherein the insulation board is made of mineral wool, preferably glass wool.
The vapour controlling insulation structure according to any one of the preceding claims, wherein the load supporting structure (2) is constituted by profiled steel plates.
The vapour controlling insulation structure according to any one of the preceding claims, wherein the compressive strength of said insulation board in a direction perpendicular to the top surface (6) is above 20 kPa, preferably between 25-80 kPa.
The vapour controlling insulation structure according to any one of the preceding claims, wherein two or more insulation boards (8) are adapted to be positioned directly on the load supporting structure (2), wherein the two or more insulation boards (8) are placed side-by-side constituting the first insulation layer (3) exhibiting an intermediate surface (7) with an area (A) adapted for mounting of a vapour controlling membrane (4), where a further number of insulation boards (8) are placed side-by-side constituting a sublayer (9) as the lower part of the second insulation layer (5) constituting an intermediate sublayer surface (10) adapted for positioning a further number of insulation boards (8) placed side-by-side, constituting another sublayer (9) being the upper half of the second insulation layer (5), and constituting a top surface (6) with an area (A) adapted for mounting of a roofing membrane.
The vapour controlling insulation structure (1) according to any one of the preceding claims, wherein the R-value of said one or more insulation boards (8) is one third of the required R-value of the insulation layers (3,5) in the vapour controlling insulation structure (1).
The vapour controlling insulation structure (1) according to any one of the preceding claims, wherein the R-value of the vapour controlling insulation structure (1) is 1/0,15 m²K/W.
A method of laying a vapour controlling insulation structure (1) on a load supporting structure (2), comprising the consecutive steps of
positioning one or more insulation boards (8) with a thickness (t) on a load supporting structure (2), such as a profiled steel structure for a warm roof, whereby an intermediate surface (7) is constituted;

positioning a vapour control membrane (4) on the intermediate surface (7);

positioning one or more of the insulation boards (8) with the thickness (t) on the vapour control membrane (4) whereby an intermediate sublayer surface (10) is constituted; and

positioning one or more of the insulation boards (8) with the thickness (t) on the intermediate sublayer surface (10) whereby a top surface (6) with an area (A) is constituted and adapted for mounting of a roofing membrane.
The method according to claim 11, wherein the insulation boards (8) for the two sublayers are taken from the same pallet and placed in the second insulation layer (5).