Field of the Invention

The present invention relates to the field of building materials.

Background of the Invention

It is generally a problem to avoid the formation of cold conductors throughout a building construction, such as walls, the floor, or the roof. Even when the construction comprises wood, the wood itself must be considered to contribute to the forming of cold conductors.

EP1662057 discloses a solution where the building construction is made of a framework in the form of a wooden lattice construction as a support for suitable cladding parts. The building construction comprises a wooden framework, which includes a wooden batten, which is built up of two or more single battens, which are joined together with one or more insulation layers lying between them, or which includes wooden elements, which are divided into two or more partprofiles, which are assembled with intermediate insulation plates. The idea is to reduce the through-going parts of wood. However, such a framework of wooden battens is difficult to construct and is not suitable for all types of building constructions.

Object of the Invention

The objective of the present invention is to provide a solution that solves at least some of the above problems.

Description of the Invention

The inventor has built a laminated building material, which can be used as a post, a beam, a stud, a joist, a rafter, or the like building material and which minimizes the thermal conductance across the material. A first aspect relates to a laminated building material comprising:

- a first layer of a suitable material, such as solid wood, metal, or engineered wood, and with a thickness of at least 20 mm;

- a second layer of a suitable material, such as solid wood, metal, or engineered wood, and with a thickness of at least 20 mm; and

- a third layer with a thickness of at least 20 mm, interlaid between and fastened to said first and second layers, being diffusion-open to water vapor, and made from an organic fiber material, such as hemp fibers, wood fibers, and/or flax fibers, said material having a density within the range of 20-300 kg per cubic meter.

In the present context, the term “building material” means a structural element for use in forming part of a building structure, such as a roof, a floor, a fagade, a wall, or the like.

As used in the specification and the appended claims, the singular forms "a",

"an", and "the" include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from "about" or "approximately" one particular value and/or to "about" or "approximately" another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about", it will be understood that the particular value forms another embodiment.

It should be noted that embodiments and features described in the context of one of the aspects of the present invention also apply to the other aspects of the invention.

The invention is described in more detail in the following detailed description of a preferred embodiment, with reference to the figures. Brief description of the figures

Figure 1 is a perspective view of a building structure comprising laminated building materials in accordance with various embodiments of the invention.

Figure 2 is a schematic drawing of a part of a building structure comprising laminated building materials in accordance with various embodiments of the invention.

Figure 3 is a schematic drawing (cross-sectional view) of possible layer connections for a laminated building material in accordance with various embodiments of the invention.

Figure 4 is a schematic drawing (cross-sectional view) of possible layer construct for a laminated building material in accordance with various embodiments of the invention.

References

10 Rafter

20 Top plate

30 Stud

40 Bottom plate

50 Bearer

100 Laminated building material

110 First layer

120 Second layer

122 Slot

130 Third layer

132 Block or beam

134 Air-filled gaps or compartments Detailed Description of the Invention

Figure 1 is a perspective view of a building structure comprising various laminated building materials in accordance with various embodiments of the invention. Common for all the laminated building materials is that they each comprises a) a first layer 110 of a suitable material, such as solid wood, metal, or engineered wood, and with a thickness of at least 20 mm, b) a second layer 120 of a suitable material, such as solid wood, metal, or engineered wood, and with a thickness of at least 20 mm, and c) a third layer 130 with a thickness of at least 20 mm, interlaid between and fastened to said first 110 and second 120 layers, being diffusion-open to water vapor, and made from an organic fiber material, such as hemp fibers, wood fibers, and/or flax fibers, said material having a density within the range of 20-300 kg per cubic meter. The shown examples of building materials are rafters 10, top plates 20, studs 30, bottom plates 40, and bearers 50.

In one or more embodiments, the laminated building material is configured as a post, a beam, a stud, a joist, a rafter, or the like.

Figure 2 is a schematic drawing of a part of a building structure also comprising the first four laminated building materials as shown in Figure 1, and where cross- sectional views are shown for the rafter 10 and the stud 30, as their ends does not show in the depicted viewing angle. Depending on the use and type of building material, the three layers may vary in thickness, but the thickness should not be less than about 20 mm as their function will otherwise be lost. The exemplified rafter 10 is here shown built with a first layer 110 (the outer layer) with a thickness of about 200 mm, a second layer 120 (the inner layer) with a thickness of about 70 mm, and a third layer 130 (the middle layer) with a thickness of about 100 mm. The stud 30, top plate 20, and bottom plate 40 are here shown built with a first layer (the outer layer) with a thickness of about 150 mm, a second layer (the inner layer) with a thickness of about 70 mm, and a third layer (the middle layer) with a thickness of about 100 mm.

The bearer 50 only shown in Figure 1 is exemplified built with a first layer (the upper layer) with a thickness of about 200 mm, a second layer (the lower layer) with a thickness of about 70 mm, and a third layer (the middle layer) with a thickness of about 200 mm. In general, there is no maximum thickness of the three layers, but they will obviously be limited by the dimensions of the building material. Multiple layers of each of the three layers 110, 120, 130 may also be present, with the only limitation that the third layer 130 should always be flaked on both sides by a first 110 or second 120 layer. An example of such a building material could be the two following five-layer constructions: i) first layer-third layer-second layer-third layer-first layer, and ii) first layer-third layer-second layer-third layer-second layer.

The third layer 130 has been developed to block or minimize the thermal conductance across the laminated building material. This effect is secured because the third layer is made of a material being diffusion-open to water vapor and is made from an organic fiber material having a density within the range of 20-300 kg per cubic meter.

The organic fiber material could e.g., be hemp fibers, wood fibers, and/or flax fibers. Suitable examples may e.g., be wood fiber insulation boards from Bischoff + Schafer, sold under the tradenames Flex 50, Multitherm 110 and 140, Wall 140 and 180, Room 150, and Top 180. The materials may be treated with water repellant agents, such as wax, e.g., paraffin wax, or the like. The materials may also be treated with fire retarding substrates, well-known to the skilled person within the field of building materials. Obviously, the first- and second-layer materials may also be treated with both water repellant agents and/or fire retarding substrates. The density of the third layer should be within the range of 20-300 kg per cubic meter, such as within the range of 25-290 kg per cubic meter, e.g., within the range of 30-280 kg per cubic meter, such as within the range of 35-270 kg per cubic meter, e.g., within the range of 40-260 kg per cubic meter, such as within the range of 45-250 kg per cubic meter, e.g., within the range of 50-240 kg per cubic meter, such as within the range of 55-230 kg per cubic meter, e.g., within the range of 60-220 kg per cubic meter, such as within the range of 65-210 kg per cubic meter, e.g., within the range of 70-200 kg per cubic meter, such as within the range of 75-190 kg per cubic meter, e.g., within the range of 80-180 kg per cubic meter, such as within the range of 85-170 kg per cubic meter, e.g., within the range of 90-160 kg per cubic meter, such as within the range of 95- ISO kg per cubic meter, e.g., within the range of 100-140 kg per cubic meter, such as within the range of 105-130 kg per cubic meter, e.g., within the range of 110-120 kg per cubic meter. Preferably, the density of the third layer should be within the range of 40-200 kg per cubic meter.

The first 110 and second 120 layers are preferably made of solid wood or engineered wood, but could also be made of metal, such as metal beams, or a polymer material. Especially when the first 110 and second 120 layers are made of solid wood or engineered wood, it is an advantage that the absorbed water can leave the material again to avoid degradation. This is achieved by the third layer 130 as is diffusion-open to water vapor. Vapor diffusion is the movement of water vapor molecules through porous materials as a result of vapor pressure differences. It’s one of four critical elements that affects the success of your building enclosure.

In the present context, the term “solid wood” refers to timber products, which consist basically of solid wood or solid wood parts, and thus does not include engineered wood, such as Oriented Strand Board (OSB), Medium Density Fiberboard (MDF), plywood, Masonite, or the like. Engineered wood often show to be stronger than solid wood. Flence, for carrying building materials it may be preferred that at least the first layer or the second layer is made of an engineered wood, preferably both.

In one or more embodiments, at least one of said first and second layers, preferably both, are made of solid wood or solid wood panels, such as Glue Laminated Timber (GLT), Laminated Veneer Lumber (LVL), Parallel Strand Lumber (PSL), Laminated Strand Lumber (LSL), Cross Laminated Timber (CLT), Nail Laminated Timber (NLT), or the like.

Alternatively, or in combination, at least one of said first and second layers, preferably both, are made of metal.

When the building material is used for other applications, it may be sufficient that one or both of said first or second layers are made of Oriented Strand Board, Medium Density Fiberboard, plywood, Masonite, or the like.

As discussed, the third layer is configured as a thermal bridge breaker between said first and second layers. Suitable materials should therefore have a relatively low thermal conductivity, i.e. , having a lambda value.

The term “thermal bridge breaker” means any layer of material making it possible to limit the thermal bridge between the first and second material layers by creating a thermal separation, while ensuring mechanical or at least functional continuity between the layers.

The term “lambda value”, as used herein, represents the heat conductivity of a material. The lambda value is used for thermal calculations on buildings and thermal components. The thermal conductivity of a material is defined as the quantity of heat (e.g., Joules) transferred in a given time (e.g., seconds) through a distance L (e.g., meters) in a direction normal to a surface area A (e.g., sq. meter), due to a temperature difference AT (e.g., Kelvin), and when the heat transfer is dependent only on the temperature gradient. One commonly used unit of the lambda value is mW/mK (i.e. , milliwatt per meter Kelvin).

In one or more embodiments, the third layer is configured as a thermal bridge breaker between said first and second layers and having a thermal conductivity, i.e., having a lambda value, of at most 100 milliwatt per meter Kelvin, but preferably lower, such as within the range of 20-50 milliwatt per meter Kelvin. Typical solid wood has a thermal conductivity of about 140 milliwatt per meter Kelvin. The density of a material may affect its thermal conductivity. As an example, the thermal conductivity of MDF varies from 50 mW/mK for a panel density of 250 kg/m ³ to 140 mW/mK for a panel density of 800 kg/m ³ . Hence, the density of the third layer material must be within the range of 20-300 kg per cubic meter, preferably, within the range of 40-200 kg per cubic meter. Such materials are preferably made from compressed organic fibers, such as hemp fibers, wood fibers, and/or flax fibers.

As previously said, the third layer should preferably ensure mechanical or at least functional continuity between the layers. In order to aid the connection of the layers, the third layer may be fastened to said first and second layers by a joint (see e.g., Figure 3) formed in said layers, such as a finger joint, a tongue and groove joint, and the like. The protrusions of such joints may be barbed, as shown to the left of Figure 3B. In addition, the joints may be strengthened by an adhesive. Such adhesives are well-known within the art of building materials.

In one or more embodiments, the third layer is fastened to said first and second layers by an adhesive. Such adhesives are well-known within the art of building materials. A formed joint as discussed above may not be necessary.

Figure 4 is a schematic drawing (cross-sectional view) of possible layer construct for a laminated building material in accordance with various embodiments of the invention. Here, the third layer 130 interlaid between and fastened to the first 110 and second 120 layers comprises multiple blocks or beams of an organic fiber material, such as hemp fibers, wood fibers, and/or flax fibers, said material having a density within the range of 20-300 kg per cubic meter. These blocks or beams 132 are divided by air-filled gaps or compartments 134, preferably of a width and length substantially corresponding to the width and length of blocks or beams 132. The air-filled gaps or compartments 134 are present to make the entire laminated building material more flexible. A further method of inducing flexibility into the laminated building material could be to form elongate slots 122 into the second layer 120, preferably at a position below the air-filled gaps or compartments 134.

In one or more embodiments, the third layer comprises multiple blocks or beams of an organic fiber material, such as hemp fibers, wood fibers, and/or flax fibers, said material having a density within the range of 20-300 kg per cubic meter; and wherein said blocks or beams are divided by air-filled gaps or compartments.

In one or more embodiments, the width and length of said air-filled gaps or compartments substantially corresponds to the width and length of said blocks or beams.

In one or more embodiments, the second layer comprises elongate slots.

In one or more embodiments, the elongate slots are positioned within the second layer below or above the air-filled gaps or compartments, depending on the use position of the laminated building material.

In one or more embodiments, the elongate slots are positioned within the second layer below the air-filled gaps or compartments.

In one or more embodiments, the elongate slots are positioned within the second layer above the air-filled gaps or compartments. A second aspect of the present invention relates to the use of a laminated building material according to the present invention for constructing a building, wherein said laminated building material is positioned such that the first layer faces towards the inside of the building or building envelope and wherein said second layer faces away from the building envelope. This positioning is important to make the third layer function as a thermal bridge breaker.