The present invention relates to a construction product, a method of preparation, and a method of application of the product. In particular, the present invention is concerned with a tree-based construction product,such as cork, that acts as an insulating material, and associated methods.

Appropriate thermal insulation of buildings is important to retain heat and thereby reduce energy costs. The use of insulating materials can be helpful in reducing carbon emissions and their negative impact on the environment.

Typical thermal insulation materials for buildings include natural and synthetic fibres, and also foams which are often used in roofs, walls and floors.

Cork is a natural material that is harvested from the barks of trees, such as from the cork oak tree. Cork is known as a good insulator, which is largely due to its microscopic structure. The cork cells comprise air which can inhibit the transfer of heat through the cork.

Aerogels are also known in the art for being good insulators. Aerogels are a highly porous, ultra-light synthetic material made from gels by replacing the solvents on the gel with air. This material has very low density and low thermal conductivity due to its mesopores typically being 50 nm or less. This structure also resists heat transfer through conduction, convection and radiation. However, because the aerogels have low mechanical resistance and are brittle, they are difficult to work with and to apply to building surfaces including walls, floors and ceilings.

A poorly applied layer of aerogel, or any type of insulation, can lead to so-called cold bridges, or thermal bridges, which allow the transmission of heat and build-up of moisture leading to poor energy performance.

When applying insulation wet, water and surfactants can be added to an aerogel insulating mixture to make it more workable. However, if the water content in the insulation mixture is too great initially, cracking of the insulation can also occur as it dries, due to the hygroscopic nature of the aerogel.

Ideally, insulation is installed during the construction of the building, so that it can be easily applied and then hidden once installed.

However, older, poorly insulated buildings also require insulation to be retrofitted, for example by applying an insulating layer over the walls of a room. A common problem with this, when applying to the internal surfaces of the walls, is the ensuing reduction in room size that retrofitting insulation causes. Layers of insulating materials must be installed which are then typically covered in plaster board/drywall and then skimmed over with a thin layer of plaster before a decorative finish is applied. Not only does the extra wall thickness introduced reduce the volume of the room, but certain types of fixtures and fittings, such as radiators and electrical sockets for example, must be moved and refitted after the installation, increasing the total cost and time scale of the project. A further problem is that when applying insulation around windows, the amount of light that enters a room may be reduced.

In the case of many older buildings whose walls are constructed without a cavity and which are designed for water vapour to pass through, the retro-applied installation of vapour-closed insulation materials prevents walls functioning as designed, with the consequent risk over time of moisture build-up within the walls which can cause rot, mould, condensation and reduce the thermal performance of the wall.

Embodiments of the present invention aim to provide an insulating material, and a method of mixing and applying the material, in which at least some of the aforementioned problems are addressed.

The present invention is defined in the attached independent claims, to which reference should now be made. Further, preferred features may be found in the sub-claims appended thereto.

According to one aspect of the present invention, there is provided a thermal insulation material for application onto a building surface, wherein the material comprises a mixture of at least 2% by weight of aerogel, at least 4% by weight of a tree-based component and at least 50% by weight of binder.

Preferably the mixture may comprise at least 3% by weight of aerogel, more preferably at least 6%. Preferably the mixture may contain at least 6% by weight of tree-based component, more preferably at least 8% by weight of tree- based component. Preferably the mixture may comprise at least 60% by weight of binder, more preferably at least 75% by weight of binder.

The mixture may be vapour permeable when applied.

According to another aspect of the present invention, there is provided a thermal insulation material for application onto a building surface, wherein the material comprises a mixture of tree-based component, aerogel and a binder, wherein the mixture is vapour permeable when applied.

According to another aspect of the present invention there is provided a thermal insulation material for application onto a building surface, the material comprising a mixture of a tree-based component, aerogel, and binder, wherein the binder is vapour permeable.

The binder may comprise an acrylic emulsion. The tree- based component may comprise cork.

The mixture may comprise at least 2% by weight of aerogel, at least 4% by weight of cork and at least 50% by weight of binder. Preferably the mixture may comprise at least 3% by weight of aerogel, more preferably at least 6%. Preferably the mixture may contain at least 6% by weight of cork, more preferably at least 8% by weight of cork. Preferably the mixture may comprise at least 60% by weight of binder, more preferably at least 75% by weight of binder .

The cork may be in granular form. The binder may be diluted with water and/or wetting agents. The aerogel in the mixture may have an average particle size within the range of 100-3500 pm. Prefereably, the aerogel in the mixture may have an average particle size within the range of 500-3500 pm. Even more preferably, the aerogel in the mixture may have an average particle size within the range of 1000-3500 pm.

The mixture may comprise cork, aerogel, and diluted binder only .

The mixture may have anti-mould and/or anti-condensation properties .

According to a further aspect of the present invention, there is provided a method for preparing a thermal insulating material, the method comprising mixing together a tree-based component and aerogel in a substantially dry state and then adding a vapour permeable binder. The binder is preferably diluted with water and/or a wetting agent before adding to the cork and aerogel mixture .

The tree-based component may comprise cork. The vapour permeable binder may comprise an acrylic emulsion.

The mixing may take place on site and may take place immediately prior to use of the mixture.

In another aspect, the present invention provides a method of thermally insulating at least a portion of a building surface, the method comprising the steps of applying to the building surface an insulating material comprising a mixture of a tree-based component, aerogel and vapour permeable binder and thereafter applying a layer of plaster material onto the insulating material.

The tree-based component may comprise cork. The vapour permeable binder may comprise an acrylic emulsion.

The thermal insulating material may comprise at least 2% by weight of aerogel, at least 4% by weight of cork and at least 50% by weight of binder. Preferably the mixture may comprise at least 3% by weight of aerogel, more preferably at least 6% by weight of aerogel. Preferably the mixture may contain at least 6% by weight of cork, more preferably at least 8% by weight of cork. Preferably the mixture may comprise at least 60% by weight of binder, more preferably at least 75% by weight of binder.

Preferably, the method comprises applying the plaster material directly to the insulating material. In a preferred arrangement, the method includes allowing the insulating material to dry substantially before applying the plaster material.

The method may comprise skimming the plaster material after, and/or during applying it to the insulating material.

The method may comprise applying the insulating material to an internal wall of a building.

Preferably the skimmed plaster has a thickness of 1-3 mm. Preferably the insulating material is applied to the wall by spraying. Alternatively or additionally, the material is applied to the wall by trowelling.

The thickness of the insulating material may be of a range of 2-25mm. More preferably the thickness of the insulating material may be of a range of 4-8 mm.

The invention may include any combination of the features or limitations referred to herein, except such a combination of features as are mutually exclusive, or mutually inconsistent.

A preferred embodiment of the present invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings, in which:

Figure 1 shows a schematic section of part of a wall with retrofitted insulation according to prior art; and

Figure 2 shows a schematic section of part of a wall with retrofitted insulation according to an embodiment of the present invention.

Turning to Figure 1, in accordance with a previously considered retro-fit insulation process, a wall to be insulated is shown generally at 100. A layer of insulating material 110 lies on the wall surface. On top of the insulating material is a portion of plaster board 120, onto which has been skimmed a thin layer of plaster 130. The cumulative thickness of these layers is represented by T.

Turning to Figure 2, the wall to be insulated is shown generally at 200. Applied to the wall 200 is a layer of insulating material 210, in accordance with an embodiment of the present invention. On top of the insulating mixture is a layer of skimmed plaster 230. The thickness of the cumulative layers of insulator and skimmed plaster is represented by T'. T' is of a shorter length than T of Figure 1. Insulating material 210 has a thickness of less than 25 mm, more preferably a thickness of less than 4- 8mm.

The insulating material layer 210 is a mixture of cork granules, aerogel and binder. The cork granules comprise natural cork with particle size of 0.5-2mm in diameter. The aerogel may have an average particle size of 100-3500 pm. Preferably, the aerogel may have an average particle size of 500-3500 pm. Even more preferably, the aerogel may have an average particle size of 1000-3500 pm. The binder may be a vapour permeable acrylic emulsion.

The present invention allows for the application of an effective insulation layer onto surfaces of a room, which layer can be applied during the construction of a building or else can be retrofitted to an existing building. The insulating material comprises a relatively thin layer that does not significantly reduce the volume of a room when applied to its walls, nor does it require the movement or replacement of any fixtures and fittings.

The insulating layer thus formed is vapour permeable and relatively smooth, which allows plaster to be skimmed straight onto it when it has substantially dried. This eliminates the need for any levelling work to be carried out and/or plasterboard to be installed over the insulation prior to a final skim, thus saving time and cost. Because of the permeability of the insulating material, when the plaster is skimmed on top of the insulation, the plaster can dry out at an optimal rate to provide a good bond to the insulation, without cracking.

A further benefit of the insulation being vapour permeable is that it allows for moisture control within a building. This is especially beneficial when the insulation is fitted to an already breathable wall, so as to preserve this feature and prevent condensation and/ or rotting of timbers within the wall.

Embodiments of the present invention obviate the need for surfactants to be used in the insulating mixture.

Embodiments of the present invention have demonstrated increased thermal performance over the prior art.

Insulating material according to embodiments of the present invention comprises aerogel which has been mixed in a way so that it can be applied by spraying, or trowelling .

The mixture also comprises the natural component cork, which is a carbon-negative product. The harvesting of cork does not require mature trees to be felled and instead encourages the trees to absorb more carbon by regrowing their cork bark after each harvest.

The low water content of the material further reduces the possibility of the insulating mixture cracking as it dries after application.

The composition of the mixture allows it to be flexible, strong, and to adhere to a range of different surfaces, such as plaster and stone.

Furthermore, the material is economical to manufacture, to store and to apply. Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance, it should be understood that the applicant claims protection in respect of any patentable feature or combination of features referred to herein, and/or shown in the drawings, whether or not particular emphasis has been placed thereon.