GB2542110A

GB2542110A - Improved timber frame insulating elements

Info

Publication number: GB2542110A
Application number: GB1511556.1A
Authority: GB
Inventors: Mary Lancaster Eileen; Thomas Edwards Robert; John Woodley Bryan
Original assignee: Scotframe Timber Engineering Ltd
Current assignee: Scotframe Timber Engineering Ltd
Priority date: 2015-07-01
Filing date: 2015-07-01
Publication date: 2017-03-15
Anticipated expiration: 2035-07-01
Also published as: GB201511556D0; GB2542110B

Abstract

An insulating timber frame building element (10) defining at last one cavity (22) and comprises a polymeric foam (42) within the at least one cavity (22), wherein the polymeric foam (42) is formed within the at least one cavity (22) from a polymeric foam precursor (38). The polymeric foam precursor (38) is expanded within the at least one cavity (22) by a blowing agent. The blowing agent substantially comprises pentane (n-pentane, iso-pentane, cyclo-pentane or mixtures thereof). Further blowing agents which may be used in addition to pentane are methyl formate, formic acid, hexane, heptane, water, CO2, sodium bicarbonate, titanium hydride, light alcohols, ketones and ethers. The polymer may be selected from addition polymers (e.g. polystyrene) or condensation polymers (e.g. polyurethane or polyisocyanate). Some aspects of the invention relate to the field of fabricating elements for building thermally insulated homes.

Description

Improved timber frame insulating elements Field of the Invention

The present invention relates to the field of thermal insulation in construction of buildings and other structures forming an enclosed space, more particularly to the field of thermal insulation in residential building construction. Some aspects of the invention relate to the field of fabricating elements for building thermally insulated homes.

Background to the Invention

In an effort to produce affordable housing in cold regions many constructors choose insulated timber frame walls and roofs to form the enclosure for their buildings.

Insulated timber frame walls can be made in-situ, where the construction is taking place, or can be pre-fabricated in a dedicated facility and delivered to the construction site ready to be deployed.

The most straightforward method of producing insulated timber frame elements is to insert an insulating medium, which is normally a rigid polymeric foam sourced from a third party, within the timber frame wall or roof before closing the wall with a cover element. This method is straightforward but can be costly and time consuming.

Some insulated timber frame wall providers use a variant of the process, in which they build the timber frame structure, defining a cavity and subsequently inject a rigid plastic foam precursor within the cavity that sets or solidifies to form the insulating rigid polymeric foam. This method is more suitable where the demand of timber frame insulating elements is high and justifies the cost of preparing such a facility to produce cheaper insulating timber frame elements.

The method of producing injected timber frame elements normally uses a polyurethane (or other plastic type) precursor mix containing a blowing agent that will expand the polymeric matrix to fill up the cavity and provide the cellular structure to the matrix that is needed to create an effective insulation barrier. The polyurethane precursors are polyol and isocyanate.

The blowing agents initially used by timber frame insulating element producers were chlorofluorocarbons (CFC’s) because they were economical, non-flammable and low boiling point liquids that could expand into a gas with a low amount of energy input and at low temperatures. Chlorofluorocarbons were phased out in industrialised countries due to environmental concerns in relation to the damaging effects to the atmospheric ozone layer.

Insulating timber frame element manufacturers replaced CFC’s by the non-ozone depleting, more expensive, equally non-flammable and similarly low boiling point hydrofluorocarbons (HFC’s), like the Solkane™ 365/227 manufactured by Solvay. However, these HFC’s are significantly more expensive than the previous CFC’s, their insulating properties, in addition, being worse than the CFC’s.

Summary of the Invention

According to a first aspect of the invention there is provided an insulating timber frame building element defining at last one cavity and comprising a polymeric foam within the at least one cavity, the foam being formed within the at least one cavity from a polymeric foam precursor; wherein the polymeric foam precursor is expanded within the at least one cavity by a blowing agent, the blowing agent substantially comprising at least one compound selected from the group of normal-pentane (n-pentane), isopentane and cyclo-pentane or mixtures thereof.

In at least one embodiment of the present invention a blowing agent comprising light saturated hydrocarbons, such as n-pentane, cyclo-pentane and iso-pentane, is less costly than a halogenated blowing agent. Additionally light saturated hydrocarbons have less environmental fingerprint than CFC’s and HFC’s because they are not ozone depleting and produce less greenhouse effect in the atmosphere.

The primary considerations according to the conventional thinking within the industry have been that the blowing agents should be low cost, volatile and non-flammable. Such a blowing agent assists in making the products economical and straightforward to manufacture because the volatile nature of the blowing agent assists in the transition to gas and the non-flammability reduces the risk of explosion. The use of a flammable blowing agent is therefore counterintuitive, particularly when combined with the fact that the pentane blowing agents are more thermally conductive than conventional blowing agents. For these reasons it is counterintuitive and outwith established practice to use light saturated hydrocarbons such as those from the group of n-pentane, iso-pentane and cyclo-pentane or mixtures thereof.

In fact, a timber frame comprising a polymeric foam expanded by light saturated hydrocarbons may not need to be as thick as a conventionally expanded foam because more biowing agent can be added while keeping a low cost and the extra blowing agent wouid have less thermal conductivity than the polymeric foam that the biowing agent repiaces.

The polymeric foam may be a rigid polymeric foam.

The polymeric foam may be a closed cell polymeric foam.

Alternatively the polymeric foam may be an open cell polymeric foam.

The polymeric foam may comprise addition polymers.

Additionally or alternatively the polymeric foam may comprise condensation polymers.

The polymeric foam may comprise a polyurethane foam.

Additionally or alternative the polymeric foam may comprise a polyisocyanurate foam. Polyisocyanurate foams show enhance flame-retardant properties.

Alternatively or additionally the polymeric foam may comprise an expanded polystyrenic foam.

Other suitable polymers may be used to form the polymeric foam, for example extruded polystyrene foam, urea-formaldehyde foam, urea foam, phenolic foam, cementitious foam, etc.

Other hydrocarbons may form part of the blowing agent, for example methyl formate or formic acid among others.

Other hydrocarbons may be used to adjust the volatility of the blowing agent to adjust the foam cell size in the finished product, for example hexane, heptane or their isomers.

Other non-hydrocarbon components may form part of the blowing agents, such as water, carbon dioxide, bicarbonate of soda, titanium hydride or mixtures thereof, to name a few.

Other non-hydrocarbons may be used to adjust the volatility of the blowing agent to adjust the foam cell size in the finished product, for example light alcohols, ketones or ethers.

The polymeric foam precursor may be formed by mixing one or more monomeric components and the blowing agent.

The monomeric component or components may be one or more addition monomeric components.

Alternatively the monomeric components may be condensation monomeric components.

The polymeric foam precursor may be formed by mixing polyol with the blowing agent and isocyanate.

The polymeric foam precursor may be formed by mixing polyol with the blowing agent and isocyanurate.

The polymeric foam precursor may be formed by mixing vinylic monomers.

The polymeric foam precursor may comprise plasticisers.

The polymeric foam precursor may be formed by mixing styrenic monomers, such as styrene.

The polymeric foam precursor may comprise a cross-linking or reticulating agent, such as glycerol or formaldehyde among others.

The polymeric foam precursor may comprise a catalyst or catalyst mixture to facilitate polymerisation and/or hardening of the polymeric foam precursor.

Catalysts for polyurethane polymerisation can be classified into two broad categories, amine compounds and organo-metallic compounds. Traditional amine catalysts are tertiary amines such as triethylenediamine (TEDA, 1,4-diazabicyclo [2.2.2] octane or DABCO), dimethylcyclohexylamine (DMCHA), and dimethylethanolamine (DMEA). Metallic compounds based on lead, tin, bismuth, and zinc are used as polyurethane catalysts too.

The polymeric foam precursor may comprise a flame-retardant agent. Flame-retardant agents may be mineral, organohalogenated or organophosphorated compounds. Among suitable flame retardant agents are aluminium oxide; chlorendic acid derivatives and chlorinated paraffins; organobromines such as decabromodiphenyl ether; triphenyl phosphate (TPP), resorcinol bis(diphenylphosphate) (RDP), bisphenol A diphenyl phosphate (BADP), and tricresyl phosphate (TCP).

The insulating timber frame building element may comprise a plaster board for providing fire retardant properties to the timber frame building element.

The insulating timber frame building element may be configured to act as a building wall.

Alternatively the insulating timber frame building element may be configured to act as a building roof.

Alternatively the insulating timber frame building element may be configured to act as a ceiling.

Alternatively the insulating timber frame building element may be configured to act as a floor.

Alternatively the insulating timber frame building element may be configured to act as a building partition.

The insulating timber frame building element may define apertures to accommodate windows, doors or other type of apertures known in the building construction field.

The insulating timber frame building element may define a plurality of cavities configured to receive a predetermined amount of polymeric foam precursor.

The insulating timber frame building element may be planar.

The insulating timber frame building element may be a panel.

Alternatively the insulating timber frame building element may be curved.

Alternatively the insulating timber frame building element may comprise planar and curved sections.

According to a second aspect of the invention there is provided a method for producing an insulating timber frame building element, the method comprising the steps of: providing a timber frame element defining at least one cavity; providing a polymeric foam precursor comprising a blowing agent substantially comprising at least one compound selected from the group of n~ pentane, iso-pentane and cyclo-pentane or a mixture thereof; introducing the polymeric foam precursor into the at least one cavity; expanding the polymeric foam precursor by the effect of volatilisation of the blowing agent while the polymeric foam precursor fills the at least one cavity and polymerises into a polymeric foam within the at least one cavity.

In at least one embodiment of the present invention the method of producing insulating timber frame building elements described before is less costly than the methods known in the state-of-the-art and is less harmful to the environment because the pentane isomers have no ozone depleting capacity and less greenhouse effect that the conventional halogenated blowing agents.

However, implementing the previously described method might be considered discouraging due to the fact that pentanes are highly flammable and present a higher thermal conductivity than the halogenated blowing agents.

The method may comprise flushing the air in the at least one cavity with an inert gas prior to introducing the polymeric foam precursor within the cavity.

In at least one embodiment of the present invention this step enhances the inherent safety of the method because it avoids the formation of explosive mixtures of air and hydrocarbon vapours.

The inert gas may be nitrogen. Pure nitrogen can be generated from air in-situ on demand with appropriate equipment and there is no need for an external nitrogen supply. Other inert gases may be used, such as neon, carbon dioxide, etc.

The method may comprise the step of mixing the components of the polymeric foam precursor just before introducing the polymeric foam precursor into the at least one cavity. In at least one embodiment of the present invention this step is just before injection into the cavity to avoid reaction and hardening of the ingredients of the polymeric foam precursor outside the cavity.

The method may comprise selecting and/or adjusting the pressure at which the polymeric foam precursor is introduced in the cavity.

The method may comprise selecting and/or adjusting the rate at which the polymeric foam precursor is introduced in the cavity.

The method may comprise selecting and/or adjusting the ratio of the components of the polymeric foam precursor.

The method may comprise the step of mixing the hydrocarbon containing blowing agent with a component of the polymeric foam precursor before mixing it with the other components of the polymeric foam precursor. In at least one embodiment of the present invention this may favour an homogeneous dispersion of the blowing agent in the polymeric foam precursor.

According to a third aspect of the invention there is provided an insulating timber frame building element defining at last one cavity and comprising a polymeric foam within the at least one cavity, the foam being formed within the at least one cavity from a polymeric foam precursor; wherein the polymeric foam precursor is expanded within the at least one cavity by a blowing agent substantially comprising at least one compound selected from the group of light non-halogenated liquid hydrocarbons or mixtures thereof.

According to a fourth aspect of the invention there is provided an insulating timber frame building element defining at last one cavity and comprising a polymeric foam within the at least one cavity, the foam being formed within the at least one cavity from a polymeric foam precursor; wherein the polymeric foam precursor is expanded within the at least one cavity by a blowing agent substantially comprising at least one compound seiected from the group of Sight saturated liquid hydrocarbons or mixtures thereof.

According to a fifth aspect of the invention there is provided a method for producing an insulating timber frame building element, the method comprising: providing a timber frame element defining at least one cavity; providing a polymeric foam precursor comprising a blowing agent substantially comprising at least one compound selected from the group light non-halogenated liquid hydrocarbons or mixtures thereof; introducing the polymeric foam precursor into the at least one cavity; expanding the polymeric foam precursor by the effect of volatilisation of the blowing agent while the polymeric foam precursor fills the at least one cavity and polymerises into a polymeric foam within the at least one cavity.

According to a sixth aspect of the invention there is provided a method for producing an insulating timber frame building element, the method comprising: providing a timber frame element defining at least one cavity; providing a polymeric foam precursor comprising a blowing agent substantially comprising at least one compound selected from the group of light saturated liquid hydrocarbons or mixtures thereof; introducing the polymeric foam precursor into the at least one cavity; expanding the polymeric foam precursor by the effect of volatilisation of the blowing agent while the polymeric foam precursor fills the at least one cavity and polymerises into a polymeric foam within the at least one cavity.

Any aspect of the invention may include features of other aspects of the invention and are not repeated for brevity.

Brief Description of the Drawings

Some embodiments of the present invention will be described below making reference to the accompanying drawings, in which:

Figure 1 represents a timber frame building element comprising several cavities.

Figure 2 represents the timber frame building element of Figure 1 in which one of the cavities is being flushed with an inert gas, such as nitrogen.

Figure 3 represents the timber frame building element of Figure 2 in which the cavity flushed with nitrogen is being filled with polymeric foam precursor mixed with a mixture of pentanes as blowing agents.

Figure 4 represents the timber frame building element of Figure 3 in which all the cavities have been filled with polymeric foam precursor and the blowing agent has expanded and the polymeric foam has filled the cavities and hardened.

Figure 5 represents a schematic diagram of the facility used to prepare the polymeric foam precursor.

Detailed Description of the Drawings

Figure 1 represents a timber frame building panel or element, indicated generally by reference numeral 10. The timber frame element 10 is made by joining external timber beams 12 which forming the load bearing structure of the panel 10. By adding additional internal timber beams 14, the space defined by the external timber beams 12 is divided into smaller areas 16. Other secondary timber beams 18 are used to define apertures 20 in the panel which will eventually receive windows, doors or other features.

Once the panel frame is formed, it is covered with plywood panels (not shown) on both sides, such that enclosed cavities 22 are defined where the areas 16 where defined by the panel frame beams.

The timber beams 12,14,18 are joined together by nails and glue, although other joining methods can be used, such as with dovetail connections or other known interlocking profiles. The beams can be equally made of other materials, but timber is a suitable affordable material. The plywood panels can also be replaced by panels of other materials, such as agglomerated boards, plaster, etc.

Once the timber frame panel 10 have been formed, orifices 24 are created at each side of each cavity 22 such that the following manufacturing steps can be performed. Some of the orifices 24 are for introducing material and some are for air outflow and for checking that the cavities are filled up.

Figure 2 represents the timber frame panel 10 of Figure 1 in which nitrogen gas 26 is being introduced with a nozzle 28 through an orifice 24 into a cavity 22 such that air 30 present in the cavity 22 is displaced or flushed out of the cavity 22 through another orifice 32. This step is done to improve the safety of the following manufacturing step, in which a foam precursor containing flammable material is introduced in the cavity.

Figure 3 shows a sectional side view of the panel 10 along section A-A’, as indicated in Figure 1. In Figure 2 we can see orifice 24, the nozzle 28, and a cavity 22 defined by external beam 12 and plywood boards 34, 36. A polymeric foam precursor 38 is being introduced into the cavity 22 through the orifice 24 with the nozzle 28. The polymeric foam precursor 38 is produced using isopentane (10-30% weight) and cyclo-pentane (70-90% weight) mixtures as blowing agent, with an iso-pentane to cyclo-pentane preferred weight ratio of 20:80. The polymeric foam precursor 38 is produced by mixing the blowing agent mixtures at 5-10% weight with less than 5% weight in catalyst and with polyol in a closed circuit with a buffer vessel and mix the resulting blowing agent-catalyst-polyol mixture with the isocyanate, immediately before injection to the timber frame cavity, in a mass ratio between 100:110 to 100:130, with a ratio of 100:120 being preferred. The polymeric foam precursor is introduced into the timber frame cavity at a rate of between 400 g/s and 1600 g/s and a pressure of between 100 - 140 bar (10 - 14 MPa) (preferred pressure 130 bar, i.e. 13 MPa) and at a temperature range from 18 to 22 °C, with a temperature of 20°C being preferred.

Whilst not wishing to be bound by theory, the applicant believes that the exothermic reaction between the polyol and the isocyanate provides enough heat to volatilise the pentane mixture, thus creating pentane microbubbles in the polymeric matrix and expanding it to fill the cavity without leaving any empty gap. Once the polymer has reacted completely, a rigid polymeric matrix with millions of embedded pentane microbubbles is formed which has an appropriate low thermal conductivity to act as a building insulating material.

Figure 4 shows the resulting insulating timber frame building element 40 with the polymeric rigid foam sheets 42.

Figure 5 is a schematic representation of the facility used to prepare the polymeric foam precursor that is injected to the cavities to form the polymeric insulating foam. The pentane mix is stored in a pressurised vessel 52 which is protected by nitrogen blanketing and located in a conveniently ventilated area. The pressurised vessel 52 is equipped with overpressure security measures.

The pentane mix is blended with the polyol and kept is constant circulation in a closed circuit with a buffer vessel 54, which is also nitrogen blanketed. The isocyanate mix is kept in constant circulation in another closed circuit with the corresponding buffer vessel 56.

Nitrogen is obtained from the air with the nitrogen generator 58, which supplies a nitrogen stream to the blanketed vessels 52, 54 and to the injection nozzle 60.

The polymeric foam precursor is formed by mixing the isocyanate mix with the polyol and blowing agent mix and a catalyst at the mixing head 62. The mixing head 62 is adapted to control the pressure, injection rate and ratio between both components of the mixture that form the polymeric foam precursor. The mixing head 62 feeds the nozzle 60 which introduced the foam precursor into the timber frame cavities.

The mixing head is also 62 fitted with an additional port to supply pure nitrogen to flush the air from the timber frame panel cavities.

Various modifications of the previous example are also considered to fall within the scope of the invention as herein intended, in particular different compositions of blowing agents and polymeric foam precursor, as well as different injection parameters such as pressure, injection rate and temperature may also be employed without departing from the principles of the invention and the embodiment previously described is merely for illustrative purpose.

Claims

1. An insulating timber frame building element defining at last one cavity and comprising: a polymeric foam within the at least one cavity, the polymeric foam being formed within the at least one cavity from a polymeric foam precursor; wherein the polymeric foam precursor is expanded within the at least one cavity by a blowing agent, the blowing agent substantially comprising at least one compound selected from the group of normal-pentane (n-pentane), iso-pentane and cyclo-pentane or mixtures thereof.

2. An insulating timber frame building element as claimed in claim 1, wherein the polymeric foam is a rigid polymeric foam.

3. An insulating timber frame building element as claimed in claim 1, wherein the polymeric foam is a closed cell polymeric foam.

4. An insulating timber frame building element as claimed in claim 1, wherein the polymeric foam is an open cell polymeric foam.

5. An insulating timber frame building element as claimed in any one of the preceding claims, wherein the polymeric foam comprises addition polymers.

6. An insulating timber frame building element as claimed in any one of the preceding claims, wherein the polymeric foam comprises condensation polymers.

7. An insulating timber frame building element as claimed in claim 1, wherein the polymeric foam comprises a polyurethane foam.

8. An insulating timber frame building element as claimed in any preceding claim, wherein the polymeric foam comprises a polyisocyanurate foam.

9. An insulating timber frame building element as claimed in any preceding claim, wherein the polymeric foam comprises an expanded polystyrenic foam.

10. An insulating timber frame building element as claimed in claim 1, wherein the polymeric foam is formed from one or more of the following: extruded polystyrene foam, urea-formaldehyde foam, urea foam, phenolic foam or cementitious foam.

11. An insulating timber frame building element as claimed in claim 1, wherein the blowing agent is formed of methyl formate.

12. An insulating timber frame building element as claimed in claim 1, wherein the blowing agent is formed of formic acid.

13. An insulating timber frame building element as claimed in claim 1, wherein the blowing agent is formed of hexane.

14. An insulating timber frame building element as claimed in claim 1, wherein the blowing agent is formed of heptane.

15. An insulating timber frame building element as claimed in claim 1, wherein the blowing agent is formed at least in part of one or more of the following: water, carbon dioxide, bicarbonate of soda, titanium hydride or mixtures thereof.

16. An insulating timber frame building element as claimed in claim 1, wherein the blowing agent is formed at least in part of one or more of the following: light alcohols, ketones or ethers.

17. An insulating timber frame building element as claimed in any preceding claim, wherein the polymeric foam precursor is formed by mixing one or more monomeric components and the blowing agent.

18. An insulating timber frame building element as claimed in claim 17, wherein the monomeric component or components comprise one or more addition monomeric components.

19. An insulating timber frame building element as claimed in claim 17, wherein the monomeric components comprise condensation monomeric components.

20. An insulating timber frame building element as claimed in any of claims 1 to 16, wherein the polymeric foam precursor is formed by mixing polyol with the blowing agent and isocyanate.

21. An insulating timber frame building element as claimed in any of claims 1 to 16, wherein the polymeric foam precursor is formed by mixing polyol with the blowing agent and isocyanurate.

22. An insulating timber frame building element as claimed in claim 1, wherein the polymeric foam precursor is formed by mixing vinylic monomers.

23. An insulating timber frame building element as claimed in claim 1, wherein the polymeric foam precursor comprises plasticisers.

24. An insulating timber frame building element as claimed in claim 1, wherein the polymeric foam precursor is formed by mixing styrenic monomers.

25. An insulating timber frame building element as claimed in claim 1, wherein the polymeric foam precursor comprises a cross-linking or reticulating agent.

26. An insulating timber frame building element as claimed in 1, wherein the polymeric foam precursor comprises a catalyst or catalyst mixture to facilitate polymerisation and/or hardening of the polymeric foam precursor.

27. An insulating timber frame building element as claimed in claim 1, wherein the polymeric foam precursor comprises a flame-retardant agent.

28. An insulating timber frame building element as claimed in any preceding claim, comprising a plaster board operable to provide fire retardant properties to the timber frame building element.

29. An insulating timber frame building element as claimed in any preceding claim, being configured as a building element including one or more of the following: a wall, a roof, a ceiling, a floor and a partition member.

30. An insulating timber frame building element as claimed in any preceding claim, comprising openings defining apertures to accommodate windows, doors or other types of openings provided in a building element.

31. An insulating timber frame building element as claimed in any preceding claim, defining a plurality of cavities configured to receive a predetermined amount of polymeric foam precursor.

32. An insulating timber frame building element as claimed in any preceding claim, wherein the building element is planar.

33. An insulating timber frame building element as claimed in any preceding claim, wherein the building element is a panel.

34. An insulating timber frame building element as claimed in any preceding claim, wherein the building element is curved.

35. A method of producing an insulating timber frame building element, the method comprising the steps of: providing a timber frame element defining at least one cavity; providing a polymeric foam precursor comprising a blowing agent substantially comprising at least one compound selected from the group of n-pentane, iso-pentane and cyclo-pentane or a mixture thereof; introducing the polymeric foam precursor into the at least one cavity; expanding the polymeric foam precursor by the effect of volatilisation of the blowing agent while the polymeric foam precursor fills the at least one cavity and polymerises into a polymeric foam within the at least one cavity.

36. A method as claimed in claim 35, further comprising the step of flushing air in the at least one cavity with an inert gas prior to introducing the polymeric foam precursor within the cavity.

37. A method as claimed in claim 36, wherein the inert gas is nitrogen.

38. A method as claimed in claim 35, 36 or 37, further comprising the step of mixing the components of the polymeric foam precursor just before introducing the polymeric foam precursor into the at least one cavity.

39. A method as claimed in any of claims 35 to 38, comprising selecting and/or adjusting the pressure at which the polymeric foam precursor is introduced in the cavity.

40. A method as claimed in any of claims 35 to 39, comprising selecting and/or adjusting the rate at which the polymeric foam precursor is introduced in the cavity.

41. A method as claimed in any of claims 35 to 40, comprising selecting and/or adjusting the ratio of the components of the polymeric foam precursor.

42. A method as claimed in any of claims 35 to 41, comprising the step of mixing the hydrocarbon containing blowing agent with a component of the polymeric foam precursor before mixing it with the other components of the polymeric foam precursor.

43. An insulating timber frame building element defining at last one cavity and comprising a polymeric foam within the at least one cavity, the foam being formed within the at least one cavity from a polymeric foam precursor; wherein the polymeric foam precursor is expanded within the at least one cavity by a blowing agent substantially comprising at least one compound selected from the group of light non-halogenated liquid hydrocarbons or mixtures thereof.

44. An insulating timber frame building element defining at last one cavity and comprising a polymeric foam within the at least one cavity, the foam being formed within the at least one cavity from a polymeric foam precursor; wherein the polymeric foam precursor is expanded within the at least one cavity by a blowing agent substantially comprising at least one compound selected from the group of light saturated liquid hydrocarbons or mixtures thereof.

45. A method of producing an insulating timber frame building element, the method comprising: providing a timber frame element defining at least one cavity; providing a polymeric foam precursor comprising a blowing agent substantially comprising at least one compound selected from the group light non-halogenated liquid hydrocarbons or mixtures thereof; introducing the polymeric foam precursor into the at least one cavity; expanding the polymeric foam precursor by the effect of volatilisation of the blowing agent while the polymeric foam precursor fills the at least one cavity and polymerises into a polymeric foam within the at least one cavity.

46. A method of producing an insulating timber frame building element, the method comprising: providing a timber frame element defining at least one cavity; providing a polymeric foam precursor comprising a blowing agent substantially comprising at least one compound selected from the group of light saturated liquid hydrocarbons or mixtures thereof; introducing the polymeric foam precursor into the at least one cavity; expanding the polymeric foam precursor by the effect of volatilisation of the blowing agent while the polymeric foam precursor fills the at least one cavity and polymerises into a polymeric foam within the at least one cavity.