GB2467923A

GB2467923A - Timber-based insulating building section

Info

Publication number: GB2467923A
Application number: GB0902806A
Authority: GB
Inventors: Patrick Waterfield; David Maxwell
Original assignee: Maxwell & Waterfield Ltd; Tyrone Timberframes Ltd
Current assignee: Maxwell & Waterfield Ltd; Tyrone Timberframes Ltd
Priority date: 2009-02-20
Filing date: 2009-02-20
Publication date: 2010-08-25
Anticipated expiration: 2029-02-20
Also published as: GB2467923B; GB0902806D0; IE20100087A1

Abstract

A timber-based building section is constructed to have a U-value less than 0.25 W/m2K. It comprises a layer of natural or mineral fibre insulationh, a vapour control layergand an additional layer of insulation materiali. The natural or mineral fibre insulation layerhis specified as being 60mm or more thick and having a thermal conductivity between 0.044 and 0.025 W/mK. The additional insulation layeriis specified as being 50mm or more thick and having a thermal conductivity in the range 0.023 and 0.015 W/mK. The fibre insulationhmay comprise hemp fibre. The additional insulation layerimay be PIR, polyisocyanurate, or phenolic. Further layers of breather membranes, structural sheathing and insulation may be provided. The building section may be a wall section or panel, a roof section or panel. Buildings including the section and design systems involving the section are also provided.

Description

Timber-Based Building Section The present invention relates to a timber-based building section, in particular, a wall, roof or ceiling panel being part of a timber frame house, and use thereof in particular in a system for designing a timber frame building.

Timber frame houses and other dwellings are known in the art, and generally comprise a timber framework or skeleton in and around which the remaining parts of the walls, roofs and ceilings are applied. Timber frame houses can be faster to erect than traditional concrete block' based houses, as well as being more environmentally friendly and more easily able to accommodate different exterior and interior designs.

Thermal insulation in buildings such as domestic dwellings is an important factor to achieve thermal comfort for its occupants. Insulation reduces unwanted heat loss or gain, and can decrease the energy demands of heating and cooling systems.

The major feature of the thermal insulation of buildings is the thermal conductivity of the walls, ceilings and roof. Thermal conductivity is a property of a material that indicates its ability to conduct heat. In house building, it is defined as a "U-value", whose SI unit is W/m2.K. Each material that makes up a wall, roof or ceiling has a thermal conductivity measured in W/mK. The U-value provides an overall value and measurement taking into consideration the thickness and thermal conductivity of each material.

It is an object of the present invention to provide sections of a timber frame building having a reduced U-value to minimise or eliminate the requirement for central heating and the like.

According to one aspect of the present invention, there is provided a timber-based building section having a U-value less than 0.25, and comprising at least; (i) 60mm or more natural or mineral fibre insulation with a thermal conductivity between 0.044 and 0.025; (ii) a vapour control layer; and (iii) 50mm or more insulation material with a thermal conductivity in the range 0.023 and 0.015.

The building section may comprise a distinct construction element to be fitted between two or more structural timber frame elements.

Alternatively, the building section comprises a construction to be created in and/or around structural timber frame elements.

The structural timber frame elements may be any known timber posts, rafters, joists, etc., such as CLS (Canadian Lumber Standard) beams and posts, as well as for example, counter battens.

The vapour control layer provides diffusion for moisture and water so as to minimise condensation, whilst also providing air tightness. Preferably, the vapour control layer provides variable diffusion tightness in winter, and maximum diffusion openness in summer. A non-limiting example of a vapour control layer is the breathable membrane used in the Intello Air Tight System available from Proclima in Germany.

The vapour control layer is usually in the range 1 -2mm thick, and should assist in providing an overall air loss in a building using such a vapour control layer of below 1 m3/ph @50 pascals.

In one embodiment of the present invention, the U-value of the building section is less than 0.14 or less than 0.13.

The building section may comprise one or more further layers. Such further layers may be one or more of the group comprising: breather membranes or paper such as foil, structural sheathing such as OSB (Orientated Strand Board), plaster board, and one or more further layers of natural or mineral fibre insulation with a thermal conductivity between 0.044 and 0.025 and insulation material with a thermal conductivity in the range 0.023 and 0.015.

The natural or mineral fibre insulation may be any suitable material having the required thermal conductivity. Examples include natural materials such as hemp, and mineral fibre materials made by companies such as Moy, Knauf, etc, known in the art.

The insulation material may any suitable material having the required thermal conductivity, and may optionally be foil-backed. Examples include PIR (Polyisocyanurate), or phenolic.

In one embodiment of the present invention, the timber-based building section is a wall section at least comprising: (a) breather paper (foil); (b) OSB/other structural sheathing (between 9 and 25mm); (c) 140mm CLS 016/024 with 140mm natural or mineral fibre insulation with thermal conductivity between 0.044 and 0.025 thereinbetween; (d) airtight system (e) 50mm counter batten with 50mm natural or mineral fibre insulation with a thermal conductivity between 0.044 and 0.025 thereinbetween; (f) 50mm foil backed insulation with a thermal conductivity of 0.023 and 0.015; and (g) 12.5mm plasterboard.

In combination with outside render and blockwork, and with a cavity thereinbetween, there can be provided an external wall combination having a U-value of less than 0.13.

For a timber frame building, the timber structure is usually provided based on timber having a width or thickness of 120-180mm, such as 140- 160mm. The thickness of timber for internal walls is usually less, being in the range 80-120mm. Such thicknesses are sometimes referred to in the building trade as "6 inch" and "4 inch" walls.

In another embodiment of the present invention, the timber-based building section comprises a roof section comprising at least: (a) 60mm natural or mineral fibre insulation with a thermal conductivity between 0.044 and 0.025; (b) 100mm foil backed insulation with a thermal conductivity of 0.023 and 0.015; (c) 50mm foil backed insulation with a thermal conductivity of 0.023 and 0.015; (d) airtight system; (e) 50mm foil backed insulation with a thermal conductivity of 0.023 and 0.015; and (f) 12.5mm plasterboard.

Such a roof section would be located between rafters.

In combination with a tile or slate having a thermal conductivity of between 1.5 and 0.9, a ventilated air layer thereunder, a breathable roofing felt followed by a further ventilated air layer thereunder, there can be provided a roof panel combination can have a U-value of less than 0.12.

According to a third embodiment of the present invention, the timber-based building section is an external ceiling or collar tie comprising at least: (a) 100mm natural or mineral fibre insulation with a thermal conductivity between 0.044 and 0.025 on top of ceiling joist/collar ties and running perpendicular to collar ties/ceiling joists; (b) 200mm natural or mineral fibre insulation with a thermal conductivity between 0.044 and 0.025 between collar ties/ceiling joists; (c) airtight system; (d) 50mm foil backed insulation with a thermal conductivity of 0.023 and 0.015 across inside face of collar ties/ceiling joists; (e) 12.5mm plasterboard.

Such a section can have a U-value less than 0.12.

According to a second aspect of the present invention, there is provided a timber-based building having one or more timber-based building sections as herein defined, preferably wholly or substantially formed of timber-base building sections as herein defined, located in and/or around and/or between the structural timber frame or framework of the building.

Such a building may be a domestic house or other dwelling. Preferably, such a house comprises external walls, internal structural walls, ceilings and roofs including timber-based building sections as herein defined.

According to a further aspect of the present invention, there is provided a system for designing a timber-based building comprising at least: (a) one or more timber-based building sections as herein before defined; (b) an air tightness being less than 1 m3/ph @50 pascals; (c) a ventilation system with heat recovery; and (d) one or more windows having an average U-value of less than 1.5, preferably less than 1.1 or less than 1.0 or 0.9 or 0.8.

This system can preferably provide a timber-based building as described herein Ventilation systems with heat recovery are known in the art, and are designed to recover 80 to 90% of the heat that would normally be lost through natural ventilation in a concrete block house.

According to a fourth aspect of the present invention, there is provided a process for designing the heating of a timber-based building comprising at least one or more timber-based building sections as hereinbefore defined, the process comprising at least the steps of: performing U-value calculations on the walls of the timber-based building, preferably on each individual timber-based wall section taking into consideration the timber to insulation ratio and the ratio of window insulation; performing U-value calculations on the sloped/pitched roof and external ceiling/collar ties of the timber-based building, preferably on each individual timber-based sloped/pitched roof and external ceiling/collar ties section; calculating the air permeability rate; calculating the solar gains, including site specific solar gains, using historical met office data; and calculating any other internal heat gains.

The present invention encompasses all combinations of various embodiments or aspects of the invention described herein. It is understood that any and all embodiments of the present invention may be taken in conjunction with any other embodiment to described additional embodiments of the present invention. Furthermore, any elements of an embodiment may be combined with any and all other elements of any of the embodiments to describe additional embodiments.

Embodiments of the present invention will now be described by way of example only and with reference to the accompanying drawings in which: Figure 1 is a cross sectional view of an external wall comprising a first timber-based building section according to one embodiment of the present invention; Figure 2 is a cross sectional view of a roof comprising a second timber-based building section according to a second embodiment of the present invention; and Figure 3 is a cross sectional view of an external ceiling or collar tie comprising a third timber-based building section according to a third embodiment of the present invention.

Figure 1 shows an external wall cross section comprising ten layers (a-j), being a combination of boundary layers, defined thickness layers and at least one air cavity layer, extending between an outside render layer (a) and an internal plasterboard layer (j).

Layers (a) to (e) are known the art.

Layer (f) comprises a natural or mineral fibre insulation within the boundaries of 140mm CLS timber framework, being posts, beams, etc that form the skeleton of a timber-based building such as a timber framed house.

Similarly, layer (g) comprises natural mineral fibre insulation located within 50mm counter batten timber (or similar material) framework.

A vapour control layer is provided as layer (h) between layers (f) and (g), being an airtight system such as the Pro-Clima Intello material.

In practice, a timer framework is provided to create the timber skeleton of a new building such as a domestic house, and the building section shown in Figure 1 is constructed by the addition of the materials to locate layers (d) to (j) around the CLS timber framework, followed with the addition of the blockwork and render as layers (b) and (a), thus inherently creating the air cavity layer (c).

Once the external wall shown in Figure 1 is constructed, U-value calculations are carried out, taking into consideration the timber to insulation ratio, and the ratio of window to insulation throughout the building.

Figure 2 shows a sloped or pitched roof section, wherein its layers can be added between timber frame rafters, followed by the addition of a roofing felt and tiles or slates thereon, creating the air layers thereinbetween.

Once again, following construction of the complete roof section as shown in Figure 2, U-value calculations can be carried out.

Figure 3 shows an external ceiling or collar tie section locatable between ceiling joists or collar ties, generally to form a space such as a roof space thereabove.

Again, following construction of the external ceiling or collar tie sections shown in Figure 3, U-value calculations can be carried out.

Upon the complete construction of a building using one or more, usually a plurality, of the wall, roof and ceiling sections shown in Figures 1-3, the air permeability of the complete building can be measured. Along with calculations concerning solar gains through the windows, etc, as well as expected site specific solar gains using historical weather information, and information concerning any internal heat gains such as through a stove, cooker and the like, calculations can be carried out to determine the overall heat loss of the building, and then determine the actual heat requirement of the building.

The present invention is able to provide a building with sufficient heat insulation and ventilation such that central heating' generally based on an oil/wood! gas-fired boiler circulating water through a number of radiators, is not required to provide thermal comfort for its occupants.

Claims

Claims 1. A timber-based building section having a U-value less than 0.25, and comprising at least; (i) 60mm or more natural or mineral fibre insulation with a thermal conductivity between 0.044 and 0.025; (ii) a vapour control layer; and (iii) 50mm or more insulation material with a thermal conductivity in the range 0.023 and 0.015.
2. A building section as claimed in Claim I being a construction element to be fitted between two or more structural timber frame elements.
3. A building section as claimed in Claim I being a construction able to be created in and/or around structural timber frame elements.
4. A building section of any one of the preceding claims wherein the vapour control layer provides variable diffusion tightness in winter, and maximum diffusion openness in summer. * *** * S * S..

*:*::*
5. A building section as claimed in any one of the preceding claims wherein the vapour control layer is a breathable membrane used in the lntelloAirTightSystem.
6. A building section of any one of the preceding claims wherein the vapour control layer is in the range 1-2mm thick, and provides an overall air loss in a building of below I m3/ph @50 pascals.
7. A building section of any one of the preceding claims wherein the U-value of the building section is less than 0.14 or less than 0.13.
8. A building section of any one of the preceding claims comprising one or more further layers being one or more of the group comprising: breather membranes or paper such as foil, structural sheathing such as OSB (Orientated Strand Board), plaster board, and one or more further layers of (a) natural or mineral fibre insulation with a thermal conductivity between 0.044 and 0.025, and (b) insulation material with a thermal conductivity in the range 0.023 and 0.015.
9. A building section of any one of the preceding claims wherein the natural or mineral fibre insulation is hemp and/or mineral fibre materials.
10. A building section of any one of the preceding claims wherein the insulation material is PIR (Polyisocyanurate) or phenolic.
11. A building section of any one of the preceding claims being a wall section at least comprising: *.. : 20 * *** (a) breather paper (foil); *:::* (b) OSB/other structural sheathing (between 9 and 25mm); (c) 140mm CLS C16/C24 with 140mm natural or mineral fibre insulation with thermal conductivity between 0.044 and 0.025 thereinbetween; (d) airtight system (e) 50mm counter batten with 50mm natural or mineral fibre insulation with a thermal conductivity between 0.044 and 0.025 thereinbetween; (f) 50mm foil backed insulation with a thermal conductivity of 0.023 and 0.015; and (g) 12.5mm plasterboard.
12. An external wall combination for a timber frame building having a U-value of less than 0.13 comprising the building section as defined in claim 11 in combination with outside render and blockwork, with a cavity thereinbetween.
13. A building section of any one of claims I to 10 being a roof section comprising at least: (a) 60mm natural or mineral fibre insulation with a thermal conductivity between 0.044 and 0.025; (b) 100mm foil backed insulation with a thermal conductivity of 0.023 and 0.015; (c) 50mm foil backed insulation with a thermal conductivity of 0.023 and 0.015; (d) airtight system; (e) 50mm foil backed insulation with a thermal conductivity of 0.023 and 0.015; and (f) 12.5mm plasterboard. * S S * 20 * .5.
14. A roof panel combination having a U-value of less than 0.12 *:*::* comprising the building section as defined in claim 13 in combination with a tile or slate having a thermal conductivity of between 1.5 and 0.9, a ventilated air layer thereunder, a breathable roofing felt followed by a further ventilated air layer thereunder. * I
15. A building section of any one of claims I to 10 being an external ceiling or collar tie comprising at least: (a) 100mm natural or mineral fibre insulation with a thermal conductivity between 0.044 and 0.025 on top of ceiling joist/collar ties and running perpendicular to collar ties/ceiling joists; (b) 200mm natural or mineral fibre insulation with a thermal conductivity between 0.044 and 0.025 between collar tieslceiling joists; (c) airtight system; (d) 50mm foil backed insulation with a thermal conductivity of 0.023 and 0.015 across inside face of collar ties/ceiling joists; (e) 12.5mm plasterboard.
16. A building section of claim 15 having a U-value less than 0.12.
17. A timber-based building having one or more timber-based building sections as defined in any one of claims ito 11, 13, 15 or 16 located in and/or around and/or between the structural timber frame or framework of the building.
18. A building as claimed in claim 17 being a domestic house or other dwelling, preferably a house comprising external walls, internal structural 20 walls, ceilings and roof(s). *,.. *-.
19. A system for designing a timber-based building comprising at least: (a) one or more timber-based building sections as defined in any one of : i.,. 25 claims Ito Ii, 13, 15or16; (b) an air tightness being less than 1 m3lph @50 pascals; (c) a ventilation system with heat recovery; and (d) one or more windows having an average U-value of less than 1.5, preferably less than 1.1 or less than 1.0 or 0.9 or 0.8.
20. Use of the system as claimed in claim 19 to provide a timber-based building as claimed in claim 17 or claim 18.
21. A process for designing the heating of a timber-based building comprising at least one or more timber-based building sections as defined in any one of claims 1 to 11, 13, 15 or 16, the process comprising at least the steps of: performing U-value calculations on the walls of the timber-based building, preferably on each individual timber-based wall section taking into consideration the timber to insulation ratio and the ratio of window insulation; performing U-value calculations on the sloped/pitched roof(s) and external ceiling/collar ties of the timber-based building, preferably on each individual timber-based sloped/pitched roof and external ceiling/collar ties section; calculating the air permeability rate; calculating the solar gains, including site specific solar gains, using historical met office data and ::::b: 20 calculating any other internal heat gains.
22. A timber-based building section substantially as hereindefined and with reference to the accompanying drawings.III SalSI.e...S