WO2008149090A1

WO2008149090A1 - Thermal insulation structure

Info

Publication number: WO2008149090A1
Application number: PCT/GB2008/001909
Authority: WO
Inventors: John Payne; Leslie James Squires
Original assignee: Hunt Technology Limited
Priority date: 2007-06-04
Filing date: 2008-06-04
Publication date: 2008-12-11
Also published as: GB0710632D0; GB2449985A; GB2449985B; GB0810212D0

Abstract

A thermal insulation structure (1) for use in buildings includes an insulating body (1a) incorporating flexible insulating material (1b) enclosed between outer layers (2) and (3) extending beyond the flexible insulating material (1b) to form two flaps (9) extending from opposite sides respectively of the insulating body for positioning and securing the insulation structure to adjacent supporting members (6), such as rafters, wall studs or floor joists, within the building, the insulating body (1a) being capable of being fitted in a space between the adjacent supporting members (6). Also included is a method of insulating a building using a thermal insulation structure (1) and a building whenever insulated by such a thermal insulation structure (1) and method.

Description

Thermal Insulation Structure

The invention relates to a thermal insulation structure for use in buildings and a method of insulating buildings, more particularly but not exclusively applicable to wooden or steel framed structures such as roofs made from rafters and walls with timber studs or floors with joists.

A common method of constructing buildings or elements of buildings is to create a supporting frame of steel or timber. For example, a pitched roof is constructed of rafters which meet at the apex of the roof providing a support for tiles on the exterior. A floor or ceiling may be built from wooden joists and a wall from wooden studs or steel beams. The invention relates to insulation fitted between such supporting members. Alternatively, the structural integrity of a wall may be provided by a solid masonry, stone or timber wall, with a framework of timber studs fitted inside. The invention also relates to insulation fitted between such a framework of non-supporting members

Concerns about the impact of carbon dioxide emissions on climate change have led to pressure on designers and constructors of buildings to reduce the level of carbon dioxide emitted from a building. This is addressed both by improving the efficiency of heating systems therein, and also by reducing heat losses from the building.

Heat is lost from the building in two ways - through the fabric of the building via conduction, convection and radiation, and also by loss of warm air which is replaced by cold air. Both of these need to be addressed to produce an energy efficient building.

To reduce the amount of heat lost through the fabric of the building, the space between the supporting members is commonly used for insulation. Conventional insulation materials such as rigid polyurethane boards (PUR) and glass or mineral wool are widely used in this way. However, neither of these methods of insulation can effectively prevent leakage of warm air from the building to the outside, which is replaced with colder air that requires energy to heat.

Rafters in buildings are typically made of softwood, with dimensions of width 38 or 50mm, depth from 75 to 200mm and spaced at 400 or 600mm centres. The softwood is never cut to the exact size, and the specification generally includes a tolerance of + or - 1 , 1.5 or even 2mm. The dimensions of the softwood typically change on becoming wet, drying out or ageing, leading to warping, twisting, bowing or spring. Such wood is rarely straight when it comes to be used. The rafter spacing is therefore not even, the sides of the rafter spaces are not straight and may fluctuate. As the timber ages, further warping occurs leading to slight movement of the rafters or joists relative to each other, and changing the width and shape of the spaces in between.

The spacing of 100 x 38mm rafters at a nominal spacing of 400mm centres in a residential house was measured as follows:

The space between the rafters varies from +34 to -31 , equivalent to + or - 9% of the nominal width.

Rigid PUR boards need to be accurately measured, marked out and cut to fit each individual rafter space. Since rafter spaces are not even it is impossible in practice to obtain a close fit of the PUR board between the rafters, even for a skilled worker. Thicker PUR boards are even more difficult to cut and fit accurately. Gaps between the edge of the board and the rafter allow air to leak from the inside of the rafter space to the outside. Over time, the rafters age and distort, making the gaps larger and increasing air leakage.

Glass wool is an air open material, allowing passage of warm air through the wool from the inside of the rafter space to the outside. Glass wool is not able to prevent air leakage. Increasing the thickness of the glass wool does not provide an answer since convection cells can form in layers of glass wool greater than 25mm in depth, whereby an air current circulates warm air from the inside of the rafters to the outside and cold air in the opposite direction. Increasing the density of the glass wool to form a batt or board does not provide a complete solution since air is still able to circulate through the body of the glass wool. In use and over time, loose materials such as glass wool can slump down inside a wall or roof cavity, leaving a gap at the top with little or no insulation material.

In addition, both PUR and glass wool are time-consuming and unpleasant materials to use. Sawing of PUR boards generates large quantities of PUR dust and "crumbs", which cause a very messy environment. The crumbs stick by electrostatic attraction to clothing and hair, making protective clothing desirable. Glass wool requires personal protective equipment such as a face mask to prevent inhalation of small glass particles and gloves to prevent a rash on areas of skin that come into contact with glass wool. Multi-foil insulation materials provide a barrier to air leakage and air permeation, and provide extremely effective insulation performance by generating air spaces with low emissivity surfaces. However, in order to generate these spaces, the multi-foil must be battened above or below the rafters. This is a time consuming process, and in addition compresses the multi-foil leading to a loss of performance at the battened areas and the introduction of cold bridges into the roof or wall structure. These materials are not generally proposed for use between rafters, although they may intrude a short distance into the space.

Air spaces are an important component of many roof structures. Ventilated air layers allow the removal of water vapour from the roof structure, preventing condensation of water inside the roof, which might lead to rotting of timbers, leakage into the room below, or reducing the thermal performance of insulation material. Unventilated air layers can make significant contributions to insulating a roof or wall structure. Still air has very low thermal conductivity. If the still air is surrounded by low emissivity surfaces the thermal resistance of the air space is increased.

In some roof structures it is a building requirement to provide a ventilated air space. For example where a roof has a non-breathable roofing membrane fitted above rafters, a ventilated 50mm air space must be maintained below the roofing felt between the rafters. Insulation that is fitted between rafters must not obstruct this air space or compromise the ventilation of the roof structure.

The main object of the present invention to overcome, or at least substantially overcome, all of these problems, by providing an insulation material that fits between rafters, is easy and quick to install, incorporates highly thermally efficient air layers into the roof, wall or floor structure, prevents air leakage even with uneven or warped rafters and does not require battening. From one aspect, the present invention resides in a thermal insulation structure for use in buildings, the structure comprising an insulating body comprising flexible insulating material and two flaps extending from opposite sides respectively of the insulating body for positioning and securing the insulation structure to adjacent supporting members within the building, wherein the insulating body is capable of being fitted in a space between adjacent supporting members with sufficient drape to compensate for variation in distance between the supporting members such that, in use, airspace adjacent the structure is substantially preserved.

By means of the invention, the insulation structure can be fitted rapidly and cleanly without the need for specialist skills, personal protective equipment and with minimal wastage. Moreover, stable and unobstructed air layers are formed above, below, or above and below the insulation structure and air layers are a very efficient insulating medium.

In order to compensate for variations in the width of the space between the supporting members and provide continuous insulation across the whole of the supporting member space without any gaps that would allow air leakage, the insulation may be constructed slightly wider than the space to be insulated allowing some drape.

Ideally, in such structures, the inner insulating body has a thickness which is greater than that of the outer side flaps.

The length of the side flaps may be varied to suit the particular supporting member space but to ensure sealing of any adjacent air space, the flaps have a length that is sufficient to wrap them around two surfaces of the supporting members. Thus, in the case of rectangular, in cross section supporting members such as roof rafters, wall studs or floor joists, the flaps are wrapped around the oppositely facing side surfaces of the supporting members and around the upper, or lower or upper and lower surfaces of the side member where they are secured by any appropriate means such as staples, nails, tape, screws or glue, for example.

For ease and simplicity of construction, the flexible insulating material of the insulating body is conveniently enclosed between outer layers which are sealed along the edges of the insulating material and which extend beyond the sealed body to form the side flaps.

Of course, the side flaps extend for the full width of the supporting body to ensure sealing of any adjacent air space.

The invention also comprehends methods of insulating a building using any of the insulating structures defined hereinabove as well as a building insulated with the insulating structures and by the methods.

Expressed in another way and from another aspect, the invention resides a method of insulating a building, the method comprising fitting a thermal insulating structure having two flaps, between two adjacent supporting members of the building and securing the flaps to ends of the supporting members thereby positioning the insulating structure such that airspace adjacent the structure is substantially preserved.

In order that the invention may be more readily understood, reference will now be made, by way of example only, to the accompanying drawings in which:

Figure 1 shows a thermal insulation structure in accordance one embodiment of the invention;

Figure 2 shows a thermal insulation structure in accordance with another embodiment of the invention; Figure 3 shows a thermal insulation structure in accordance with a further embodiment of the invention;

Figure 4 shows a thermal insulation structure in accordance with a still further embodiment of the invention;

Figure 5 illustrates the relative dimensions of the thermal insulation structure of Figure 1 as they correspond to the dimensions of supporting members of a building;

Figure 6 shows thermal insulation structures fitted between supporting members of a building according to another embodiment of the invention;

Figure 7 shows two thermal insulation structures fitted in between supporting members of a building according to a further embodiment of the invention;

Figure 8 shows two thermal insulation structures fitted in an alternative way between supporting members of a building according to yet another embodiment of the invention;

Figure 9 shows thermal insulation structures of Figure 6 with an additional insulation layer fitted under the supporting members;

Figure 10 shows a thermal insulation structure according to another embodiment of the invention, the structure being fitted between supporting members of a building; and

Figure 11 shows the thermal insulation structure of Figure 10, with a rigid further insulation material. In the drawings, the same reference characters are used to designate the same or similar parts.

As can be seen in Figures 1 and 2, a thermal insulation structure, generally indicated at 1 has an insulating body 1a incorporating a single layer of flexible insulating material 1 b and adapted to be fitted between supporting members in the form of rafters (not shown). The insulating body 1 has a width slightly greater than the nominal rafter space width, typically 400 or 600mm and a thickness less than the rafter depth and includes outer layers 2 and 3 which enclose the flexible insulating material 1a and are sealed along the bottom, as illustrated, side edges of the insulating material 1a and insulating body 1 , as indicated at 4 in Figure 1 or midway of the width of the insulating material 1a and insulating body 1 , as indicated at 4 in Figure 2. The outer layers 2 and 3 extend beyond opposite sides respectively of the insulating body 1 to form side flaps 9 extending from these opposite sides and which can be wrapped inside and around ends/edges of adjacent rafters to position the insulating structure between the adjacent rafters within the building and then be fixed in place. The dimension of 400 or 600mm is a common spacing for rafters, joists and wall studs between which the insulating body 1 can be laid.

The insulating material 1a can be any material that is flexible, can be compressed and subsequently recover to its original thickness and most importantly has a low thermal conductivity. Suitable materials include glass or mineral wool, sheeps' wool, paper balls or shredded paper, balls of materials suitable for insulation other than paper such as polystyrene, flexible open-cell or closed-cell foam, e.g. polyethylene or polystyrene foam, nonwoven wadding, 3- dimensional spacer fabrics, fleece or bubble wrap. The preferred materials are flexible foams and non-woven waddings, especially non-woven polyester wadding. The insulation structure 1 can also contain other components such as woven or non-woven fabrics, metallised foils, films or other spacers such as 3-dimensional knitted fabrics or corrugated materials. Moreover, the insulation structure 1 can contain multiple layers of any of these components, of course, including those referred to above for the flexible insulating material, which may be either interleaved with other components, or have two or more of the same component adjacent to each other. The number, nature and thickness of these layers may vary according to the particular application for which the insulation structure is intended. The minimum number of layers is three; two outer layers and one inner layer of material of low thermal conductivity. The thickness of each inner layer of material of low thermal conductivity may also vary, from 1mm up to a maximum of 30mm. Preferably each inner layer will be between 2 and 20mm and even more preferably between 5 and 15mm.

Inner separating films acting as spacers can be water vapour permeable or impermeable. Moisture vapour permeable films include microporous polypropylene, polyurethane, polyester and polyethylene, and regenerated cellulose films such as Cellophane™ marketed by Innovia Films Ltd.. Moisture vapour impermeable films include cast, extruded or blown polypropylene, polyethylene, polyester. Films may be perforated to allow passage of water vapour. The films could be attached only at the edges of the product (i.e. in the flaps) or glued to the adjacent flexible insulating material 1b in the insulating body 1a of the insulating structure 1.

The two outer layers 2 and 3 can be any material that is flexible yet strong enough to be fixed to the rafter edges/side surfaces/ends, such as woven or nonwoven fabric, paper or laminated structures. The outer layers 2 and 3 can optionally have a low emissivity surface formed by metallization of the outer surface of the upper and lower layers. Such metal would typically be aluminium. The aluminium surface may be protected from corrosion or physical damage by a thin coating of a suitable protective material, such as polypropylene, or a water or solvent based lacquer such as acetate, acrylic or nitrocellulose.

So, the multiple layers of flexible insulating material can be of the same material or combinations of two or more of the materials mentioned above.

The insulation structure 1 shown in Figure 3 differs from the embodiments of Figures 1 and 2 in having three layers of flexible insulating material 1b interleaved with two intermediate layers 5 and which act as spacers. In Figure 3 the interleaved intermediate layers 5 simply extend to the edge of the insulating structure without being bonded or sealed. On the other hand, the embodiment of Figure 4 has two layers of flexible insulating material 1b interleaved with one intermediate layer 5 which is sealed to the upper and lower layers by the seal 4 and extends between the upper and lower layers 2, 3 beyond the seal 4 where the intermediate layer 5 is incorporated in the flaps 9.

Since the insulating material is slightly wider than the rafter spacing, it will drape slightly inside the space. This drape allows it to accommodate variations in rafter space due to distortion of timbers. Where the rafter spacing is less than the nominal width, the insulation material will drape slightly more, but will still form a continuous layer of insulation across the whole space. Where the rafter spacing is greater than the nominal width, the insulation material will drape slightly less, but will again form a continuous layer of insulation across the whole rafter space which is the situation to be explained with reference to Figure 5.

Referring now to Figure 5, if the spacing between the supporting members constituted by the rafters 6 has a nominal width Rmm, then to accommodate variations in the rafter spacing, the width of the insulating body 1a should be 1.10 x Rmm as shown in Figure 5. If it is any greater than this, the centre of the insulation material will droop down below the bottom edge of the rafters and will not preserve an air space. If the rafter depth is Dmm and rafter width is Wmm, then the flaps should each be D/2 + W mm in width.

The invention will now be further explained with reference to the following examples.

EXAMPLE 1. Where the rafters are 100mm deep and 50mm wide and spaced at 400mm centres, then the rafter space is nominally 350mm. To fit this rafter space, the width of the insulating material should be up to 10% greater than 350mm. To accommodate variations in rafter spacing due to distortion of timbers, the width of insulating material should be 355 - 400mm, preferably 360 - 390mm and even more preferably 370 - 380mm. The width of the flaps should be 100/2 + 50 = 100mm.

EXAMPLE 2. Where the rafters are 100mm wide and 38mm wide and spaced at 400mm centres, then the rafter space is nominally 362mm. To fit this rafter space, the width of the insulating material should be 10% greater than 362mm. To accommodate variations in rafter spacing due to distortion of timbers, the width of insulating material should be 365 - 420mm, preferably 370 - 415mm and even more preferably 380 - 410mm. The width of the flaps should be 100/2 + 38 = 138mm.

EXAMPLE 3. Where the rafters are 150mm deep and 50mm wide and spaced at 600mm centres, then the rafter space is nominally 550mm. To fit this rafter space, the width of the insulating material should be 10% greater than 550mm.

To accommodate variations in rafter spacing due to distortion of timbers, the width of insulating material should be 570 - 630mm, preferably 580 - 620mm and even more preferably 600 - 610mm. The width of the flaps should be 150/2 + 50 = 125mm. The thickness of the flexible insulation material 1b can be from 20 to 150mm, preferably 25 to 100mm and even more preferably from 30 to 60mm. For example, a common rafter depth is 100mm. In this case, where a non-breathable roofing felt is installed, an ideal thickness of the insulating body 1a is 30mm. This allows a 50mm ventilated air layer above the insulation and a 20mm unventilated air layer below. Where a breathable roofing felt is installed, an ideal thickness of the insulating structure is 60mm. This allows a 20mm unventilated air layer above the insulation and a 20mm unventilated air layer below.

Another common rafter depth is 75mm. Where a breathable roofing felt is installed, an ideal thickness of the insulating structure is 35mm. This allows a 20mm unventilated air layer above the insulation and a 20mm unventilated air layer below. Where a non-breathable roofing felt is installed, an ideal thickness of the insulating structure is 30mm. This allows a 50mm ventilated air layer above the insulation and a 20mm unventilated air layer below if the rafters are battened out by a further 25mm in depth.

Yet another common rafter depth is 150mm. Where a breathable roofing felt is installed, an ideal thickness of the insulating structure is 37.5mm. This allows a 25mm unventilated air layer above the insulation, one thickness of insulation, a further 25mm unventilated air layer, a second layer of insulation and a 20mm unventilated air layer below.

The width of the flaps 9 along the side of the insulating body 1 should be sufficient to run along the oppositely facing edges/side surfaces of the rafters 6 and over the edges of the rafters 6 to allow fixing, as can be appreciated from

Figure 6 which shows how the invention is used between the rafters 6. The insulating body 1 is situated between the rafters 6 and the side flaps 9 run along the side surfaces and across the top surfaces of the rafters, 6 and are fixed in place by suitable fixings 8. Suitable fixing methods include nailing, stapling, screwing, gluing and taping. The overlap of the flaps 9 indicated at 9a gives a continuous line of the outer layers 2, 3, ensuring airtightness. A further fixing (not shown) is placed to attach the inner edges of the side flaps 9 to the opposing side surfaces of the rafters 6.

The side flaps 9 can be marked to allow the installer to line up with the edge of the rafter so that the insulation is always a pre-determined depth within the rafter.

A common rafter size is 100 x 50mm. In this case the width of the flap should be 50mm to run along the edge of the rafter from the centre to the bottom edge, then a further 50mm over the edge of the rafter to allow fixing, or a total width of 100mm.

Other preferred widths of side flaps 9 for different size rafters 6 are from 50mm to 150mm.

The two outer layers 2 and 3 are sealed along the opposite edges of the insulating body 1a to create an enclosed volume within which the flexible insulating material 1b is located, of well defined width and depth. The insulating body 1 can be any suitable length. It is preferred that the insulating structure 1 be made in a long roll, allowing a length equal to the rafter length to be cut off and fitted. This process allows the whole rafter length to be insulated with a single piece of material, and eliminates the need for overlapping or joining of pieces of insulation structure 1. Joints of insulation material generally have to be sealed, for example with adhesive tape. This is a time-consuming and expensive process. Poor joints can lead to a reduction in performance if there is not a continuous layer of insulation material. Over the lifetime of a roof, tapes may fail, and the joints are no longer secure. Tapes cannot be relied upon to give long term airtightness in a roof structure. The method of sealing the two outer layers 2 and 3 can include sewing, gluing (adhesive bonding), or thermal bonding (welding) using a thermo-bonding calendar or ultrasound.

The inside of the insulation structure 1 preferably contains multiple layers of reflective foils and insulating material of low thermal conductivity value.

The insulation structure 1 can be installed between rafters, wall studs or joists from either the underside or the top of the rafters or joists, or inside or outside of the wall studs. Access to both sides of the rafters, wall studs or joists is not required.

Thus, Figures 7 and 8 show variations of fitting two insulation structures 1 having insulating bodies 1a installed within a single rafter space between adjacent rafters 6. In Figure 7 the two insulation structures 1 are fitted from the same side of the single rafter space whereas in Figure 8 the two insulation structures 1 are fitted from opposite sides of the single rafter space.

Fixing the insulation structure 1 in the centre of the rafter space generates an air space on either side of the material. The space above the material can be either ventilated or non-ventilated. A ventilated air space of 50mm depth will allow water or water vapour to leave the roof space • and prevent build-up of condensation. An unventilated air space will add to the thermal performance of the roof structure.

It is well known that air layers form effective insulation barriers to the loss of heat by conduction, and indeed air spaces are an important component of many insulated structures such as walls and roofs. However large air gaps are susceptible to heat transfer by convection as air currents are established, drawing warm air from one side of the air gap to the other. Air trapped in small layers where convection is inhibited forms the basis of many conventional insulation materials such as textile constructions, bubble films, mineral wool and foam boards or panels.

Dry air has a very low thermal conductivity value of 0.025 W/mK. Most solid materials have higher conductivities than this. Traditional insulating materials such as mineral wool, polyurethane foam or polystyrene function by trapping air or other gas inside a low density solid. These systems generally have a thermal conductivity higher than that of dry air since the solid material allows conduction of heat through the structure. They are therefore less effective insulators than a perfect air barrier. In addition, these materials will allow heat transfer by radiation.

More recent insulating systems seek to reduce radiation heat losses by incorporating into their structure a reflective barrier.

It is also known that the thermal resistance of an airspace is increased when the surfaces bordering that space have a low emissivity. The thermal resistance is particularly increased when both surfaces are of low emissivity - one surface will reflect any incident radiation, whilst the opposing surface will absorb very little incident radiation.

The optimum insulation properties for a non-ventilated airspace can be calculated using known equations - these are described in BS EN ISO 6946:1996 as follows:

The thermal resistance of an airspace Rg is given by:

Rg = 1 / ( h_a + h_r)

where h_a is the conduction/convection coefficient and h_r is the radiation coefficient For heat flow upwards, as would be encountered in a roof system, h_a is calculated as the larger of either 1.95 W/m²K or 0.025/d where d is the thickness of the airspace in the heat flow direction. The value of h_a for different thickness air spaces is therefore:

Hr is given by h_r= Eh_ro

Where E is the intersurface emittance hrø is the radiative coefficient for a black body surface. At 1O⁰C, h_ra = 0.51

And E = 1 / (1/e1 + 1/e2 -1)

Where e1 and e2 are the hemispherical emissivities of the surfaces bounding the airspace.

The thermal resistance of 20mm airspaces in m²K/W are shown:

The table shows clearly the effect of the emissivity of the two surfaces. In particular, changing from one to two low emissivity boundaries increases the thermal resistance from 0.45 to 0.55 m²K/W, an increase of 22%.

Moving to an extremely low emissivity surface of 0.05 does not produce a significant improvement. The difficulty of achieving and maintaining such a surface are not justified by the slight increase in R.

The optimum emissivity of the outer layers is in the range 0.05 to 0.4, preferably 0.05 to 0.2 and even more preferably 0.05 to 0.1.

Embodiments of the present invention can be used in conjunction with conventional insulation materials to generate a hybrid system. For example, an insulation structure according to the present invention can be fitted between rafters and PUR boards fitted above or below the rafters. A foil-backed or standard plasterboard can be fitted below the rafters, and may also be used to generate an air layer.

Fig 9 shows a roof structure consisting of a breathable roofing membrane 10 fitted above rafters 6 and a plurality of insulation structures 1 like those of Figure

1 having a single layer of flexible material 1b and fitted between adjacent rafters

6 to form an unventilated air space 11 between the roof membrane 10 and the rafters 6. A continuous sheet of insulation 12 is fixed below the rafters 6, forming another unventilated air space 13. Suitable sheets of insulation include rigid polyurethane, PUR, phenolic foam, polystyrene foam, or a multi-foil insulation material. If the sheet is faced with a low emissivity surface such as aluminium foil, the air space 13 has a particularly high thermal resistance.

In a modification of the roof structure of Fig. 9, the roof membrane 10 is not breathable and the air space 11 between the thermal insulating structures 1 and the non-breathable roof membrane is ventilated. A further way to install an insulation structure 1, like that of Figure 3 for example, between adjacent rafters 6 is shown in Fig 10. The flaps 9 are fixed to, and around, the ends/edges of the rafters 6 as previously described and additional fixings 14 are applied to the flaps 9 and into the sides of the rafters 6 near the insulating body 1a. However, in this case, the insulating body 1a has a width which is significantly greater than that of the rafter space and is folded along both sides to form side portions 17 adjacent the flaps 9. The side portions 17 are run along the inside surfaces of the rafters 6 inside the rafter space, as shown. Further fixings 14a are applied through the side portions 17 of the insulating body 1a and flexible insulation material 1 b and into the oppositely facing sides of the rafters 6. When fixed in this way, there are layers of flexible insulation material 1b running up the oppositely facing sides of the rafters 6.

The flexible insulation layers 1b of the side portions 17 can be used to accommodate a rigid insulation material 15 in the form of a board, shown in Fig 11 to which reference will now be made. The flexible insulation material 1b of the side portions 17 is compressed by the rigid insulation material 15 as indicated at 18 forming a tight seal with the rigid insulation material 15. This arrangement allows rigid insulation products to be fitted between rafters and yet maintain a tight fit. Further, such an arrangement allows the use of rigid insulation materials without the requirement for precise measuring, marking and fitting, since the flexible insulation material 1b can compress to accommodate the rigid material 15 which reduces the skill required to fit the rigid insulation material 15 and also the time needed.

In this embodiment, the width of the flexible insulation material is not limited to a distance of 110% of the rafter space but can be greater, to allow enough material to wrap inside the rafters. Insulation structures according to the invention may be manufactured in the form of a long continuous roll and supplied either in long roll form or as pre-cut lengths. The side flaps 9 may be folded over when rolled, and are unfolded prior to use.

Various modifications may be made to the embodiments of the invention described herein without departing from the scope of the invention as defined in the appended claims.

Claims

1. A thermal insulation structure for use in buildings, the structure including: an insulating body incorporating flexible insulating material; and two flaps extending from opposite sides respectively of the insulating body for positioning and securing the insulation structure to adjacent supporting members within the building, the insulating body being capable of being fitted in a space between the adjacent supporting members with sufficient drape to compensate for variations in the width of the space between the supporting members such that, in use, air space adjacent the insulation structure is at least substantially preserved.

2. A thermal insulation structure according to Claim 1 , wherein the insulation body further incorporates two outer layers enclosing the flexible insulating material, the upper and lower layers extending beyond the flexible insulating material to form the flaps.

3. A thermal insulation structure according to Claim 1 or Claim 2, wherein the two flaps, in use, extend for the width of the supporting members to seal any adjacent air space.

4. A thermal insulation structure according to any of Claims 1 to 3, wherein the two flaps, in use, have sufficient length to run along, and over, an edge of the respective supporting member to allow fixing of the flaps to the respective supporting members.

5. A thermal insulation structure according to Claim 4, wherein the length of the two flaps, in use, is sufficient to wrap around two surfaces of the respective supporting members.

6. A thermal insulation structure according to any of Claims 1 to 5, wherein the two flaps, in use, each have a length approximately equal to half the depth plus the width of the respective supporting member.

7. A thermal insulation structure according to any of Claims 1 to 6, wherein the two flaps are marked to line up with edges of the supporting members such that, in use, the insulation structure is positioned at a pre-determined depth within said space.

8. A thermal insulation structure according to any of Claims 1 to 7, wherein the flexible insulating material adjacent the flaps, in use, runs up respective edges of the supporting members and is fixed thereto.

9. A thermal insulation structure according to any of Claims 1 to 7, wherein the insulating body, in use, has a width that is slightly wider than the width of said space.

10. A thermal insulation structure according to any of Claims 1 to 7, wherein the insulating body, in use, has a width that is 10% greater than the width of said space.

11. A thermal insulation structure according to any preceding claim, wherein said space includes at least one unobstructed air layer.

12. A thermal insulation structure according to Claim 11 , wherein the at least one unobstructed air layer is located below the insulation structure, in use.

13. A thermal insulation structure according to Claim 11 , wherein two unobstructed air layers are formed, one above and one below the insulation structure, in use.

14. A thermal insulation structure according to any of Claims 11 to 13, wherein at least one said unobstructed air layer is unventilated.

15. A thermal insulation structure according to Claim 8, or any claim dependent thereon, and further including a rigid insulating material for extending between and compressing the flexible insulating material adjacent the flaps and being in spaced apart relationship with the insulating body, in use.

16. A thermal insulation structure according to any preceding claim, and including at least one layer of the flexible insulating material.

17. A thermal insulation structure according to Claim 16, and including two or more layers of the flexible insulating material.

18. A thermal insulation structure according to Claim 16 or Claim 17, wherein the or each layer of the flexible insulating material has a thickness in the range of 1mm to 30mm.

19. A thermal insulation structure according to Claim 16 or Claim 17, wherein the or each layer of the flexible insulating material has a thickness in the range of

2mm to 20mm.

20. A thermal insulation structure according to Claim 16 or Claim 17, wherein the or each layer of the flexible insulating material has a thickness in the range of 5mm to 15mm.

21. A thermal insulation structure according to any preceding claim, wherein the flexible insulating material can be compressed and subsequently recover to its original thickness and is of low thermal conductivity.

22. A thermal insulation structure according to any preceding claim, wherein the flexible insulating material includes at least one of glass or mineral wool, sheep's wool, paper balls or shredded paper, flexible open cell or closed-cell foam, non-woven wadding, three-dimensional spacer fabrics, fleece or bubble wrap, flexible foams, or non-woven polyester wadding.

23. A thermal insulation structure according to claim 22, wherein the foam is of polyethylene or polystyrene.

24. A modification of the thermal insulation structure according to claim 22 or claim 23, wherein the balls are of an insulating material other than paper.

25. A thermal insulation structure according to claim 24, wherein the other insulating material is polystyrene.

26. A thermal insulation structure according to Claim 17 or any claim dependent thereon, wherein the insulating body further includes one or more spacers for the layers of flexible insulating material and selected from at least one of woven or non-woven fabrics, metallised foils, films, three-dimensional knitted fabrics or corrugated materials.

27. A thermal insulation structure according to Claim 26, wherein the or each spacer is a film that separates the layers of the flexible insulating material.

28. A thermal insulation structure according to Claim 27, wherein the or each film is attached along the edges of the product in the two flaps or attached to the adjacent flexible insulating material in the insulating body.

29. A thermal insulation structure according to Claim 28, wherein the or each film is water vapour permeable or impermeable.

30. A thermal insulation structure according to Claim 17 or any claim dependent thereon wherein the insulating body contains multiple layers of reflective foils and said flexible insulating material.

31. A thermal insulation structure according to Claim 2 or any claim dependent thereon, wherein the outer layers of the insulation body are of woven or non- woven fabric, paper or are laminated structures.

32. A thermal insulation structure according to Claim 2 or any claim dependent thereon, wherein the upper and lower layers of the insulation body have a low emissivity surface formed by metallization of the upper and lower layers.

33. A thermal insulation structure according to Claim 32, wherein the metal is aluminium.

34. A thermal insulation structure according to Claim 32, wherein the aluminium low emissivity surface is coated with a protective material.

35. A thermal insulation structure according to Claim 2 or any claim dependent thereon, wherein the outer layers of the insulating body are sealed along the opposite side edges respectively of the flexible insulating material.

36. A method of insulating a building including: positioning a thermal insulating structure having an insulating body incorporating flexible insulating material and two flaps extending from opposite sides respectively of the insulating body in a space between two adjacent supporting members of the building; and securing the two flaps to the adjacent supporting members to fit the insulating body in the said space with sufficient drape to compensate for variations in the width of the said space such that the air space adjacent the insulation structure is at least substantially preserved.

37. A method according to Claim 36, wherein the insulation body is provided with two outer layers enclosing the flexible insulating material, and wherein the outer layers are extended beyond the flexible insulating material to form the flaps.

38. A method according to Claim 36 or Claim 37, further including: sealing any adjacent air space by extending the two flaps for the width of the supporting members.

39. A method according to any of Claims 36 to 38, further including: running the two flaps along, and over, an edge of the respective supporting member and fixing the flaps to the respective supporting members.

40. A method according to Claim 39, further including: wrapping the two flaps around two surfaces of the respective supporting members.

41. A method according to any of Claims 36 to 40, wherein the two flaps each have a length approximately equal to half the depth plus the width of the respective supporting member.

42. A method according to any of Claims 36 to 41 , further including: lining up markings on the two flaps with respective edges of the supporting members to position the insulation structure at a pre-determined depth within said space.

43. A method according to any of claims 36 to 42, further including: providing said space with at least one unobstructed air layer.

44. A method according to Claim 43, wherein the at least one unobstructed air layer is located below the insulation structure.

45. A method according to Claim 44, further including: providing two unobstructed air layers, one above and one below the insulation structure.

46. A method according to any of Claims 43 to 45, wherein at least one said unobstructed air layer is unventilated.

47. A method according to any of Claims 36 to 46, wherein the supporting members are rafters, wall studs or floor joists.

48. A method according to any of Claims 36 to 47, wherein the supporting members are rafters and further including positioning and securing respective said thermal insulating structures between adjacent rafters, fitting a breathable roofing membrane above the rafters to form an unventilated air space between the said thermal insulating structures and the breathable roofing membrane and fixing a continuous sheet of insulation below the rafters to form another unventilated air space between the said thermal insulating structures and the continuous sheet of insulation.

49. A modification of the method according to Claim 48, wherein the roof membrane is not breathable and the air space between the thermal insulating structures and the non-breathable roof membrane is ventilated.

50. A method according to any of Claims 36 to 49, further including: providing the insulating body with a width that is slightly wider than the width of said space.

51. A method according to any of Claims 36 to 49, further including: providing the insulating body with a width that is 10% greater than the width of said space.

52. A method according to any of Claims 36 to 49, wherein the space between the supporting members has a width of 400 or 600mm and wherein the insulating body has a width that is slightly greater than the supporting member space width.

53. A method according to any of Claims 36 to 49, wherein the insulating body has a width that is significantly greater than that of said space, the method further including: running side portions of the insulating body adjacent the flaps along respective facing surfaces of the adjacent supporting members and fixing the side portions of the insulating body to the adjacent supporting members.

54. A method according to Claim 53, further including: accommodating a rigid insulating material between the side portions of the insulating body adjacent the flaps such that the rigid insulating material extends between, and compresses, the flexible insulating material of the side portions of the insulating body in spaced apart relationship with that part of the insulating body which lies between its side portions.

55. A method according to any of Claims 36 to 54, further including: installing two said thermal insulating structures in the space between the adjacent supporting members from either one side or the other side of the supporting members.

56. A method according to any of Claims 36 to 54, further including: installing two said thermal insulating structures in the space between the adjacent supporting members from both sides of the adjacent supporting members.

57. A method according to any of Claims 36 to 56, wherein the two flaps are fixed to the supporting members by stapling, nailing, taping, screwing or gluing.

58. A building whenever insulated by at least one thermal insulation structure according to any of Claims 1 to 35 or by the method of any of Claims 36 to 57.