GB2409213A

GB2409213A - Breathable insulation material; preventing condensation in insulated spaces

Info

Publication number: GB2409213A
Application number: GB0427630A
Authority: GB
Inventors: Jack Irvine Davidson Shaw
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-12-17
Filing date: 2004-12-15
Publication date: 2005-06-22
Anticipated expiration: 2024-12-15
Also published as: GB0427630D0; GB2409213B; GB0329172D0

Abstract

Condensation is prevented in a space, such as a roof insulated by sheets or boards 3 of insulating material, by providing within or between at least a portion of adjacent sheets 3, or in an aperture or recess extending through a sheet 3, a region 20 of water vapour permeable material to permit escape of water vapour. Sheets 3 may be above rafters 1 as shown, and may be of rigid phenolic or urethane board. The water vapour permeable material 20 may be reticulated polyester based polyurethane open celled foam or may be a mat of fine spun polyester strands: it may be provided with a layer 22 of paper, metal foil or PVC on opposite sides thereof, bearing an adhesive layer.

Description

240921 3

BREATHABLE INSULATION MATERIAL AND METHOD OF PREVENTING

CONDENSATION IN INSULATED SPACES

The present invention relates to a breathable insulation material for insulating buildings and in particular loft spaces, walls and flat roof voids, and to a method of preventing condensation in insulated spaces, in particular warm loft spaces.

In order to comply with building regulations and to conserve energy by reducing heat loss, buildings must be completely sealed and thermally insulated, the requirements for such thermal insulation being set out in The Building Regulations 2001 (England and Wales) Approved Documents L1 & L2. All plans submitted for Building Control approval must comply with such regulations.

Such regulations set out maximum permissible levels of energy transference (the so called U value) for specific building elements of domestic dwellings.

Such levels are currently 0.20 W/m2K for rooms in the roof space, 0.16 W/m2K for lofts, 0.25 W/m2K for flat roofs, 0.35 W/m2K for walls, 0.25 W/m2K for floors and 2.00 to 2.20 W/m2K (depending on the type of frame) for windows, doors or roof lights.

In order to provide the required thermal insulation, different insulating materials have been developed, the thickness of a particular material required to meet the necessary insulation requirements depending on the insulating properties of the material in question. A popular material, particularly for the insulation of walls and loft spaces and flat roof voids is rigid phenolic resin or rigid urethane resin insulation board. Such material provides the required insulation with the minimum thickness and thus is frequently used in loft conversions to provide insulation between and under the rafters to maximize the available loft space. If a non-breathable bitumous roofing membrane is used (commonly referred to as Barking felt) the insulating boards must be spaced from the roofing membrane to provide at least a 25mm deep ventilated air space above the insulating boards. To avoid the need for such an air space, breathable roofing membranes are frequently used whereby it is permitted to position the insulating boards directly against the roofing membrane.

To ensure the continuity of the insulation, the sides of adjacent insulation boards are abutted against one another and an adhesive foil tape is placed over the abutting surfaces or seams to provide a continuous air tight and waterproof seal.

Such rigid phenolic or rigid urethane insulation boards are also frequently used to insulate walls between studs, behind the plaster board and also may be used in cavity walls, on floors and flat roof voids.

Manufacturers of such rigid phenolic or rigid urethane insulation boards have stated that the creation of a warm roof space using such insulation boards negates the need for roof space ventilation. However, it has been found that condensation can occur on the underside of the insulation boards, in particular on the taped joints where cold bridging occurs, such condensation leading to mould growth on the rafters and on goods and furnishings placed in the loft space and eventually to rotting of the rafters. Since hot moist air tends to rise to the highest point within a house, the lack of any ventilation at the apex of the roof space leads to condensation problems in such region. The rigid phenolic or urethane resin insulation boards are impermeable to water vapour, the escape of such moisture through the insulation is prevented and the moisture is retained in the loft space, leading to condensation problems.

Thus there exist conflicting requirements of continuity of the insulation in the roof space to achieve the required degree of insulation and the need for the removal of vapour from the roof space to reduce the risk of condensation.

The present invention solves the abovementioned problem by providing a method of preventing condensation in an insulated space, said space being insulated by means of a plurality of sheets or boards of insulating material, said method comprising the steps of providing between and/or within at least a portion of adjacent sheets of insulating material or in at least an aperture or recess extending through at least one sheet of insulation material, at least one region of water vapour permeable material to permit the passage of water vapour from the insulated space.

In a preferred embodiment said vapour permeable material, which contributes to the thermal insulation, preferably comprises a reticulated polyester based polyurethane open cell foam, preferably having a density of between 26 and 32 kg/m3, a cell count of between 14 and 21 cells /cm and a pore size of between 10 and 100 pores per inch and more preferably between 60 and 80 pores per inch.

Such materials are frequently used to for air filtration and allow the passage of water vapour while providing relatively good insulation properties.

In an alternative embodiment said vapour permeable material comprises a mat of fine spun polyester strands.

According to a further aspect of the present invention there is provided means for preventing condensation in an insulated space, said space being insulated by means of a plurality of sheets or boards formed from an air and vapour impermeable insulating material, said means comprising at least one elongate body of water vapour permeable material, preferably having securing means on opposite sides thereof, whereby the ventilation means can be secured, in use, between at least a portion of adjacent sheets or boards, or within one or more apertures or recesses formed therein.

Preferably said securing means comprise a layer of sheet material, such as paper, metal foil or a polymeric material (such as PVC), secured on at least each of said opposite sides of the body of vapour permeable material, an adhesive material being provided on a side of each of said layers of sheet material remote from the body of vapour permeable material.

Preferably said vapour permeable material comprises reticulated polyester based polyurethane open cell foam, preferably having a density of between 26 and 32 kg/m3, a cell count of between 14 and 21 cells /cm and a pore size of between 10 and 100 pores per inch and more preferably between 60 and pores per inch. Alternatively said vapour permeable material comprises a mat of fine spun polyester strands.

According to a further aspect of the present invention there is provided breathable insulating means comprising a board or sheet of insulating material having secured to at least a portion of a side thereof or within an aperture or recess therein a region of water vapour permeable material.

Preferably said insulating material comprises rigid phenolic or urethane resin.

Preferably said vapour permeable material comprises reticulated polyester based polyurethane open cell foam, preferably having a density of between 26 and 32 kg/m3, a cell count of between 14 and 21 cells /cm and a pore size of between 10 and 100 pores per inch and more preferably between 60 and pores per inch. Alternatively said air and moisture permeable material comprises a mat of fine spun polyester strands. Still further alternatively, the vapour permeable material may be a mixture of said foam and spun polyester strands. The vapour permeable material may be any suitable shape such as a cube, a rectangular block or cylinder. A cylinder of impermeable material may be located in a circular aperture extending through a board of insulating material which aperture may be formed by a circular drill biVtubular drill bit The present invention will be described further, by way of example, with reference to the accompanying drawings, in which: Fig. 1 shows an insulated warm roof structure in accordance with the present invention with a truss rafter type pitched roof assembly; Fig. 2 shows a lower region of the roof structure of Fig. 1; Fig. 3 shows a view of the roof structure of Fig. 2 from below in direction A shown in Fig. 2; and Fig. 4 shows an insulated warm roof structure in accordance with the present invention with a traditional ridge board type pitched roof assembly.

As shown in Fig. 1 the roof structure comprises a plurality of spaced inclined pairs of roof rafters 1,2. Rigid phenolic or rigid urethane insulation boards 3 are placed on top of the rafters 1,2 to insulate the roof space, said insulation boards 3 abutting one another to provide an unbroken insulating layer.

Alternatively, the insulation boards 3 may be mounted between the rafters so that the outer surfaces of the insulation boards 3 are level with the outer face of the rafters 1, 2. Abutting seams between adjacent insulation boards 3 may be covered by adhesive metallic foil or PVC tape to provide a secure join.

Counter battens 4 are mounted on top of and parallel to the rafters 1, 2 and are secured to the rafters 1, 2 by suitable fastening means, such as nails.

Where the insulation boards 3 are placed on top of the rafters 1,2 the counter battens 4 will lay on top of the insulation boards 3 and the securing means will pass through the insulation boards into the rafters 1, 2 therebeneath.

One or more sheets of roofing felt in the form of a breathable membrane 5 are placed over the top of the counter battens 4 and are secured taught over the roof structure.

Substantially horizontally arranged tile battens 6 are secured over the breathable membrane 5 and counter battens 4 to provide support for tiles 7.

In order to prevent the risk of condensation within the roof space, an elongate slot or recess 3A is cut into a central region of the uppermost edge of each insulation boards 3 adjacent the ridge of the roof structure and extending through the board 3 and into which slot or recess is secured a strip of breathable material 10. Moisture within the roof space is able to pass through said the breathable material 10 and subsequently such moisture can diffuse through the breathable membrane 10 and into the space beneath the ridge tile 11. It has been found that 20mm wide and 255mm long strips of breathable material, secured into a correspondingly dimensioned slot or recess provided in the upper edge of each insulation board 3 adjacent the roof ridge or between the edges of adjacent insulation boards 3, provides the desired degree of vapour transmission.

In order to provide ventilation of the space above the breathable membrane 5 one or more ventilated roof ridge tiles 11, as disclosed in GO 2,359,568, may be used.

As shown in Figs. 2 and 3, where the rafters are more than 5m long, a further 10mm wide strip of breathable material 20 is provided in a slot of recess formed in a central region of adjacent sides of the insulation boards extending through the board and at a position am from the ridge, said breathable material 20 being permeable to water vapour and moisture.

For longer rafters, further 10mm wide strips of breathable material should be provided in suitably formed slots or recesses between adjacent sides of the insulation boards every 3m (i.e. at am spacings).

In order to prevent cold bridging the slots or recesses in the sides of the insulation boards 3 into which the breathable material 10, 20 is received should terminate at least 75mm from the sides of the rafters 1, 2.

As shown in Fig. 4, where the roof assembly includes a traditional ridge board to which the top ends of the rafters 1,2 are secured, a 10mm wide strip of breathable material 40,50 may be provided in a suitably dimensioned elongate slot or recess provided in a central region of the uppermost side of each insulation board 3 extending through the board from surface to surface of the board and adjacent each side of the ridge board 30. Thus in this embodiment the blocks of permeable material 40,50 are located in the recess on the edge of a board, flush with the edge, and abut the ridge board 30 instead of in the recess on the edge of adjacent board 3.

The breathable material 10,20,40,50 will preferably be such as to also contribute to the thermal insulation and preferably comprises an elongate strip of reticulated polyester based polyurethane open cell foam, preferably having a density of between 26 and 32 kg/m3, a cell count of between 14 and 21 cells /cm and a pore size of between 10 and 100 pores per inch and more preferably between 60 and 80 pores per inch. With boards 3 having upper and lower surfaces lying in the same plane, the upper and lower surfaces of breathable material 10, 20, 40, 50 will also be flush with the surfaces of adjacent board surfaces.

In an alternative embodiment the breathable material 10,20,40,50 may comprise a mat of fine spun polyester strands. Alternatively, a mixture of said foam and strands may be used, It is important to prevent moisture penetrating the cut recesses or apertures in the boards 3 and this may be achieved for example, either by treating such with a sealant prior to insertion of the breathable material, said sealant preferably also being an adhesive so as to also secure the breathable material, or may be a sealing tape 22.

Each strip of breathable material 10,20,40,50 is preferably sandwiched between layers of PVC or metallic foil tape 22 (see Figs. 1 and 3) having adhesive on both sides thereof, the width of the tape being greater than the width and thickness of the breathable strip whereby the breathable strip can be secured to the adjacent sides of the slot or recesses formed in the insulation boards 4, the ends of the tape 22 extending beyond the width of the breathable material being folded back and secured to the faces of the insulation boards 3 adjacent said slots or recesses.

More specifically, Fig. 3 is a fragmentary plan from above of four abutting boards with the breathable material 20 being in recesses in abutting edges of two boards 3 and is of a length and width as visible and a thickness equivalent to that of the boards 3. The recesses 3A when combined/adjacent are only slightly larger than the length and width of the material 20 to accommodate such and the thickness of tape 22 at its sides and ends but in adhered relationship.

The downwardly extending portions 22E, 22F of four parts 22A, 22B, 22C and 22D of tape 22 are adhered to the sides 3A and ends (not shown) of the recesses in the boards 3: The upper parts 22A-D are folded against the upper surfaces of boards 3 and the breathable material inserted and held in position by the adhesive. Alternatively, the parts 22A-D may be secured first to the permeable material 10 before insertion from above in the recess. The lower edges of the tape sides 22E, 22F extend below the surface of the boards 3 by a small amount, e.g. about 5mm to prevent "cold bridging" or water moisture going into the board material. Contrary to illustrated in Figs. 2 or 4, the tape 22 will preferably be on the top surface of planar boards 3 and thus projects slightly thereabove by the thickness of the material.

Instead of, or in addition to tape 22, the cut edges of the recess are sealed with suitable sealant which, when tape is not used, will preferably be adhesive to bond the permeable material in position.

In Fig. 4 the sealing and securing tape 22 may be similarly featured.

Whilst the embodiments described above are in relation to pitched roof structures, it is envisaged that the invention could also be applied to other insulated structures such as flat roofs, floors and studded walls. The breathable material of the invention may also be applied to boards formed from materials other than rigid phenolic or urethane resin, such as wood, rockwool, and other insulating but impermeable materials. The invention provides atmospheric ventilation breathable in an insulated space.

Claims

1. A method of preventing condensation in an insulated space, said space being insulated by means of a plurality of sheets or boards of insulating material, said method comprising the steps of providing between and/or within at least a portion of adjacent sheets of insulating material or in at least an aperture or recess extending through at least one sheet of insulation material, at least one region of water vapour permeable material to permit the passage of water vapour from the insulated space.

2. A method as claimed in claim 1, wherien said vapour permeable material comprises reticulated polyester based polyurethane open cell foam, preferably having a density of between 26 and 32 kg/m3, a cell count of between 14 and 21 cells /cm and a pore size of between 10 and 100 pores per inch and more preferably between 60 and 80 pores per inch.

3. A method according to claim 1, wherein said vapour permeable material comprises a mat of fine spun polyester strands.

4. Means for preventing condensation in an insulated space, said space being insulated by means of a plurality of sheets or boards formed from an air and vapour impermeable insulating material, and the ventilation means comprising at least one body of water vapour permeable material securable or secured, in use, between at least a portion of and/or in one or more recesses of adjacent sheets or boards, or within one or more apertures formed in at least one sheet or board.

5. Means as claimed in claim 4, in which the body of water permeable material is a cube, a rectangular elongate block, a cylinder or any other suitably shaped body.

6. Means as claimed in claims 4 or 5, wherein said securing means comprise a layer of sheet material, such as paper, metal foil or a polymeric material (such as PVC), secured on at least each of said opposite sides of the body of vapour permeable material, an adhesive material being provided on a side of each of said layers of sheet material remote from the body of vapour permeable material.

7. Means as claimed in any of claims 4 to 6, in which the securing means is provided on at least one side of or on opposite sides of or on all sides of said body.

8. Means as claimed in claim 6 or claims 6 and 7 in which said layer extends a short distance (such as about 5mm) beyond the lower surface of said board(s).

9. Means as claimed in at least claim 4, in which the means for securing is frictional engagement of the body of vapour permeable material with the adjacent edges of the board or boards or is an adhesive applied to the edges of the board(s), recess(es) or aperture(s).

10.Means as claimed in any of claims 4 to 9, wherein said vapour permeable material comprises reticulated polyester based polyurethane open cell foam, preferably having a density of between 26 and 32 kg/m3, a cell count of between 14 and 21 cells /cm and a pore size of between 10 and 100 pores per inch and more preferably between 60 and 80 pores per inch.

11.Means as claimed in any of claims 4 to 10, wherein said vapour permeable material comprises a mat of fine spun polyester strands.

12.Means as claimed in at least claims 10 and 11, in which said vapour permeable material is a mixture of open cell foam and polyester strands.

1 3.A breathable insulating means comprising a board or sheet of insulating material having secured to at least a portion of a side thereof or recess therein or within an aperture therethrough, a region of water vapour permeable material.

14.A breathable insulating means as claimed in claim 13, wherein said insulating material comprises rigid phenolic or urethane resin.

15.A breathable insulating means as claimed in claim 13 or claim 14, wherein said vapour permeable material comprises reticulated polyester based polyurethane open cell foam, preferably having a density of between 26 and 32 kg/m3, a cell count of between 14 and 21 cells /cm and a pore size of between 10 and 100 pores per inch and more preferably between 60 and 80 pores per inch.

16.A breathable insulating means as claimed in claim 13 or claim 14, wherein said air and moisture permeable material comprises a mat of fine spun polyester strands or a mixture thereof with a reticulated polyester based polyurethane open cell foam.

17.An assembly of components for thermally insulating a space in a building including at least two sheets or boards formed from an air and vapour impermeable insulating material and abuttable on at least two edges, at least one ventilation means of water vapour permeable material securable between at least a portion of adjacent sides or recesses of the sheets or boards, or within one or more apertures formed extending through at least on said sheet or board.

18.An assembly as claimed in claim 17, in which the edge of each sheet or board which is to abut another has a recess extending between the faces of the opposite main sides of the sheet or board and when two sheets and the recesses are juxtaposed, the permeable material is locatable to extend between the two sheets and substantially fill the juxtaposed recesses or may be in two parts with the dividing line along the plane of the abutment of the two sheets or boards.

19.A means as claimed in any of claims 4 to 7 or claims 12 to 16, in which the edges of the recess and/or apertures are sealed against the ingress of water or moisture by a sealant or a sealant with adhesive properties.

20.A building wherever having an insulated space provided by the method of any of claims 1 to 3, or including a space insulated with the means of any of claims 4 to 11 or the means of any of claims 13 to 16 or the assembly of claims 17 or 18.

21.A method of preventing condensation in an insulated space substantially as herein described with reference to the accompanying drawings.

22.Means for preventing condensation in an insulated space substantially as herein described with reference to the accompanying drawings.

23.A breathable insulating means substantially as herein described with reference to the accompanying drawings.