WO2006062793A2

WO2006062793A2 - Fire resistant wall insulation

Info

Publication number: WO2006062793A2
Application number: PCT/US2005/043367
Authority: WO
Inventors: Charles R. Weir; Roy E. Shaffer
Original assignee: Owens Corning Intellectual Capital, Llc.
Priority date: 2004-12-09
Filing date: 2005-12-01
Publication date: 2006-06-15
Also published as: WO2006062793A3; US20070068104A1; CN101072919A; US20060123723A1; CA2588826A1; US20070068101A1

Abstract

Disclosed are an insulation product and an insulation system incorporating such a product for insulating exterior walls, particularly masonry walls, that incorporates at least one internal fire retardant layer (30) and, optionally, a wicking material (45) for transporting condensate away from the interface between the insulating product and the exterior wall. The insulation system includes an integrated support element (100) that can be used to increase the rate of evaporation via various methods, provide for the concealed distribution of cables and wiring and/or improve the aesthetic appearance of the insulating product.

Description

IMPROVED WALL FINISHING PANEL SYSTEM

TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY

This invention relates generally to a method and apparatus for insulating walls, particularly subsurface walls, that provides improved flame retarding performance and which may also provide improved moisture control at the interface between the insulation material and the masonry wall. More particularly, this invention pertains to an insulating process and apparatus in which at least one flame retardant layer is incorporated into an insulating system in combination with insulating materials for finishing walls and, for exterior or other cooled spaces, optionally including at least one layer of sorbent and/or wicking materials, for finishing walls.

BACKGROUND OF THE INVENTION

The exterior walls of a building are typically insulated in order to reduce the heating and cooling demands resulting from variations between the exterior temperature from the desired interior temperature. A wide range of fibrous, solid and foam insulating materials have been used to achieve this insulation, with a common insulating material being faced or unfaced batts of mineral or glass fibers. Interior walls, for example, walls that divide or define separate smaller spaces within the area bounded by the exterior walls may also include similar types of insulation for reducing heat and/or sound transmission through the walls.

When using a faced insulating product in which a facing layer, such as asphalt- coated Kraft paper or a polymeric film, is adhered to the insulating layer, the insulation product is typically installed with the facing layer positioned toward the interior space. This orientation tends to reduce infiltration or diffusion of the moisture-laden interior air through the insulating layer to the interface between the insulating product and the exterior wall. Particularly in climates with long heating seasons, high humidity and/or extremely cold temperatures, using faced insulation products limits the amount of moisture from the interior air that can reach the cooler exterior wall and condense to form liquid water on the surface of the exterior wall.

As used herein, masonry walls include constructions utilizing clay brick, concrete brick or block, calcium silicate brick, stone, reinforced concrete and combinations thereof. Water present at the interface between the insulating product and the inside surface of the exterior wall and/or the outer portion of the insulation product is associated with a host of problems including mold growth, efflorescence, reduced insulating efficiency and, if sufficiently cold, frost spalling resulting from water freezing and expanding within cracks and gaps in the masonry. A major contributing factor to the accumulation of water at the interface and the resulting decreased performance of the associated masonry wall system is the leakage of warm humid air through the building envelope to surfaces that are at temperatures below the dew point of the adjacent air and the associated accumulation of condensation within the insulating layer and/or on the inside surface of the exterior wall. Further, the use of such finishing and insulating systems for finishing residential basements can result in the materials being placed in general proximity to heated surfaces and potential ignition sources such as furnaces, boilers, water heaters, space heaters, etc. In recognition of these applications, the selection of and particular combinations of materials incorporated into such finishing and insulating systems should serve to suppress ignition and/or flame spread.

A need thus exists for improved systems and materials suitable for finishing and insulating both interior and exterior walls, that provides improved moisture control, particularly moisture resulting from condensation of water vapor on cool surfaces and improved flame retarding properties.

SUMMARY OF THE INVENTION

To solve the problems outlined above, the present invention provides an insulation product and an insulation system incorporating a flame retardant or fire inert filler material layer. The flame retardant layer will typically comprise a fiberglass mat into which one or more flame retardant or fire inert filler materials and/or additives have been incorporated.

As will be appreciated the selection and combination of the fillers and/or additives will be guided by the performance requirements and economic considerations. The performance of any particular combination may further be evaluated using one or more of a variety of industry recognized tests focusing on parameters such as flame spread, smoke generation, etc. to ensure that the product provides satisfactory performance. To the extent that such products may be used for finishing and insulating exterior walls, particularly masonry walls, or unheated spaces, the finishing system panels may also incorporate one or more layers or regions of wi eking media arranged to transport condensate from the interface between the insulating product and a cooled surface, such as an exterior wall, to a more interior location where it can evaporate and/or more or more sorbent material layers or regions for holding condensate. For example, an active layer or layers comprising one or more of a wicking fabric, wicking media and sorbent material may be provided on or near the exterior surface of the primarily insulating layer. When the insulating product is installed, the active layer will be closely adjacent and/or in contact with an inside surface of the exterior wall and thereby positioned to collect and/or redistribute condensate in a manner that will tend to maintain the insulating performance.

The insulation product is preferably installed with a corresponding support element to form an insulation system. The support element will typically be provided along the lower edge of the insulation product and define a space between the insulation product and the floor. The support element may comprise several cooperating elements or structures and may, for example, include a baseboard portion to create a more finished appearance for the interior surface of the insulation system.

This space defined by the support element portion of the insulation system may be used for routing an extension portion of the primary wicking material toward and/or into the interior space in order to increase the evaporation rate. Additional elements, such as vents, grills, fans, ducts, sorbent material, cable channels, secondary wicking materials and heaters, may be included in or connected to the support element for further improving the performance and versatility of the insulation system. Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: FIG. 1 is a vertical cross-sectional view of an exemplary embodiment of an insulation product and insulation system according to the invention;

FIG. 2 is a vertical cross-sectional view of another exemplary embodiment of an insulation product and insulation system according to the invention; FIG. 3 is a vertical cross-sectional view of another exemplary embodiment of an insulation product and insulation system according to the invention;

FIG. 4 is a vertical cross-sectional view of another exemplary embodiment of an insulation product and insulation system according to the invention;

FIG. 5 is a vertical cross-sectional view of another exemplary embodiment of an insulation product and insulation system according to the invention;

FIG. 6 is a vertical cross-sectional view of another exemplary embodiment of an insulation product and insulation system according to the invention;

FIG. 7 is a horizontal cross-sectional view of another exemplary embodiment of an insulation product and insulation system according to the invention as may be applied to new construction; and

FIG. 8 is a horizontal cross-sectional view of another exemplary embodiment of an insulation product and insulation system according to the invention as may be applied to existing construction.

These drawings have been provided to assist in the understanding of the exemplary embodiments of the invention as described in more detail below and should not be construed as unduly limiting the invention. In particular, the relative spacing, positioning, sizing and dimensions of the various elements illustrated in the drawings are not drawn to scale and may have been exaggerated, reduced or otherwise modified for the purpose of improved clarity. Those of ordinary skill in the art will also appreciate that a range of alternative configurations have been omitted simply to improve the clarity and reduce the number of drawings.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

As shown in FIG. 1, the insulation system 1 may be installed adjacent an inside surface of an exterior wall or a framing assembly 50 and above a floor 60. The insulation system may include a supporting member or frame 100 that may be attached using fasteners 105 or adhesives (not shown) to the floor 60, a cover layer 10, typically a woven or non-woven fabric sheet, which may comprise one or more polyolefϊns or other natural or synthetic fibers, fillers, dyes, stabilizers, etc., to provide a more aesthetically pleasing appearance, a primary insulating layer 20, typically a semi-rigid fiberglass, which may be permeable to water vapor 12, mineral fiber web or a foam sheet, a fire retarding layer 30, and a secondary insulating material 40, again typically a semi-rigid fiberglass, mineral fiber web or a semi-rigid foam product such as Owens Comings'

FOAMULAR®, provided on the outside surface of the fire retarding layer. The primary and secondary insulating materials 20, 40 may be attached to the flame retarding layer 30 using any suitable method such as melt bonding, discontinuous adhesive layers, pinning or mechanical fasteners. In applications in which condensation is expected or may occur, a space may be provided below the secondary insulating layer 40 to reduce the likelihood that condensate will be trapped at the interface between the secondary insulating layer and the wall 50. As will be appreciated, the supporting member or frame 100 maybe provided with, incorporate or cooperate with a range of structures, devices or fixtures including, for example, flanges, clips and retainers (not shown) to allow the composite panel to be removably fixed in position relative to the supporting member 100. The supporting member 100 may also cooperate with vertical frame members for positioning the adjacent edge surfaces of adjoining panels relative to one another to improve the finished appearance of the installed product.

As used herein, the terms primary and secondary insulating materials relate to the relative position of the two layers in the illustrated embodiment with the primary insulating material being closer to the insulated space. Those of ordinary skill in the art will appreciate that the relative thickness and material selection for these two insulating materials can be customized to meet performance goals for various applications. The relative contribution of the two insulating layers to the overall R-value of the insulating product will necessarily vary with their relative thicknesses and compositions and may be relatively equal or may be heavily skewed toward one of the layers. For instance, one exemplary embodiment may be configured whereby the secondary insulating material layer would be rated a R- 10 while the primary insulating material would only be rated at R-3 to R-4. The selection of the appropriate materials and thicknesses for a given application may be guided by reference materials readily available to those of ordinary skill in the art.

A second embodiment is illustrated in FIG. 2 in which the flame retarding layer is attached to the secondary insulating layer using mechanical fasteners 70 such as pins, staples or other suitable means to maintain the relative positioning of the two layers. A third embodiment is illustrated in FIG. 3 in which the flame retarding layer 30 is attached to the primary insulating layer 20 using a discontinuous adhesive or melt bonding points 80 to maintain the attachment between the two layers. A fourth embodiment is illustrated in FIG. 4 in which the flame retarding layer 30 is attached to the secondary insulating layer 40, again using a discontinuous adhesive or melt bonding points 80. As also illustrated in FIG. 4, the supporting member or frame 100 may be attached to the floor 60 using an adhesive layer 110, such as an epoxy resin, rather than the mechanical fasteners 105 as illustrated in FIG. 1. The point attachments 80 are useful for generally maintaining the vapor permeability of the two joined layers. In the event that one or more of the layers is generally impermeable to vapor or vapor permeability is not a concern, it will be appreciated that a continuous adhesive layer or sheet (not shown) may be used to attach the respective layers within the insulating system. A fifth embodiment is illustrated in FIG. 5 in which a wicking layer 45 has been incorporated into the insulating system generally illustrated in FIG. 4. This embodiment would have particular utility for insulating below grade masonry walls or other exterior walls that are expected to reach temperatures below the dew point of the air enclosed within the finished space and/or may continuously or periodically extrude or seep moisture. The wicking material is arranged to collect and transport any such liquid, whether seepage or condensate, from the interface between the wall and the insulating system to an exposed area 45a that will allow for evaporation or other removal means and thereby prevent or reduce any significant collection of liquid at the interface.

A sixth embodiment is illustrated in FIG. 6 wherein the supporting structure or base 100 is attached to the wall 50 with a fastener 105 and/or an adhesive (not shown). The base 100 is configured to receive an external trim, fascia or finish piece 102 that can be configured to provide external openings or vents 106 for improving the evaporation of collected and transported liquid from the terminal portion 45a of the wicking layer 45 and may have an extension 104 that is configured to establish a friction fit with the base structure 100 that will tend to hold the terminal portion of the wicking layer in place. The base structure 100 may also provide one or more channels, guides or races 44 for communication cable, networking cable and/or power cable distribution 46 concealed within the base structure while still keeping the cables readily accessible for reconfiguration.

As illustrated in FIGS. 7 and 8, the insulating system 1 may be used to finish walls 50 in new construction, FIG. 7, and which may include a wicking layer 45, or used to finish over existing walls, FIG. 8, in which case the incorporation of a vapor barrier layer may be helpful. As illustrated in FIG. 7, the insulating system 1 may be installed directly adjacent a wall 50, for example a brick, block or concrete wall, and may be provided with a wicking layer 45 for removing liquid from the interface between the insulating system and the wall. The insulating system 1 may include a number of vertical splines or frame portions 115 that may cooperate with the support element 100 (not shown) for holding and positioning the insulating composite panel portions of the insulating system.

As illustrated in FIG. 8, when a conventional frame wall will framing members 61 and soft batt or other insulation 59 already in place, the insulating system 1 maybe applied directly over the existing structure and may utilize one or more barrier layers such as asphalt-coated kraft paper 57 and/or a vapor retarding layer 55 such as TYVEK® to seal the existing structure before applying the insulating system 1 to the wall. Depending on the finishing requirements, the frame members may also be adapted to accommodate conventional drywall or other panels (not shown) suitable for painting or other finishing techniques. In such instances, the finish layer 10 may be omitted from the insulating system composite panels.

The flame retarding layer 30, will typically comprise a fiberglass mat that incorporates one or more flame retardant fillers and/or flame retardant additives. Exemplary flame retardant fillers and additives include, for example, alumina trihydrate (ATH) (Al₂O₃ • 3H₂O), hydrated zinc borate (ZnB₂O₄ • 6H₂O), calcium sulfate (CaSO₄ • 2H₂O) also known as gypsum, magnesium ammonium phosphate (MgNH₄PO₄ • 6H₂O), magnesium hydroxide (Mg(OH)₂), ZnB, clay, calcium carbonate, carbon black, acid intercalated graphite, micro encapsulated H₂O, halogenated fire suppressants, intumescent phosphate compounds such as ammonium polyphosphate, organic and inorganic phosphate compounds, sulfate and sulfamate compounds such as ammonium sulfate and free radical scavenger materials such as antimony trioxide. Those of ordinary skill in the art will appreciate that this list is exemplary only and that other suitable compounds may be utilized to improve the fire retarding properties of the fiberglass mat.

The flame retarding layer 30, may also incorporate materials intended to reduce radiant heat transfer through the layer. Exemplary radiant barrier materials include, for example, fine metal particles, metal coated particles or metal films that will tend to reflect radiant energy and reduce the heating of materials, such as the primary insulating layer 20, protected by the flame retarding film 30. Thus positioned between insulating layers, the fire retarding layer 30 will improve the fire retarding performance of the insulating system without significantly affecting the handling and appearance of the insulating panel.

When utilized, the wicking material 45 will preferentially collect condensate from water vapor that has diffused through or around the insulating system 1 from the finished interior space, typically a heated room, to a point near or at the cool, inside surface of an exterior wall 50 when the temperature of the wall is below the dew point of the air reaching the wall. Similarly, the wicking material 45 will collect water that diffuses or seeps through the masonry wall 50 from its outside surface, particularly for subsurface portions of the exterior wall that are not completely sealed. In addition to seepage, it will be appreciated that in those regions subject to periods of hot, humid weather, water vapor diffusing from the environment outside the exterior wall may condense as it reaches the cooler inside surface resulting from the air conditioning of the interior space.

The wicking material 45 is preferably a non-woven material that can be formed from a polymer or natural fiber. One suitable polymer for manufacturing the wicking material is rayon. Rayon fibers may be striated, or include channels, along the length of the fiber, which provide capillary channels within the individual fibers so the wicking action does not depend solely upon capillary action resulting from the channels formed between two adjacent fibers.

In addition to rayon fibers, other polymeric fibers including polyester, nylon, polypropylene (PP) and polyethylene terephthalate (PET), may be manufactured or processed in a manner that will produce fibers including striations or channels on their surface. A number of fiber configurations have been developed that provide a plurality of surface channels for capillary transport of water and have been widely incorporated in active wear for improved comfort. These types of materials can be collectively referred to as capillary surface materials (CSM) and include so-called deep-grooved fibers that have high surface area per unit volume as a result of their complex cross-sectional configuration. The capillary material layer can be provided in different configurations including, for example, a non-woven film or a fine mesh configuration. As a result of gravity, the wicking material 45 will tend to transport any water collected at the interface between the insulating system 1 and the exterior wall 50 downwardly along the interface and, near the lower edge of the insulation product into a terminal portion 45a that may be arranged inwardly toward the interior space or in an opening provided within the base structure 100 to allow for evaporation, collection or secondary removal techniques. Preferably, the terminal portion 45a will be sized or otherwise configured to provide for a removal or evaporation rate for the transported fluid sufficient to avoid or reduce undesirable accumulation of liquid within the insulating system or at the interface with the exterior wall.

There are several methods to form the wicking material which may be configured as a non- woven film and/or as a relatively fine mesh. The fibers can be laid down dry with an acrylic emulsion being applied to the fibers and then cured by heating or UV radiation exposure. Standard fiber binding emulsions such as acrylic or EVA (ethylene vinyl acetate) can be utilized.

In another embodiment of the invention the insulating system of FIG. 5 may be modified with a layer of sorbent material replacing or supplementing the wicking material 45. These embodiments may be used to provide for the absorption of water in excess of the volume that can be successfully transported through the wicking material 45 and thereby reduce the likelihood of water accumulating on the inside surface of the exterior wall 50 even during periods of excessive condensation or seepage. The sorbent material (not shown) may cooperate with the wicking material 45 to provide a

"damping" effect whereby periodic increases in the volume of water can be removed over a longer period of time and reduce the volume of fluid the wicking material is required to remove the condensate from the interface region. The sorbent material layer may be a separate premanufactured layer that is laminated to the secondary insulating layer 40 along with the wicking material 45 or may be incorporated in the primary or secondary insulating material(s) 20, 40 or flame retarding layer 30 as a liquid and then dried, cured and/or activated to form sorbent region(s). Depending on the volume of condensate and seepage that are anticipated for a particular installation, the wicking material 45 present in the insulation product illustrated in FIGS. 5 and 6 may be replaced by a separate layer of sorbent material. Such an embodiment may be of particular utility for installations in which brief periods of high humidity are separated by longer periods of relatively low humidity. In such an environment, the sorbent material layer will collect and hold the condensate formed from diffusing moisture during periods of high humidity and allow the water vapor to evaporate and diffuse back through the primary insulating layer 20 and cover layer 10 during periods of low relative humidity, thereby reducing or preventing the formation of water on the inside surface of the exterior wall 50. A variety of sorbent materials may be used to form the sorbent material layer, but will generally be characterized by their ability to absorb and hold at least about five times, and preferably at least about ten times, their weight in water.

As reflected in the figures discussed above, the primary support element 100 and/or the trim element 102 (where shown) may be provided in a larger number of configurations and may be manufactured from a large number of materials suitable for extrusion or other forming techniques such as various polymers and metals. The supporting element or structure 100/102 maybe configured to provide one or more additional elements or structures that will tend to increase the rate of evaporation of the water and/or condensate that reaches the terminal portion 45 a of the wicking material 45 and may utilize a secondary wicking material (not shown).

As will be appreciated, the secondary evaporative and/or wicking material may assume a wide range of configurations within, and/or partially without, the support element 100/102. It will also be appreciated that the particular embodiments illustrated and discussed herein, while exemplary, are not to be considered limiting or exhaustive and that a wide variety of configurations maybe utilized to achieve the desired functionality and/or adapt the insulating system for more and less challenging conditions.

The principle and mode of operation of this invention have been described in its preferred embodiments. However, it should be noted that this invention may be practiced otherwise than as specifically illustrated and described without departing from its scope.

Claims

WHAT IS CLAIMED IS:

1. A wall insulation product comprising a primary insulating layer (20) having a interior surface and an exterior surface; a secondary insulating layer (40) having a interior surface and an exterior surface; and a flame retarding layer (30) arranged between the primary and secondary insulating layers.

2. A wall insulation product according to claim 1, further comprising a wicking material (45) having a primary portion provided on the outer surface of the secondary insulating layer for collection and transport of a liquid and a terminal portion configured for evaporation of the liquid.

3. A wall insulation product according to claim 2, further comprising a vapor retarding layer (55) provided on the inner surface of the primary insulating layer.

4. A wall insulation product according to claim 2, wherein the wicking material covers substantially the entire outer surface of the secondary insulating layer.

5. A wall insulation product according to claim 2, further comprising a sorbent region provided adjacent the wicking material.

6. A wall insulation product according to claim 5, wherein the sorbent region is formed by coating an outer region of the secondary insulating layer with a sorbent material.

7. A wall insulation product according to claim 5, wherein the sorbent region is separate material layer provided between the secondary insulating layer and the wicking material.

8. A wall insulation product according to claim 1, wherein the flame retarding layer comprises a mineral fiber mat impregnated with at least one flame retardant filler.

9. A wall insulation product according to claim 8, wherein the flame retardant filler is selected from a group consisting of alumina trihydrate (ATH) (Al₂O₃ • 3H₂O), hydrated zinc borate (ZnB₂O₄ • 6H₂O), calcium sulfate (CaSO₄ • 2H₂O), magnesium ammonium phosphate (MgNH₄PO₄ • 6H₂O), magnesium hydroxide (Mg(OH)₂), ZnB, clay, calcium carbonate, carbon black, and intercalated graphite.

10. A wall insulation product according to claim 8, wherein the flame retardant filler is selected from a group consisting of micro encapsulated water, halogenated fire suppressants, intumescent phosphate compounds, organic and inorganic phosphate compounds, sulfate and sulfamate compounds and free radical scavengers.

11. A wall insulation product according to claim 8, wherein the mineral fiber is selected from a group consisting of fiberglass, mineral wools and alkali earth oxide fibers.

12. An insulation product for exterior walls according to claim 2, wherein the terminal portion of the wicking material is arranged and configured to extend beyond a plane defined by the inner surface of the primary insulating layer and into a finished space.

13. A wall insulating system comprising an insulating element including: a primary insulating layer (20) having an inner surface, an outer surface and lower surface; a secondary insulating layer (40) having an inner surface, an outer surface and lower surface and a flame retarding layer (30) arranged between the inner surface of the primary insulating layer and the outer surface of the secondary insulating layer; and a supporting element (100) arranged and configured to support the insulating element adjacent a wall.

14. A wall insulating system according to claim 13, further comprising a wicking layer (45) arranged between the inner surface of the secondary insulating layer and the wall for collection and transport of a liquid and a terminal portion positioned below the lower surface of the secondary insulating layer; and the supporting element arranged and configured to accommodate the terminal portion of the wicking material.

15. A wall insulating system according to claim 14, further comprising a sorbent material provided within the supporting element and in contact with the terminal portion of the wicking material.

16. A wall insulating system according to claim 14, further comprising a sorbent material provided between the secondary insulating layer and the wicking material for absorbing excess liquid from the wicking material.

17. A wall insulating system according to claim 14, further comprising a heating element provided within the supporting element and in proximity to the terminal portion of the wicking material.

18. A wall insulating system according to claim 14, further comprising a secondary evaporative material provided within the supporting element and in contact with the terminal portion of the wicking material for receiving a portion of the liquid from the wicking material.

19. A wall insulating system according to claim 14, wherein the supporting element includes a plurality of openings whereby vapor evaporating from the terminal portion of the wicking material may pass into an insulated space.

20. A wall insulating system according to claim 13, wherein the supporting element includes a trim element (102) that extends to a lower peripheral portion of an inner surface of the insulating element.

21. A wall insulating system according to claim 13, wherein the flame retarding layer comprises a mineral fiber mat impregnated with at least one flame retardant filler.

22. A wall insulating system according to claim 21, wherein the flame retardant filler is selected from a group consisting of alumina trihydrate (ATH) (AI₂O₃ • 3H₂O), hydrated zinc borate (ZnB₂O₄ • 6H₂O), calcium sulfate (CaSO₄ • 2H₂O), magnesium ammonium phosphate (MgNH₄PO₄ • 6H₂O), magnesium hydroxide (Mg(OH)₂), ZnB, clay, calcium carbonate, carbon black, and intercalated graphite.

23. A wall insulating system according to claim 22, wherein a secondary flame retardant is incorporated into the flame retarding layer, the secondary flame retardant being selected from a group consisting of micro encapsulated water, halogenated fire suppressants, intumescent phosphate compounds, organic and inorganic phosphate compounds, sulfate and sulfamate compounds and free radical scavengers.

24. A method for insulating walls, the method comprising: fastening a primary support element (100) adjacent the exterior wall (50); installing an insulating element adjacent the exterior wall, a lower surface of the insulating element being supported by the primary support element, the insulating element including an primary insulating layer (20), a secondary insulating layer (40) and a fire retarding layer (30) arranged between the primary and secondary insulating layers; installing a trim element (102) on the primary support element, the trim element including a portion covering a lower peripheral surface of the insulating element.

25. A method for insulating walls according to claim 24, further comprising securing an extended portion of the flame retarding layer between cooperating structures provided on the primary support element and the trim element.