The first BBA certificate for multi-layer thermal insulation was awarded in October 2006. This type of thermal insulation performance on the product was tested, under beams, in a protected hot box, to BS EN ISO 8990, resulting in on a thermal resistance, or R-value of 0.91 m2K/W for the core plus 1.69 m2K/W for the core plus 2 adjacent air layers. These values include the cold bridging effects of the slats. Manufacturers had designed a wide range of hybrid systems, fusing multi-foil thermal insulation with perhaps mineral or glass wool, or rigid polyurethane plates to provide U-values that would then comply with Approved Document Part L. Alternative substances including wool and Cellulose balls can be used in conjunction with multi-ply insulation.
If you choose to use today’s thermal insulation technology for a loft conversion, compared to more traditional materials on the market, multi-layer insulation can reduce insulation thickness and save you valuable space within the structure. This would be of the utmost importance, for example, in loft conversions where you would want to conserve headroom.
By using a thermal insulation that has been specifically designed for loft conversions, the free space inside the room will have a slight gain and the work to be done will have been reduced to 3 easy operations. In fact, if you later decided to implement an insulating gypsum board with all of the rigid foam already adhered to the gypsum board, you would reduce this task to just two operations. Unpleasant and time-consuming tasks, for example joist decking, glass wool installation, which requires a protective mask, or the need to cut stiff boards to fasten between joists, are no longer necessary. An independent evaluation by a Chartered Surveyor suggests that the multi-ply option could easily provide you with a 30% reduction in labor time compared to the polyurethane plate option.
When considering timber framed structures, bba BBA certificates have previously been issued allowing the use of multiple sheets in timber framed walls, such as dormer cheeks, and certificates for full size walls are also being processed. Thermal insulation would be applied inside the studs, then with drywall and batten, this will provide a vapor barrier as well as an air gap and cavity to allow for the completion of services. Glass wool or stiff board is then applied between the studs, which will give the required U-value. The benefits are that wood stud sizes can be smaller, and then the required U-value is achieved. Alternatively, the stud size can be maintained but even lower U-values can be achieved.
This exceptional product, breathable insulation, provides multi-ply insulation with a shingle base, and will be installed over existing insulation, for example when roof upgrades or renovations are completed, negating the risk of condensation.
Tested by standard methods and certified by the BBA, multi-ply insulation substances have a role to play in both new construction and renovation projects. Manufacturers are developing innovative thermal insulation products that are sure to play an increasingly important role as the performance demands of multi-layer thermal insulation increase.