Timber PAK (SW) Ltd, a specialist in closed
panel timber frame manufacture from a dedicated factory in Ivybridge, Devon, was given the contract to construct the apartments in structural timber. This involved the production of closed and insulated wall panels, followed by delivery and installation on-site, ensuring strict build tolerances and timescales were met.
Key objectives of the closed wall panel construction were to retain the structure’s thermal efficiency whilst at the same time reducing material cost, with no impact on the build’s labour cost, making sure that the target U-value of 0.19W/m²K for the wall was achieved. Turning to Protect Membranes, Timber PAK sought an innovative solution through the use of reflective membranes within still airspaces, with a need to value engineer on materials yet deliver the all-important sustainability driver of thermal performance.
After Timber PAK undertook a detailed consultation with Protect’s Technical team about potential solutions that could both meet the target 0.19W/m²K U-value and reduce the requirement for PIR insulation, alongside detailed condensation risk analysis, a selection of U-value calculations were provided.
This featured a combination of three low emissivity, insulating and reflective membranes from Protect – often referred to as the '3 is the Magic Number' solution.
Following on from this, the initial design of the closed wall type for this project was amended to incorporate a 20mm unventilated cavity within the 140mm closed panel, where Protect TF InterFoil, a reflective, internal and vapour permeable wall membrane would be fixed to the studs with the upper foil surface facing externally into the cavity. Protect VC Foil Ultra, a reflective air and vapour control layer, was then recommended to be used back to back with Protect TF InterFoil, with the foil facing internally into a service cavity created by a 38mm vertical batten. With the addition of Protect TF200 Thermo, the external, reflective breather membrane with the foil facing into the outer wall cavity, this combination of highly reflective membrane technology and cavities used in the design would help to ensure low emissivity could be achieved. This is turn would create a radiant barrier to prevent heat loss from the structure and deliver a collective energy efficiency benefit on the wall’s overall thermal performance.
This inventive solution was agreed by Timber PAK and was put into manufacture as part of a complete closed timber frame panel with all membranes precision fitted in factory controlled conditions, resulting in a complete wall system, designed to achieve reduced energy loss. In addition, the agreed wall detail allowed PIR material savings of 20mm to be made, whilst keeping within the wall footprint set by the client on the initial specification.
Ron Luker, Director at Timber PAK
(SW) Ltd commented,
“Having been a user of Protect’s reflective membranes for some years and an advocate of continued product development and performance, Timber PAK were delighted that Protect thought ‘out of the box’ for this project. The innovative idea to use TF InterFoil within a cavity designed into the closed panel allowed us to not only achieve our target U-value but also save money on insulation material – a win-win! The make-up with the three membrane solution is now one of our standard wall
types for clients and I would recommend this product combination for the more onerous new build specifications. Three is certainly the magic number for Timber PAK on this development!”
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