Wraptite®

Specifying a vapour permeable membrane in a facade, installed over a sheathing board, is a proven way to protect the structural frame. It can also deliver building performance, especially if it serves as the airtightness line too. In this month’s FAQs, the team at A. Proctor Group answer questions about comparing different vapour permeable membranes, and challenging performance claims made by manufacturers.

What role does a vapour permeable membrane play in a facade?

Uncontrolled air leakage through cracks, gaps and improperly sealed elements in a building façade contribute to a significant reduction in the energy efficiency of the entire construction. In some case, such air leakage can reduce the effectiveness of an insulated envelope by up to 70%. Ensuring airtightness is crucial in mitigating heat loss and minimising building emissions. The A Proctor Group provide the Wraptite membrane to facilitate better airtightness across the façade. This is our fully self-adhered, airtight and vapour permeable membrane, which is fully BBA certified for use in walls, roofs and floors. It is also a Passive House certified airtightness component, and has been used to achieve very low levels of air permeability.

Wraptite has potential uses across a number of applications, from spanning sheathing boards on framed buildings; to diminishing draughts in masonry walls. It is typically applied across the sheathing board on timber or steel framed roofs and walls, or over other monolithic elements such as a CLT structure.

• Self adhered
• Airtight yet vapour permeable
• No ventilation required
• Can be used in all wind zones
• No maintenance required
• Class B, s1 d0 in accordance with BS EN 13501-1:2007
• BBA Certified (Cert. No. 15/5274)
• Tough 3-Layer Laminate resists punctures and tears
• Lightweight and easy to install
• Wide service temperature range
• Can be left exposed for up to 90 days (North America) or 120 days (UK) during construction (Please contact the A. Proctor Group’s technical department for advice on specific geographical locations)
• Free from Volatile Organic Compounds

Cross Laminated Timber, or CLT, is an engineered timber product that consists of planks of sawn, glued, and layered wood, where each layer is oriented perpendicular to the previous. By joining layers of wood at perpendicular angles, structural rigidity for the panel is obtained in both directions, similar to plywood but with thicker components. In this way, the panel has great tensile and compressive strength.

CLT is claimed to consume only 50% of the energy required to produce concrete and a mere 1% of that needed to produce steel.
Prefabricated panels can be delivered to site as they are needed, making this construction method ideal for schemes with limited on-site storage capacity. They are then lifted into place, using pre-installed lifting straps, and rapidly assembled, greatly reducing construction time and therefore cost.
It’s a sustainable material because it’s composed of wood, a renewable resource (usually from reforestation), and doesn’t require the burning of fossil fuels during its production. CLT buildings are gaining traction, as they are often cheaper, quicker, cleaner and quieter to build than traditional structures.
The panels can function as walls, floors, furniture, ceilings, and roofs; CLT’s thickness and length can be adaptable to the demands of each project.

• As a renewable material, stores carbon throughout its usable lifespan
• Avoids thermal bridging (in parapet walls or flat roof solutions)
• Good delivery of airtight envelope
• Greater load distribution can reduce thickness of transfer slabs
• Simple and fast onsite construction process
• Vapour-permeable wall construction

• Requires completed designs ahead of start on site, to allow for offsite manufacture
• Use limited to above damp-proof course or equivalent level
• Requires accurately set out groundworks
• Requires external cladding or render to provide weatherproof envelope

CLT panels should be protected from moisture during construction and allowed to sufficiently dry before the application of linings. This includes adequate protection from rain and ground water on site. High initial moisture content of the timber elements — through exposure to weather during construction — creates a potential for interstitial condensation.
An air barrier, like Wraptite, should be installed on the outside face of the panels. The boards within the panels are not edge-glued, and therefore without this air barrier, leakage may occur.

Combining vapour permeability and airtightness in a self-adhering membrane, Wraptite offers a fast and effective solution to unplanned air leakage and its detrimental effects on energy performance. Wraptite not only ensures an airtight seal but resistance at laps against water penetration, dust, air infiltration and wind resistance making it an ideal choice for this application.