SMARTPLY PROPASSIV is a structural OSB panel with integrated vapour control and air barrier properties for use as structural sheathing in timber frame structures. Airtightness is engineered into the OSB panel substrate, whilst SMARTPLY's in-house speciality surfacing technology provides an integrated vapour barrier with consistently high vapour resistance over the entire surface. SMARTPLY PROPASSIV meets all the requirements of EN 300 for the production of OSB3 panels and therefore can be installed as any other OSB3 panel.

To be recommended by the PHI, products must be tested according to uniform criteria and proven to be of excellent quality regarding energy efficiency. As part of the testing process by PHI, SMARTPLY supplied nine samples measuring 315 x 305 x 12.5 mm – each coated at the edges with a sealing compound to reduce the influence of the small board size. Measurement of the leakage volume flow took place at pressures between 300 and 1000 Pa in order to obtain sufficiently high flow rates, while both positive and negative pressure measurements were carried out.

“OSB is assumed to be airtight, but tests showed a huge variation in performance, between manufacturers and even between different production cycles,” explains David Murray, Innovation Manager at SMARTPLY. “Developed from our OSB3 system, SMARTPLY PROPASSIV has now been proven to achieve the highest levels of airtightness required to meet the Passive House Standard.”

Suitable for both new build and renovation projects, SMARTPLY PROPASSIV is a versatile, strong and cost-effective OSB panel system. And if the UK is to cut its carbon emissions in line with stringent building regulations, this latest OSB innovation will play a vital role as part of a highly sustainable and fabric first approach.