Airtight (Everything is Alright)
11/04/2016 . News
We reached a major milestone on site at the Passivhaus we are helping Meloy Architects construct in Sussex. Following the installation of triple-glazed roof lights it was time to carry out a preliminary air test. All certified Passivhaus buildings must achieve an airtightness 0.6 air changes per hour at a pressure of 50 Pascals. Our experience has shown that it is a good idea to carry out an initial test once the main building envelope is completed, before the final finishes are installed. This allows any leaks in the airtightness layer to be identified and rectified without costly alterations.
Right: Martin Gill searches for potential sources of leaks in the airtightness layer with a simple smoke taper.
Charles Meloy had contacted Martin Gill of Tophouse Assessments to carry out the test. By the time we arrived on site Martin had already installed the door fan into the newly installed back door frame. The house was quickly pressurised to 50 pascals, pushing the Pro-Clima Intello membrane tight against the SIPS panel construction. The first results suggested that the air change rate was around 0.65. Using a simple smoking taper, we tracked down areas where the airtightness could be improved. We quickly established that one of the large sliding doors on the South elevation was slightly misaligned, and not compressing a gasket sufficiently.
Below: Charles Meloy checks the seal between the airtightness membrane and the triple-glazed roof lights in the pitched roof.
The door frame was temporarily sealed to exclude the leak from the investigations. A missing silicone seal on the corner window was also found to be contributing to the leakage. After further small defects in the sealing around the roof structure were dealt with Martin started the fan again. The final test result was a very satisfying 0.54 air changes per hour leaving Charles with a reasonable margin for error as he completes the services installations.