After our last blower door test, the builder found and fixed a significant leak hidden behind one of the beams. Hopefully, that was the last one, as the airtight membrane is now inaccessible behind the drywall (gypsum board, sheetrock) in the ceiling. Before mounting the drywall on the straw panels, the wood beams are furred out a bit so that any straw sticking out doesn’t cause the boards to warp. We’re also using 5/8" drywall everywhere to keep it as straight as possible (also improves sound proofing).

We ran a second blower door test after sealing up a bunch of leaks. The result was a lot better: we got down to 1.1 ACH50 (air changes per hour at 50 pascals): a big improvement from 1.6, but not up to the passive house standard of 0.6. Before the test We sealed off all the drains with plastic sheeting and duct tape. The front door was much better adjusted, and also got taped on the outside.

As explained in a previous post, making the house airtight is crucial to passive house: air lost is energy lost. As well as a loss in comfort, air quality, and confidence that the house will perform as calculated. A blower door test is used to determine how airtight the house is. After a fan is mounted in a doorway, the house is depressurized by 50 pascals, and the airflow is measured.