Once the closed cell foam was applied the house should be tight, so we could do a blower door test.
The front door is blocked and a fan in installed. The fan sucks the air out of the house to a difference the house pressure at negative 50 Pascal. Pascal is a measure of pressure. A typical existing home might leak at the rate of 15 air changes per hour at 50 pascal. Our test It came out 780 CFM at 50 Pascal or 1.0 ACH50. That’s 1 air change an hour at a negative 50 Pascal. That’s tight, but……I was hopping to get it lower, a 0.5.
To achieve a Passive House rating 0.7 ACH50 is the target. I’m not shooting for a Passive House certificate but I’d like to get to a 0.5 ACH50. But most Passive Houses are box on box construction. My house is far from a box on box. In going over the house it was easy to see how all the roof lines make it extra hard to seal the house as if it were a box on box.
Finding leaks is more art than science. The fan is reversed, pressuring the house. We then look at likely places for leaks hold a smoke wand in the area looking at how the smoke behaves. We found some small ones but no big holes. We are going to do some research and give it another try before the cellulous is installed.