Spray foam seal

The builders used a fog machine, borrowed from a DJ who uses it in his gigs, to test how air-tight the home was. The test was done during a blower door test, which pulls air through a fan to exaggerate leaks.

By watching where the fog escaped from the main building, the builders were able to find places that needed to be sealed. They did the same test in the basement to see how cold air could penetrate into the main house. After that test, they were able to fill the cracks on the floor with spray foam, creating a very tight building. The test showed there are only 0.6 air changes per hour, while many older homes can have several air changes per hour.