Spray cellulose helps make old home air tight
Like most houses built in the 1930s, Spillane was not surprised there was no insulation in any of the exterior walls. Only the attic had insulation, and it was probably added after the 1940s. Obviously, the house was not energy efficient and needed to be brought up to the city’s current energy code. Before any remodeling took place Spillane did a blower door test to determine the air tightness of the house. A powerful fan was mounted to the frame of an exterior door and the air was pulled out of the house, which lowered the air pressure inside. That allowed the higher, outside air pressure to flow into the house via the unsealed cracks and openings. The amount of air that leaked out of the house during this test is called the air infiltration rate. At the start of the remodel the rate was 9.5 per hour. The goal is to bring it down to 2 per hour or less. This can be accomplished by adding insulation and sealing all perforations to eliminate draft.
The city requires an R-19 insulation value in preexisting homes with 2’ x 4’ exterior walls, so Spillane opted to use spray cellulose. This is a seamless insulation system since it conforms to the house, will not settle, and fills the area so there are no gaps. Cellulose also will not rot, decay, or support fungus or mold growth. Spillane also took special care to close all perforations from one floor to another. Anywhere he drilled a hole or stud in the wall was filled with foam. He took extra precautions to eliminate duct work leaks to create a tighter air gap. When the house is complete, the blower door test will be repeated to see if the desired results were achieved.
Having passed both the city’s rough framing and insulation inspections, Spillane will now begin hanging drywall in the basement.