|Is My Home Airtight?
One of the least understood aspects of home construction is what it takes
to make a home substantially Airtight.
A blowerdoor is used to test Airtightness. But what do the numbers mean and
how do you make your home Airtight?
Air Changes per Hour (ACH)
The blowerdoor yields the number of Air Changes per Hour (ACH) at a standard
test pressure. In simple terms, the test simulates a 15 mph wind on all sides
of the home. The lower the number, the tighter the house (and the better
we can control the comfort and air quality inside the house).
Many existing houses have 10 or more ACHs. To meet NYS Code, a home must
have less than 7 ACH. Energy Star homes have to have less than 5, and starting
in 2012, less than 4 ACH. To qualify as a Passive House, a home has to be
less than 0.6 ACH. Those are tight houses!
How do you make your home Airtight?
There are several approaches to make a home Airtight. The building code has
a prescription for conventional homes. The list of prescriptive requirements
is shown below.
Some construction techniques and insulation systems lend themselves to making
a home tighter. Cellulose insulation, for example, will generally yield
a tighter home than fiberglass batt insulation. Adding membranes and
board insulation to the outside of a home can greatly improve the Airtightness
If you need more help making your home Airtight, please give us a call!