Blower Door Testing: Measuring Airtightness

Air leakage is responsible for 25-40% of heating and cooling costs in typical homes. A blower door test measures exactly how leaky (or tight) a home is, giving you a concrete number to work with.

How It Works

A blower door is a powerful fan that mounts in an exterior doorway. It depressurizes the house to a standardized pressure (50 Pascals), then measures how much air flows through the fan to maintain that pressure.

More air flow = more leakage. Less air flow = tighter house.

Understanding ACH50

ACH50 (Air Changes per Hour at 50 Pascals) is the standard metric. It tells you how many times per hour the entire volume of air in your home would be replaced through leaks at the test pressure.

• 7+ ACH50: Older/leaky homes
• 5-7 ACH50: Code-minimum new construction
• 3-5 ACH50: Better-than-code wood frame
• 1-3 ACH50: High-performance construction
• <1 ACH50: Exceptional (Passive House level)

Why ICF Tests So Well

ICF's exceptional airtightness comes from:

• Solid concrete walls: No gaps, cracks, or penetrations through the main envelope
• Continuous foam: Acts as an air barrier on both sides
• Fewer penetrations: Electrical and plumbing typically run in interior walls
• Quality installation: ICF construction requires attention to detail that benefits air sealing

Why Airtightness Matters

Energy: Every ACH50 point represents real energy dollars. Tighter = lower bills.

Comfort: Drafts disappear. Temperatures stay consistent room to room.

Indoor Air Quality: With controlled ventilation (ERV systems), you filter incoming air instead of breathing whatever leaks in.

Moisture Control: Humid outdoor air can't infiltrate walls and cause condensation or mold.

Our Testing Process

Every home we build is blower door tested—typically twice:

• Pre-drywall: Test and fix any issues while walls are accessible
• Final: Verify performance of completed home

We're not afraid to publish our numbers because ICF consistently delivers.