Blower Door Testing is Mandatory in Texas
The 2018 IECC, adopted statewide in Texas, requires a post-construction blower door test to verify air leakage.
Texas does NOT allow a visual inspection as an alternative. Texas requires a blower door test for all new homes.
| Climate Zone | Maximum Air Leakage (ACH50) |
|---|---|
| Zone 2 (Southern TX) | ≤5 ACH50 |
| Zone 3 (Central TX) | ≤5 ACH50 |
| Zone 4 (Northern TX) | ≤3 ACH50 |
– Homes in Houston, Austin, and San Antonio (Zone 2) must achieve ≤5 ACH50.
– Homes in Dallas-Fort Worth (Zone 3) must also achieve ≤5 ACH50.
– Homes in Amarillo and the Panhandle (Zone 4) must meet the stricter ≤3 ACH50 requirement.
How a Blower Door Test Works
A blower door is a specialized fan installed in an exterior doorway. It depressurizes the home to 50 Pascals (Pa), forcing outdoor air to enter through leaks in the building envelope.
✅ Equipment Used:
– Blower Door Fan – Creates pressure difference
– Pressure Gauge (Manometer) – Measures air leakage in Cubic Feet per Minute (CFM)
– Software Analysis – Converts CFM into Air Changes per Hour (ACH50)
✔ Formula to Calculate ACH50:
ACH = (CFM x 60) / Volume
Lower ACH values mean better airtightness.
How to Pass a Blower Door Test in Texas
✔ Seal air leaks around windows, doors, and wall penetrations.
✔ Install weatherstripping on doors and attic hatches.
✔ Use caulk and foam to seal gaps around plumbing, electrical, and HVAC penetrations.
✔ Ensure ductwork is properly sealed (duct leakage affects blower door results).
Need a Blower Door Test in Texas?
📞 888-213-3975 – Local Energy Audits – – Schedule a blower door test with a certified energy auditor today
A large house will leak at a higher CFM flow rate than a similarly constructed small house, simply because there is more surface area exposed to the exterior. Therefore, it is necessary to convert the blower door test results into a unit that is independent of house size.
The IRC/IECC sets a maximum Air Changes per Hour (ACH). ACH is the number of times each hour the full volume of air in the house is removed and replaced by outdoor air entering through leaks in the envelope.
ACH = (CFM x 60) / Volume
For compliance purposes, the 2018 IRC/IECC refers to the Air Changes per Hour (ACH) at the blower door test pressure of 50 pascals (rather than trying to estimate the leakage rate under natural house pressures).
The 2018 IRC/IECC specifies a maximum air leakage rate of 3 ACH in the TX Climate Zones.
