Blower Door Test
NCI-certified blower door testing for code compliance, energy audits, and home comfort. 6-state service area since 2009.
NCI Certified
RESNET Certified
IBHS FORTIFIED
Since 2009
6-State Service
Fixed-Fee Quotes
A blower door test measures how airtight a building is. HECS runs residential and light-commercial blower door tests across Kentucky, Ohio, Indiana, Tennessee, Illinois, and Missouri. Every test is performed by an NCI-certified technician and delivered with a certified report your code official, HERS rater, or program reviewer can sign off on.
What is Blower Door Test?
A blower door test uses a calibrated fan mounted in an exterior doorway to pressurize (or depressurize) the building to a standard 50 Pascals of pressure difference relative to the outside. The fan’s airflow in cubic feet per minute (CFM) at 50 Pa is the building’s air leakage rate, expressed as CFM50 or ACH50 (air changes per hour at 50 Pa).
Lower numbers mean a tighter building. A typical 2,400 sq ft code-built home in 2026 tests around 3,000-4,500 CFM50. ENERGY STAR v3 homes target 1,500-2,500 CFM50. Passive House is below 0.6 ACH50. The test pinpoints where air leaks through the building envelope: around windows, doors, recessed lights, attic hatches, plumbing penetrations, and the rim joist.
HECS blower door tests follow RESNET Chapter 8 protocols and the 2015 / 2018 / 2021 IECC. We use Retrotec and The Energy Conservatory calibrated fans, and the test is typically combined with a duct leakage test for the most useful single-visit diagnostic.
Who needs blower door test?
-
Homebuyers commissioning a pre-purchase energy audit.
Builders needing code compliance for the 2015/2018/2021 IECC Section R402.4.1.2 (≤3 ACH50 in Climate Zone 4, ≤2 ACH50 in CZ 5, ≤1.5 ACH50 in CZ 6-8).
Code officials requiring third-party verification for sample-pass rate compliance.
HERS raters and program reviewers using blower door results to model energy use.
Homeowners chasing high-bill complaints, comfort problems, or moisture/IAQ issues.
HECS’s process for blower door test
- Pre-test walkthrough (15 min). HECS tech walks the home with the homeowner or GC, identifying operable windows, fireplace dampers, and known air-leakage suspects. We seal HVAC returns and the water heater combustion air so the test isolates envelope leakage only.
- Fan setup and depressurization (10 min). Fan mounts in the front door, speed controller set to 50 Pa, building depressurized. Multi-point test (CFM at 25 / 40 / 50 Pa) gives the leakage curve used for IECC compliance and HERS modeling.
- Leakage hunt (30-45 min). With the building depressurized, the tech uses a thermal camera and smoke pencil to find and log each major leak site: recessed lights, attic hatch, rim joist, window headers, plumbing penetrations.
- CFM50 and ACH50 calculation (5 min). From the multi-point data we calculate CFM50 (total leakage) and ACH50 (leakage per hour, normalized to building volume). Result is ready immediately.
- Certified report (delivered in 3-5 business days). Formatted for your reviewer — IECC code official, RESNET HERS rater, ENERGY STAR v3, NGBS Green, EarthCraft, FORTIFIED, or your lender.
Blower Door Test pricing (2026 benchmark)
| Project type | 2026 cost |
|---|---|
| Single family (≤2,500 sq ft) | $200 – $350 |
| Single family (2,500-4,500 sq ft) | $300 – $450 |
| Duplex / side-by-side | $400 – $600 |
| Multifamily (per building, 4+ units) | $600+ (per project, quoted on scope) |
| Combined blower door + duct leakage | Save $50-100 vs. separate visits |
Pricing is 2026 Midwest benchmark. Travel bundled with related services. Fixed-fee proposal within 24 hours of a free scoping call.
Service area
HECS runs blower door tests across six Midwest and Mid-South states: Kentucky, Ohio, Indiana, Tennessee, Illinois, and Missouri. Our Louisville KY headquarters covers KY; field teams run recurring routes to Cincinnati, Columbus, Indianapolis, Nashville, Chicago, St. Louis, and every other metro in the service area.
HECS also delivers blower door test in:
Blower Door Test — frequently asked questions
How long does a blower door test take?
About 1.5-2 hours on site for a typical single-family home, including setup, the test, and the leakage hunt.
Do I need to be home for the blower door test?
Yes — a homeowner or builder representative must be on site to grant access and unlock areas. The test is non-invasive but requires opening all interior doors and closets.
What’s the difference between ACH50 and CFM50?
CFM50 is the raw cubic-feet-per-minute leakage at 50 Pa. ACH50 normalizes that to the building volume, giving air changes per hour. Code officials use ACH50; HERS models use CFM50.
Can I fail a blower door test?
Blower door tests don’t pass/fail on their own — they measure. Code compliance is the threshold. A typical 2026 ENERGY STAR v3 home in Climate Zone 4 needs ≤3 ACH50; the 2018 IECC residential requirement is 3 ACH50 in CZ 4, 2.0 in CZ 5, 1.5 in CZ 6-8.
Will the test damage my home?
No. The fan is mounted in a doorway with a sealed frame. The building is depressurized briefly (5-10 minutes) to 50 Pa — about 1/200th of a hurricane-force pressure difference. Nothing in the home is altered.
Do you provide same-day results?
ACH50 and CFM50 are calculated on site and shared before we leave. The certified written report follows in 3-5 business days.
Related HECS services
Get a Blower Door Test proposal
Fixed-fee proposal within 24 hours — not an estimate.
Related HECS services: all HECS services · Contact HECS · HERS Rating · Blower Door Test · Duct Leakage Test · FORTIFIED Roof Evaluation