Blower Door Air Leakage Testing for Builders in Raleigh & Wake County
NC code air leakage testing (blower door) for new residential construction — the testing option under Section R402.4.2 (Air Sealing). Results reported as ACH50 or CFM50/SF per Section R402.4.2.2. Fast scheduling, same-day results.Every new home in North Carolina must demonstrate building envelope tightness under the NC Energy Conservation Code. A blower door test provides a measurable, code-compliant result. We conduct the testing, identify air leaks if needed, and provide clear documentation for inspectors.
What Is a Blower Door Test (Air Leakage Test)?
A blower door test — referred to in the NC Energy Conservation Code as an "air leakage test" under Section R402.4.2 (Air Sealing) — measures how tight a building's envelope is: how much outside air leaks in through cracks, penetrations, and construction gaps.Here's how it works: We install a calibrated fan assembly in an exterior door frame, then depressurize the house to -50 Pascals (Pa). The fan measures how much air flow (in cubic feet per minute, CFM50) is required to maintain that pressure. We then calculate the ACH50 value — air changes per hour at -50 Pa.
For example, if a 2,000 sq ft house has an ACH50 of 3, it means all the air in the house would be replaced by outside air 3 times per hour when depressurized to -50 Pa. Lower numbers mean tighter construction.
The 2018 NC Energy Conservation Code requires new homes to achieve ≤5 ACH50 or ≤0.30 CFM50/SFSA. The tighter the envelope, the less HVAC work is needed to condition the home, the lower the energy bills, and the less air drafting the homeowners experience.
NC Code: Air Sealing & Air Leakage Requirements
The 2018 NC Energy Conservation Code (NCECC) Section R402.4.2 (Air Sealing) requires every new home to pass a building envelope tightness test. Section R402.4.2.2 is the "testing option" — a blower door air leakage test at -50 Pa. Wake County is Climate Zone 4A and Johnston County is Climate Zone 3A — both require ≤5 ACH50 or ≤0.30 CFM50/SFSA.with calibrated equipment blower-door-fan-doorway-setup.webp • 800×533px • WebP quality 80 • Target: 50–80KB
Our Blower Door Testing Process
We follow ASTM E779/E1827 standards. The process is straightforward and typically takes 60–90 minutes from start to finish.Confirm House Ready
Before scheduling, the general contractor should confirm the house is ready for testing. The following must be complete:
- All exterior doors installed with weatherstripping and doorknobs in place
- All windows installed and locked
- Attic access closed and tight
- Crawl space access closed
- All exhaust fans fully ducted to the exterior
- HVAC equipment sealed and installed
Install Blower Door Fan
We install a calibrated fan frame in an exterior door (usually a back door). The setup is temporary and non-damaging.
Depressurize to -50 Pa
We run the fan and gradually increase negative pressure until we reach -50 Pascals. A manometer shows the pressure in real time. We make sure the pressure is stable and accurate.
Measure CFM50 & Calculate ACH50
At -50 Pa, the fan measures air flow in cubic feet per minute (CFM50). We record this value and divide by the house volume to calculate ACH50 — the number that determines pass/fail against NC code.
Generate Report & Collect Payment
We leave the completed report on-site at the time of testing, showing ACH50, CFM50, house volume, and pass/fail status. The NC Energy Efficiency Certificate is placed in the cabinet door under the kitchen sink. We scan all documents — PDF copies can be emailed to the inspector or contractor on request. Payment is due at time of service — we accept Zelle, Venmo, check, or cash.
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What If Your House Fails the Blower Door Test?
If ACH50 exceeds 5 (the NC code limit), the house fails. But we don't stop at the number — we help you identify where the leaks are and fix them quickly.When we test, we bring diagnostic tools. If a house fails, we use a smoke pencil (handheld smoke pen) or thermal imaging camera to find the leak points. We then provide a detailed report pinpointing the problem areas. Common failure points include:
Recessed cans in ceilings are notorious air leaks if not IC-rated and sealed
Holes in exterior walls around outlets need gaskets behind face plates
Foam sealing around frames and weatherstripping gaps
Where walls meet roof or upper stories — needs caulk and gaskets
Pipe, wire, and duct penetrations through the building envelope need to be fully sealed with caulk or foam
Pull-down stair hatches and scuttle openings are common leak points — need weatherstripping and a tight seal
Once identified, these areas are sealed (caulk, foam, gaskets, or tape). The builder can then schedule a retest. Most houses pass on the second test after simple air sealing.
Why Builders Choose Peak Energy for Blower Door Testing
We understand new construction schedules. Fast scheduling, clear pass/fail results, and on-site leak identification if needed — we make compliance easy.Blower Door Testing for Contractors vs. Homeowners
This page is for builders and contractors managing new construction. For existing homeowners seeking home energy audits, we offer a different service.Blower door testing serves two distinct purposes:
| Aspect | New Construction (This Service) | Existing Home Energy Audit |
|---|---|---|
| Purpose | NC code compliance verification | Diagnostic tool to identify energy losses |
| Audience | Builders, contractors, developers | Homeowners seeking efficiency improvements |
| Timing | After rough-in and before final occupancy | Any time, ongoing diagnostics |
| Includes | Blower door test only, leak identification if failed | Blower door + thermal imaging + duct testing + moisture assessment |
| Goal | Pass/fail against 5 ACH50 standard | Identify where to invest in energy savings |
| Report Use | Building inspector compliance | Homeowner improvement planning |
If you're a homeowner looking to improve energy efficiency in your existing home, our home energy audit service includes blower door testing as one diagnostic tool. For new construction code compliance, this is the right page.
Frequently Asked Questions
How much does blower door testing cost?
Blower door testing is $250 per test. A travel fee may apply depending on location. The fee includes the test and a completed report left on-site at the time of testing.
What is the NC code requirement?
The 2018 NC Energy Conservation Code (NCECC) requires new residential construction to achieve ≤5 ACH50 or ≤0.30 CFM50/SFSA (Section R402.4.2.2), tested at -50 Pascals. Testing must occur after rough-in and envelope completion, and again before final occupancy. Results must be documented and available for inspector review.
What if the house fails the blower door test?
If ACH50 exceeds 5, the house fails and cannot receive final occupancy until air sealing is completed. We identify leak locations using smoke pencils or thermal imaging and provide a detailed report with recommendations. Common fixes include sealing rim joists, recessed lights, roof penetrations, and electrical outlets. After sealing, the house must be retested and pass.
Can I do a blower door test at rough-in and then again before final?
Absolutely. Many builders request rough-in testing to catch leaks before drywall installation (cheaper and easier to fix). We can schedule both tests and provide separate reports. The final test before occupancy confirms compliance with NC code.
How long does the test take?
Typically 60–90 minutes, depending on house size and complexity. We install the blower door fan, depressurize to -50 Pa, record the CFM50 measurement, calculate ACH50, and leave the completed report on-site.
What format is the report, and how soon will I have it?
We leave the completed report on-site at the time of testing, showing the ACH50 value, CFM50 reading, house volume, and pass/fail status. The NC Energy Efficiency Certificate is placed in the cabinet door under the kitchen sink. We scan all documents and can email PDF copies to the inspector or contractor on request.
What payment methods do you accept?
Payment is due at time of service. We accept Zelle, Venmo, check, or cash. Contractors with a pre-approved account may be set up for invoiced billing — contact us to arrange.
Schedule Your Blower Door Test
Serving Holly Springs, Raleigh, Cary, Apex, Fuquay-Varina, and the Triangle area. NC code compliance testing, fast reporting, same-day results.
Schedule a TestOr call (919) 567-5329