You ran the blower door. You failed. Now you’re behind schedule, wasting time, and throwing money at a problem that won’t go away.
Here’s exactly why you failed and how to fix it fast so you pass on the next test and move on.
Why Did You Fail Your Blower Door Test?
Because your building is leaking air—more than you thought. If you’re failing, it’s not just one spot. It’s multiple problem areas adding up, and something in your process isn’t working.
Most Common Air Leak Offenders
- Bottom plate to subfloor connections – Framing gaps on uneven concrete or wood expansion over time.
- Duct and plumbing penetrations – Poorly sealed openings where mechanicals pass through walls, floors, and ceilings.
- Electrical panel and wiring – A major leakage point that gets overlooked.
- Attic hatches, can lights, and bath fans – Big weak spots that we assume are fine but usually aren’t.
- Dead spaces behind tubs and fireplaces – Framing shortcuts leave major air gaps.
- Window and door casings – Small leaks that add up fast.
- Trades cutting through your air barrier – Most trades are not thinking about maintaining your air barrier; drywallers, electricians, and plumbers may not know about your blower door test. If they punch through a sealed area for an outlet, fan, or pipe, your airtightness is shot.
Even small leaks can add up. The more areas you can identify and seal, the better your chances of passing.
How Do You Fix a Failed Blower Door Test?
First, find the leaks. Then, seal them the right way.
Best Methods to Find Leaks Before a Retest
- Blower door test with an infrared camera – The most accurate way to pinpoint leaks.
- Smoke pen test – Low-cost but effective for visualizing airflow.
- Hand check – Feel for air movement when the building is depressurized.
Once you know where the leaks are, sealing them correctly is everything.
Best Way to Seal Leaks Before a Blower Door Test
If you’re still failing after multiple rounds of sealing, you’re probably making these mistakes.
- Using caulk for large gaps – Works for cracks but fails on bigger openings.
- Applying spray foam wrong – If you don’t cover the full gap, leaks remain.
- Over-relying on tape – Tape doesn’t create an airtight seal on all surfaces.
- Forgetting to check after sealing – Always verify corrective actions before calling for another test.
How to Fix It Right
- Use the right materials – Foam for larger gaps, caulk for small ones.
- Seal in layers – Don’t just rely on pre-drywall sealing.
- Verify before retesting – Double-check your work before wasting another blower door test.
How to Pass a Blower Door Test After Failing
If you’ve already failed once, the worst thing you can do is keep guessing. Most builders spend four or five rounds sealing and retesting, burning time and money. This is known as chasing CFM.
Why Manual Sealing and Retesting Often Fails
- Every house is different – Even pros can miss hidden leaks.
- It’s inefficient – No matter how careful you are, manual sealing leaves gaps.
- It’s time-consuming – Every extra test puts you further behind schedule.
If you want to stop failing and actually pass, there’s a better way.
AeroBarrier® is the Fastest Way to Pass a Blower Door Test
Instead of sealing, testing, failing, and repeating, AeroBarrier gets it done in one step.
How AeroBarrier Works
AeroBarrier is an automated, pressurized air sealing system that finds and seals leaks in real time. Sprayer units distribute a nontoxic sealant mist into the pressurized space, and as air escapes through leaks, the particles bond to the edges and close the gaps. The entire process is controlled and verified in real time using a blower door and proprietary software, ensuring you hit your ACH target. Once complete, a final report confirms the results, and construction can resume within 30 minutes.
Fix It Right. Pass the First Time. Stay on Schedule.
If you’re tired of sealing by hand, failing tests, and burning time on rework, AeroBarrier is the only solution that guarantees results.
Learn more about AeroBarrier and stop failing blower door tests.
