Learn · Building Science

Blower Door Testing

A fan in the doorway that turns “this house feels leaky” into a number you can act on — before you spend on equipment.

By Billy Gregus, Owner · Last updated July 2026

The Short Answer

A blower door depressurizes (or pressurizes) your home with a calibrated fan so we can measure how much air leaks through the building envelope. The result — often reported as ACH50 — shows how tight the house is and where smoke or infrared scanning can find the worst leaks. Premium customers use it to stop guessing.

What the test does

We seal a powerful fan into an exterior doorway, run the house to a standard pressure (commonly 50 Pascals), and measure airflow. That airflow converts into a leakage rate — how many times the house’s air volume would exchange per hour at that pressure (ACH50).

During the test, technicians can walk the home with smoke pencils or thermal tools to see attic bypasses, recessed-light leaks, garage connections, and other paths outdoor air uses to get in.

When blower door testing is worth it

Before a major HVAC replacement on a custom or older home.
When humidity problems persist after a “new” system install.
When you are investing in envelope upgrades and want before/after proof.
When comfort complaints do not match the thermostat reading.

How it pairs with HVAC design

Blower door numbers feed better load calculations and better conversations about ducts, returns, and ventilation. If the envelope is very leaky, throwing SEER2 points at the problem will not feel like the brochure.

Integrity’s analytical team uses diagnostics like this so solutions match the house — infiltration, duct design, dehumidification, and equipment selection in one plan — the level of work most companies never offer.

What it is not

Not a sales gimmick to force insulation upsells you do not need.
Not a substitute for Manual J / Manual D — it informs them.
Not only for new construction; existing Polk County homes benefit too.

Premium building-science work is what separates a comfort plan from a parts swap. Integrity's engineering-minded team diagnoses Winter Haven homes from every angle — envelope, ducts, humidity, and fresh air — then designs the fix.

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FAQ

Common Questions Answered

How long does a blower door test take?

Most residential tests fit in a scheduled diagnostic visit, often alongside duct inspection. Exact time depends on home size and whether we are also mapping leak locations for a repair plan.

Will the test damage my home?

No. The fan runs at controlled pressures used industry-wide. We protect finishes, and we do not “blast” the house. You may feel air at gaps — that is the point of finding them.

What is a good ACH50 for Florida?

Tighter is generally better for humidity control, but targets depend on home age, code path, and whether mechanical ventilation is installed. We explain your number in plain English and what improvements would actually change comfort — not chase a vanity score.

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