Since July 2017, the Florida Building Code was updated to require new residential homes to undergo a blower door test—and pass it. In Section 402.4.1.2, the blower test must have 7 air changes or fewer an hour. The Florida Building Code also specifies the “blower door testing shall occur after the rough in and after installation of penetrations of the building envelope, including penetrations for utilities, plumbing, electrical, ventilation and combustion appliances.”

How A Blower Door Test Works

A blower door is a type of fan that pulls air out from the inside of the home, causing the pressure in the home to drop. If air is able to re-infiltrate your home during the blower door testing, it will affect the air pressure in your home, which will be indicated on the calibrator on the blower door fan.

To prepare for the blower door test, following steps are taken:

  1. All exterior doors, windows, and fireplace will be closed (not sealed).
  2. Exterior ventilation systems are closed.
  3. Dampers, including the exhaust, intake, flue, and backdraft dampers, are closed.
  4. Interior doors are opened up.
  5. HVAC systems are turned off, but the ducts and supply and return registers are not sealed.

Then, the blower door is installed and the process to remove the air and monitor the air pressure begins.

How To Pass A Blower Door Test

According to the Florida Building Code, the readings during a blower door test cannot change over 7 times per hour in Climate Zones 1 and 2 or more than three times per hour in Climate Zones 3 through 8.

To help ensure the home you are building passes its blower door test, here are a few things you can do or make sure are present.

  • If there is a fireplace, it must have an air barrier.
  • The HVAC register boots must be sealed to the drywall or subfloor if they penetrate the building envelope.
  • Common walls between dwellings must have an air barrier installation.
  • If your exterior wall has an electrical or phone box, you can either ensure the existing air barrier goes beyond the box or the boxes need to be air sealed.
  • A shower (or tub) installed on an exterior wall must have an air barrier between the exterior wall and the fixture.
  • All the wiring and plumbing in your home need to have some type of insulation.
  • Any recessed lighting fixtures not installed in a conditioned space will need to be sealed to the drywall and have an IC (Insulation Contact) rating.
  • Air sealing needs to be present between conditioned spaces and the garage.
  • If the home has any narrow cavities, it must have the blown, spray, or batts insulation.
  • Penetrations and shafts around an unconditioned or exterior space must be sealed.
  • Crawls spaces are required to have a permanent insulation and any overlapping joints need to be taped up.
  • Also, if there is exposed ground around the crawl space, then it needs to have a Class 1 vapor retarder.
  • Flooring must have insulation that makes contact with the subfloors decking and exposed edges require an air barrier.
  • Rim joists need to be insulated and have an air barrier.
  • The space between the frame and door jamb or frame to window must be sealed.
  • The foundation junction and sill plate are required to be sealed.
  • All headers and corners of a wall must have insulation.
  • Knee wall doors, drop down stairs and attics (with exception of unvented attics) must be sealed.
  • Drop ceilings and soffits need an air barrier in line with the insulation and if there are gaps, then they must be sealed.
  • Air permeable insulation cannot seal but could be used inside an air barrier.
  • Exterior thermal envelop insulation used for the building envelope air barrier or for any of the frame walls must be aligned and in contact.

Blower Door Testing Company In Tampa Bay

AcuSytem Inspections offers over a dozen inspections for private residences and commercial properties. Blower door testing and new construction inspections are two of our many services we provide to builders and residents of Tampa Bay and surrounding counties. Contact us today to schedule a blower door test you are building—or an older home you own or are buying—to see how airtight and energy efficient your home is.