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Blower Door Testing Services

Marathon Services is experienced in performing the Blower Door Tests in the Washington Metropolitan Area (DC–VA–MD–WV).  The Blower Door is the instrument used to measure the tightness of the building envelope. It is a powerful fan that is installed in a door opening, and it is used to evacuate air from the house.  We have used the results from this test to help countless homeowners, architects, business owners, and builders improve the energy performance of their buildings.

During the Blower Door Test, we look for areas where air is infiltrating using a smoke generator and the infrared camera. Common infiltration points are around doors, windows, light fixtures, and electrical outlets. Most homes also have leaks through other significant paths such as baseboards, plumbing and chimney chases, air ducts, attic access hatches, rim joists and band joists, knee walls, overhangs, and junctions between walls, floors, and ceilings.

Air sealing is a critical step towards improving the comfort and energy efficiency of any building, and must be performed before any additional insulation is considered. Generally, the measures to reduce uncontrolled air leakage can be performed very effectively and economically, and usually pay for themselves in a short period of time, in the form of lower energy bills.

Preparing for a Blower Door Test:

Take the following steps to prepare your residence or commercial building for a blower door test:

  • Close windows and open interior doors
  • Turn down the thermostats on heaters and water heaters
  • Cover ashes in wood stoves and fireplaces with damp newspapers
  • Shut fireplace dampers, fireplace doors and wood stove air intakes
  • Restrict pets to a safe and secure location