Air sealing reduces cracks and gaps in the building envelope. The Department of Energy says it's the most effective way to conserve energy.
Air sealing reduces cracks and gaps in the building envelope. The Department of Energy says it's the most effective way to conserve energy.

The Energy Freaks, as Sir Home Improvement calls them, are company technicians who conduct blower door testing to locate any holes in the building envelope. Air sealing is now something that the Kalamazoo, Mich., company does on every job, owner Frank Mumford says, checking 35 potential problem spots.

Air sealing involves locating cracks, gaps, and other openings, then sealing with caulk, foam, or Styrofoam. It can take a day, often less, but Mumford's is one of the few home improvement companies offering the service.

Air sealing is critical to home efficiency and adds to the services that companies can offer to improve a home's comfort and performance, says Bill Robinson, a one-time contractor who now teaches and trains on many specialties, including air sealing. If window companies sell their product by promising to improve home energy performance, Robinson says, imagine how receptive homeowners will be when contractors tell them, “We can air seal the rest of the envelope.”

HOW IT WORKS Once the number of air changes has been established by a blower-door test, technicians such as Hubie van Meurs, a Building Performance Institute-certified building analyst (and envelope specialist) for Alure Home Improvement, on Long Island, N.Y., find those leaks by “visual inspection, smoke pencils, and infrared cameras.” Alure's technician then presents homeowners with a “comprehensive assessment” of home-performance needs. What the air sealing portion of that costs depends on the condition of the building envelope.

Air sealing is typically done in conjunction with adding insulation where needed. That's for two reasons: Insulating without air sealing is of limited effectiveness, van Meurs points out; and sealing for leaks is much easier to do before insulation is installed.

MOST EFFICIENT According to the Department of Energy, air sealing is “often the most effective way to improve energy efficiency and comfort.” Van Meurs says Alure's before-and-after testing shows that homes can achieve a 15% to 40% savings in heating costs, and similar for cooling costs, depending on how efficient the house is when retrofitted. In Michigan, Mumford is steadily expanding his home-performance presence. “In the next decade, this is where it's at,” he says. “Anything that can save you energy, we want to be involved in it.”