Blown in wall insulation for older homes

How dense pack works

We drill a small hole into each stud bay, run a fill tube in, and blow insulation until the cavity is packed full. Packed tight, it fills around wires and boxes and stays put instead of slumping. Then every hole gets plugged.

The Department of Energy calls drill and fill one common and somewhat uninvasive method for insulating existing walls [2], and says dense pack has the advantages of preventing insulation from settling, completely filling the cavities, consistent insulating values, and the ability to slow airflow [3].

Before we drill

• We check what is in the walls now. Some have a little old insulation, some have none.
• We look for anything that should not be buried. Old knob and tube wiring is one: ENERGY STAR lists it as a fire hazard when in contact with insulation and says to have a professional deal with it first [4], and the DOE notes the electrical code does not allow insulation to surround it [2]. If a wall has live knob and tube, we tell you before we drill.
• Blocking inside a wall can stop the fill partway, so we check for it.

Open walls are easier

On a new build or a gutted room, the walls are open, so they get fiberglass or rock wool batts, or spray foam. See new construction.

Who has empty walls

Across Franklin, Licking, Muskingum, Fairfield, Perry, Morgan, Hocking, Athens, Washington, Vinton, Meigs and Gallia counties, 238,217 of 891,006 homes were built before 1960, and 119,055 in 1939 or earlier [1]. In the older river and county seat towns the share runs much higher. See your county.