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How to Maximize the Impact of Insulation

Ask This Old House general contractor Tom Silva shares some tips for insulating an attic.

Steps for Improving Home Insulation

  1. An easy way to improve the insulation in a home is by insulating the attic floor.
  2. Fiberglass insulation can be unrolled and placed into floor joists. Be sure to install unfaced insulation. Faced insulation has a vapor barrier that can hold onto moisture and cause mold in the attic floor and the ceiling below.
  3. It’s possible to rent an insulation blower and buy cellulose insulation to blow into the floor joists. In this case, blow the insulation so that it falls higher than the floor joists to allow for settlement.
  4. If the attic floor is covered, add a layer of rigid foam and then add ¼” plywood on top of that.


Tom demonstrated a variety of different insulation types that can be used in an attic. The fiberglass insulation Tom showed is manufactured by Owens Corning.

It comes in a variety of different R-values depending on where you are in the country and how much insulation you need, and it can come either faced or unfaced. Tom recommends getting unfaced insulation, but if it’s only available faced, you can peel the label off and use it.

Tom also discusses using cellulose insulation or using rigid foam insulation over floorboards to allow for storage and added insulation in an attic.