How to Install Insulation in Your Floors Without Tearing Up the Floors

Adding insulation beneath your flooring will result in increased comfort and reduced heating bills. Depending on what kind of foundation your home sits on, your options for installing under-floor insulation without tearing up the floors are limited and straightforward. If it's a slab, your flooring will almost certainly need to come up, but if you have a basement or a dry crawl space, you can install insulation between the floor joists. There are a variety of insulation materials to choose from, including spray foam, loose-fill cellulose, and rigid foam board. The most flexible choice, however, is also the easiest to deal with: fiberglass batts.

Measuring tape
Safety glasses
Dust mask
Protective gloves
Unfaced fiberglass insulation batts
Utility knife
Insulation spring rods

Instructions

- 1
  Measure the internal depth of the joist cavity from the bottom edge of the joist to the subfloor surface at its top. Follow up by measuring the width of each cavity. For maximum R-value, select an unfaced fiberglass insulation batt of the appropriate width and a thickness at least one inch less than the cavity's depth.
- 2
  Add up the length of each joist cavity to determine how much insulation you will need.
- 3
  Don your gloves, dust mask and safety glasses when you are ready to start working with the insulation.
- 4
  Using the utility knife, cut the insulation batt to fit the measured length of the joist cavity.
- 5
  Start at one end of the joist and push the insulation gently into the cavity until it pushes against the top, rolling the insulation out until you reach the opposite wall. Take care not to compress the fiberglass, as this will reduce its insulating ability. Use the knife to cut and fit the insulation around any obstructions such as pipes, wires or bracing. Friction will hold the insulation in place temporarily.
- 6
  Install insulation spring rods about every 18 inches under the insulation along the entire length of the cavity. The rods are slightly longer than the cavity width and require a slight twist in order to mount to the joist. The rods will keep the insulation from sagging and slipping out of the joist cavity.
- 7
  Repeat Steps 4 through 6 in all remaining joist cavities until each has been filled.

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