Plan Your Floor Insulation Project

Plan How to Upgrade Your Floor Insulation Project Carefully

Floor insulation within unconditioned spaces occurs in two basic ways:

  1. Within a closed floor cavity, or
  2. Within an open floor cavity.

Let’s review the standard applications.

    Blown-in Insulation in a Closed Floor Cavity

      To install floor insulation in an existing closed floor cavity without removing the interior or floor surfaces, you need loose-fill cellulose. You also need an insulation machine capable of dense-packing the insulation in the floor cavity. This step must completely fill the cavity and stop any air leakage between inside and outside of the floor. This process of blowing insulation into floor cavities under pressure is called “dense-packing”.

        To gain access to the floor cavities, drill holes into the interior sheetrock or plywood. For drilling holes into the exterior sheathing, remove the exterior siding and replace it after the insulation installation. (Unless homeowners install new siding upon completing the floor insulation.) For homes built before 1978 make sure all work complies with lead paint safe work practices. Also, some homes still contain asbestos siding, which homeowners must considered as part of any insulation project.

          Upgrading Your Floor Insulation when the Floor Joist Cavities are Open and Accessible

            If the home has open floor joist cavities such as those in the floor above a crawl space or basement, the insulation options differ. Next, insulate the open floor joist cavity with fiberglass batts that fills the entire framing cavity depth. Before insulating the floor joist cavity, completely air seal all gaps, holes and voids. This step helps improve comfort and minimize insect entry points. Upon air sealing, install the  fiberglass batt insulation in the floor system. GHA recommends filling the framing cavity with an R-38 or sufficient insulation level. Finally, install the insulation so it touches the plywood sub-flooring above it.

              As an alternative, two component or two part spray foam insulation can be used to insulate the floor cavity. Both open cell and closed cell spray foam offer good insulating and air sealing performance for homeowners.  However, since closed cell insulation offers a higher R-value per inch, it is the choice of most homeowners.

                As you can see, insulating floors can be challenging. It requires experience, special tools, powerful insulation machines and, in some cases, special training to work with surfaces contaminated with lead paint or asbestos. To get the best results, it is usually wise to hire an experienced contractor that is trained and equipped to complete this type of work. An experienced contractor can help you determine:

                    1. Are there any existing health or safety concerns to be considered as part of your floor insulation project?
                    2. What type of insulation would be best for your floor insulation project?
                    3. Will floor insulation help warm the floors of my home during the wintertime?

                A quality contractor helps determine the best approach for proper floor insulation installation. Once insulated, the floors in your home perform at a very high level offering maximum comfort with minimal energy cost.