Learn About Floor Insulation Solutions

Generally, homeowners install floor insulation above unconditioned spaces in two general ways. The first method insulates the open floor cavities. For example, open cavities include floors above crawl spaces and basements. The second method insulates floors by drilling holes in the closed cavities. These cavities include floors  over garages or cantilevers. In this method, technicians blow-in insulation into these cavities and remains ideal for closed floor cavities. However, this technique requires experience with the use of insulation machines and the techniques for properly insulating a closed cavity.

Additionally, many different types of insulation exist for floor insulation projects. to help, the following offers a brief overview of the different insulation options. Plus, how these options insulate floors over unconditioned spaces of homes:

Fiberglass Insulation

Fiberglass Insulation. Primarily composed of glass and used as a thermal insulator. It slows the transfer of heat by trapping pockets of air to keep rooms warm in the winter and cool in the summer. Fiberglass rolls or batts help insulate floors over unconditioned spaces. Before insulating, however, the floor above the unheated space, all gaps, holes and voids need air sealing. This step improves comfort and minimizes insect entry points.

Upon air sealing, installation of the fiberglass batt insulation begins into the floor system. GHA recommends an R-38 or an insulation level sufficient to fill the framing cavity. Additionally, install the insulation so it touches the plywood sub-flooring above it with no gaps or air spaces. When installed correctly, fiberglass provides an R-Value of approximately 3.0 to 3.5 per inch.

Cellulose Insulation

Cellulose Insulation. Primarily made from recycled materials such as newspaper and cardboard. Typically, manufacturers treat cellulose with fire retardants and materials that repel insects and rodents. Cellulose only comes in loose-fill form and not available in a roll or batt for like fiberglass. However, cellulose remains ideal for floors above garages or in closed cantilevers on the front or back of homes. When dense-packed, cellulose offers resistant to air movement and provides an R-Value of approximately 3.2 to 3.5 per inch.

Spray Foam Insulation

Spray Foam Insulation. This insulation combines excellent air tightness and high insulation R-values into a single product. The basic types used to insulate and air seal today’s homes include one and two component spay foam.

One-component spray foam is best used as a sealant for small joints and cracks roughly the size of an inch or less. 1-part spray foam requires no hoses or large tanks to move around but it is not a good product to seal larger openings.

Two-component spray foam is ideal for filling voids and cavities in your home that are larger in nature. Since 2-part spray foam expands rapidly as soon as it leaves the applicator, insulating large sections of floors with open cavities are common uses for 2-part spray foam. Two component spay foam is also available in open cell and closed cell formulas. Open cell foam is lower density (1/2 lb per cubic foot) and has an R-value of 3.5 to 4.0 per inch. Closed cell foam is foam is higher density (2 lbs per cubic foot) and has an R-value of 6.0 to 7.0 per inch.

Regardless of the insulation type, R-value measures insulation performance. In fact, R-value measures heat flow resistance of insulation (or any material). The higher the R-value, the better the insulating capability. GreenHomes recommends a minimum of R-38 insulation for floor cavities (or the amount of insulation sufficient for filling the framing cavity).