Plan Your Basement Insulation Project Carefully
Basement insulation projects vary by basement type. For example, certain installations occur in the floor above the basement. Conversely, some installations occur in the foundation walls that enclose the basement. As a result, homeowners face a few important decisions.
First, before starting any insulation work, ensure the applicable surface remain dry and free from moisture contamination. For a successful insulation, ensure the surfaces contain no signs of moisture or mold on the foundation or wood surfaces. If moisture exists, eliminating the moisture problems remains the number one priority.
Basement Insulation For Semi-Conditioned Basements
For dry basements with a heating/cooling supply or semi-conditioned spaces, GHA recommends wall insulation. First, focus on the top of the foundation wall area (called the rim joist) because this area remains primarily exposed to the coldest outdoor temperatures in winter and the hottest outdoor air temperatures in summer. Typically, the rim joist is air sealed and insulated with spray foam or a combination of spray foam and batt insulation. Spray foam is excellent at sealing the many air gaps in the rim joist. Plus, cut-to-fit batt insulation helps raise the total R-Value (well above the R-20 minimum).
For many warmer climate zones, homeowners must leave an unobstructed 3” minimum termite inspection gap with no insulation between the bottom of the wood sill and the foundation wall. Upon proper insulation of the rim joist, then insulate the moisture-free basement wall with off the shelf basement insulation finishing systems, spray foam or foam board insulation. Remember that foam insulations must meet any fire code requirements in your area.
Basement Insulation For Unconditioned Basements
For dry basements with no heating/cooling supply or unconditioned basements, install insulation in the floor joists above the basement. Before insulating the floor above the basement, all gaps, holes and voids, homeowners must completely air seal. Why? Complete air sealing improves comfort and minimizes insect entry points. Only after air sealing, can insulation be installed in the floor system (to an R-38 or an insulation level sufficient to fill the framing cavity). The insulation must be installed so it is touching the plywood sub-flooring above it. In addition, ducts and heating pipes require sealing and insulation in unconditioned basements.
Selecting a Basement Insulation Specialist
Insulating basement spaces remains a challenging task. As discussed, based on your basement, homeowners possess several options as moisture problems remain a concern. And remember, basement insulation work remains extremely difficult and dangerous. As a result, 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 helps you determine:
- Any existing moisture problems, such as areas of excessive condensation, water leaks or mold! If so, resolve all moisture problems in the basement before insulating.
- Any health and safety problems in your basement such as mold, asbestos or electrical hazards!
- The best way to insulate the floor above the basement or the basement walls and why!
A quality contractor helps ensure all of the holes or connections between the house and the basement remain sealed. For example, experienced contractors inspect chimneys, plumbing piping, electrical wires, heating ducts and communication wires remain sealed properly, Additionally, reputable contractors confirm these spots contain the proper sealants, caulks, spray foams or air-tight boxes. Remember, air sealing in basements around chimneys and fire rated walls has to be done using methods and materials appropriate for higher temperatures. Experienced contractors contain the proper training.