Benefits of Basement Insulation

While every building needs a solid foundation, not every foundation is the same. Homes across the United States may be built on cement slabs, over crawlspaces or have full basements running beneath the first floor. Homes in the Midwest and Western U.S. are much more likely to have basements than those in the South and along the coast. The type of soil and water table level helps determine whether a basement is possible or not.

Basements come in many varieties, from fully conditioned spaces with finished floors, walls and ceilings to cement block or brick cellars with dirt floors. However, one thing they all have in common is their need for adequate basement insulation.

To enjoy the most comfortable home environment and conserve energy, homeowners should work to improve their home’s thermal envelope. Think of your home as a case built to keep the contents secure from outside elements. Each part of the case is equally important, as one weak area can spoil the whole setup. A poorly insulated basement can set the stage for an uncomfortable home environment. Likewise, a correctly insulated basement can make your home pleasant and snug — from the ground up.

Understanding R-Values

When your body comes in contact with something cold, like an ice cube, your body heat is transferred to the ice, melting it, and making your hands cold. When a warm basement wall meets cold soil, heat is lost in the same way. Insulation products are designed to help prevent this energy exchange. A product’s R-value refers to its ability to resist heat transfer. Higher R-values equal greater insulation properties — and less heat loss to the outside.

Insulating Basement Walls During Construction

Obviously, it’s easiest to insulate the basement, just like any area of the home during the initial construction. Contractors routinely use XPS foam board on the outside of exterior basement walls. These rigid boards, manufactured by extruding raw materials through a custom die, are extremely durable.

Owens Corning’s brand of XPS, FOAMULAR®, has a void-free cell structure thanks to the company’s unique manufacturing process. Research shows the boards hold their R-value even when exposed to water or wet soil, making them a reliable choice. FOAMULAR® isn’t just for contractors and new construction projects, though. Homeowners will find it offers a range of benefits for existing home projects.

Adding Insulation to an Existing Basement

There are many reasons to add insulation to an existing basement. Perhaps you’re unhappy with the comfort level of your home, want to create a finished TV or game room or just ensure you’re paying the lowest utility bills possible. Fortunately, you should be able to find what you need at home improvement stores. For expert advice, seek out basement insulation solutions from heating and cooling contractors.

XPS Foam Board for Basement Walls

Made from extruded polystyrene, foam boards can be added to the interior side of basement walls that will be finished. Although you can cut them to fit between studs, the 4 x 8 sheets are designed to cover the entire wall before framing takes place. This product’s ability to resist moisture makes it a perfect choice for cement or brick walls that may weep.

Pro Tip: Make sure the walls are dry before installation. If you have a continuous moisture problem, you should fix it first. Using a waterproofing product designed for masonry can help block the occasional moisture that may seep through the concrete blocks.

You can also use foam board for basement floor insulation before adding wood or vinyl flooring. Make sure you have enough clearance first, as local building codes may specify a minimum floor-to-ceiling height measurement.

Owens Corning’s FOAMULAR® has an R-value between 3 and 10 depending on the thickness and psi value.

Using Mineral Wool Insulation in Basements

Owens Corning mineral wool insulation products, known as Thermafiber®, offer several benefits to homeowners.

• Sustainable, made from ove70% recycled content
• Water-resistant
• Mold-resistant
• Easy to install
• Non-combustible

Because of its unique properties, mineral wool is another great choice for basement insulation. You can place it between wall studs or floor joists, as you would fiberglass. It’s easy to cut with a serrated knife, and its R-value rating ranges from 15 to 30.

Pro Tip: If you want a finished basement wall that’s mold- and mildew-free, start with XPS foam board, then add stud framing, mineral wool batts, drywall, and latex paint.

Fiberglass Insulation

You may be able to use fiberglass insulation in some areas of the basement. Fiberglass isn’t recommended for direct contact with brick or cement block due to moisture concerns. Fiberglass is sold in rolls or batts sized to fit between studs, both 2x4 and 2x6. Owens Corning’s PINK fiberglass is designed to fiction-fit, meaning the product will stay in place without slumping. You can staple the side flanges of the paper facing to the stud edges as well.

According to the Department of Energy, recommended R-values for basement walls range between 13 to 21 depending on the temperature zone. Owens Corning PINK fiberglass is available in R-values up to 49 and is sold with a kraft vapor retardant facing and without. If you decide on faced insulation, make sure you completely cover the facing to prevent a fire hazard.

You can use fiberglass for basement ceiling insulation — between the floor joists. Adding wire ties can help secure the insulation in place. Cover with a dropped ceiling.

Other Basement Insulation Considerations

While you’re working on your basement, take a moment to examine the heating and cooling ducts. Chances are you have a large network of ducts running from the furnace. Adding insulation to the exterior surface of these ducts can greatly improve the efficiency of your system.

Another possible source of heat loss is through cracks or openings in your basement walls. Make sure any protrusions are sealed, such as pipes leading to the condenser unit of your A/C system. Canned gun foam is a handy tool for these situations.

Insulation: Whole Home Concept

Remember the thermal envelope example. Improving your home’s basement insulation is just one segment in your journey towards total home energy efficiency. Take time to check out your walls, attic, air distribution system and flooring. Over the years, the benefits will pay out in a more comfortable home environment and lower heating and cooling costs.