Home Improvement Interior Remodel Basement

4 Basement Subfloor Options

When you install a floor covering in a basement, a subfloor is a necessity. A basement subfloor is a layer that is built below the floor covering (carpeting, laminate, etc.) and above the bottom, often concrete. A subfloor keeps moisture in check and inserts a thermal break to control temperates.

Learn the advantages and disadvantages of basement subfloors, including sleeper systems, floating plywood, rigid foam, and premade subfloor systems.

Basement Being Finished With Sub-Flooring

Perry Mastrovito Design Pics / Getty Images

Basement Subfloor

A basement subfloor consists of one or more layers inserted between a basement's top-most floor covering and bottom-most base floor to control moisture and temperatures.

Basement Subfloor Considerations

  • Moisture: Water can invade your basement or water vapor can gradually work its way upward through concrete basement flooring and condense. At least 60-percent of basements have moisture problems.
  • Temperatures: Basements are typically colder than grade-level floors. A subfloor breaks the thermal link between icy base floors and top floor coverings.
  • Height: Basements tend to be low, so even an inch or two in elevation for the subfloor will make a noticeable difference.
  • Installation: When installing your own subfloor, ease of installation is important. Premade subfloor systems are the easiest subfloors to build.
  • Cost: The cost of a basement subfloor mounts quickly when you're installing across the entire basement, so it's important to keep costs reasonable.

Sleeper System Subfloor

Layers Material*
Top Floor covering
Middle 1 Plywood fastened to the sleepers below
Middle 2 Two-by-four sleepers installed on-center every 12 to 16 inches and fastened down
Middle 3 Rigid foam insulation 1-1/2-inch thick placed between the sleepers
Middle 4 Vapor retarder
Bottom Concrete basement floor

Building a basement sleeper subfloor from two-by-fours topped with plywood is a traditional method that still works today, provided that your basement height affords enough space. One advantage of the sleeper system is that costs are kept to a bare minimum.

On the downside, height is a problem, as the sleepers are usually made out of two-by-fours. Two-by-fours are 3-1/2 inches wide (or in this case, tall). The plywood topping the two-by-fours and the top floor covering add even more height.

*Note: From top to bottom, this list of materials is shown in the same order that you would visually see these materials in a cross-section.

Tip

The vapor retarder is 10 or 15 mil sheeting of the type found at home centers or hardware stores. Plywood is 1/2-inch exterior grade kiln-dried plywood.

Floating Plywood Subfloor

Layers Material
Top Finish flooring
Middle 1 Plywood
Middle 2 Vapor retarder
Bottom Concrete basement floor

A floating floor is a floor that is not attached to the lower layer that it is resting on. The immense weight of the floor and the friction between the floor and the subfloor are enough to hold the floating floor in place.

As the least-expensive subflooring option, floating plywood's only barrier between the concrete and the plywood is plastic sheeting. The advantage of this type of basement subfloor is that it is thin and easy to install. Air and water cannot flow underneath this type of basement subfloor.

Rigid Foam Insulation Subfloor

Layers Material
Top Finish flooring
Middle 1 Plywood screwed down through the layer below
Middle 2 Rigid foam insulation—1-1/2-inch thick
Bottom Concrete basement floor

Rigid foam is an excellent basement subfloor option because it provides a thermal break between concrete and flooring. The materials also are easily accessible since nearly every home center carries rigid foam insulation in large, 4-foot by 8-foot sizes and up to 1-1/2 inches thick.

A rigid foam basement subfloor is a fast, cost-effective way to create a subfloor. The downside is that, like floating plywood, it does not permit air or water to flow underneath.

Premade Subfloor Systems

Layers Material
Top Finish flooring
Middle Subfloor module (Brands such as Barricade, Subflor, etc.)
Bottom Concrete basement floor

Subfloor systems eliminate the multi-layer approach of the do-it-yourself systems, giving you all of the layers fused into tiles or panels. These tiles are easily attached to each other and the subfloor goes down fast. The downside: the significantly higher price. The overall cost of the subfloor system can easily match or exceed the cost of the finish flooring, depending on the flooring that you choose.

Barricade is one such brand of premade subfloor system: 2-foot by 2-foot by 1-1/8-inch tiles with OSB wood on top and closed-cell polystyrene insulation on the bottom. The chief advantage of subfloor systems is the thinness of the product.

Tyroc is another such brand of premade subfloor panels. Coverage per panel is 5.3 square feet, with each panel measuring out at 48 inches by 16 inches. Tyroc claims that it has the thinnest profile of any other product in its category.

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  1. Winters, Brad et al. Report for the Urban Flooding Awareness ActIllinois Department of Natural Resources, 2015.