What You Need To Know About Insulated Subflooring

For homeowners looking to finish a basement, finding ways to keep your basement warm and dry should be a number one priority. Unfortunately, those concrete slabs that make up your basement floor are most likely a magnet for moisture. Simply putting a bit of plywood subflooring on top of that concrete slab will most likely leave you dealing with mold and mildew growth, warped flooring, and unbearably cool temperatures a few years later.

Relatively recently, several companies have begun to bring to market insulated subflooring options that make it quick and easy to insulate and waterproof your basement floor. This complete Rise guide will take an in-depth look at how to choose the best-insulated subflooring option for your basement.

In the past, many builders and DIY homeowners may have resorted to placing 2x4 sleeper boards between some plastic vapor barrier. This solution does work for waterproofing, though leakage in the bottom layer of the vapor barrier could cause rot issues with the 2x4 subflooring. Furthermore, it offers minimal help in terms of insulation for the basement.

Suppose you want to improve your basement's energy efficiency and thermal performance. In that case, you could also install rigid form insulation on top of the concrete slab with plywood screwed on top. The problem with this solution is that it is time-consuming in that it requires the installation of several separate layers and may also reduce the total height of your basement ceiling due to these layers.

Insulated subfloor panels, on the other hand, offer an easy-to-install and high-performance alternative that can simultaneously waterproof and insulate the concrete slab of your basement. Most companies manufacturing these insulated subflooring alternatives produce them as panels made from oriented strand board (OSB) with closed-cell polystyrene insulation. These are generally thinner than some of the other options discussed above while still providing a decent R-value in insulation.

Most companies produce these insulated subflooring products as tiles that are either rectangular (2x4 feet) or square (2x2 feet). They are usually installed as tongue and groove products to provide one simultaneous subflooring to reduce air leaks that would reduce the overall R-value. Furthermore, most insulated subflooring products do not need to be glued or screwed to the floor, allowing for quick installation.

Many top manufacturers offer advanced or improved versions of their insulated subfloors. These products will be slightly thicker due to the extra layer of oriented strand board (OSB) and polystyrene foam (XPS). If you have clearance space in your basement, these improved products are generally worth the slight increase in thickness as they can double the R-value of the floor.

For example, Barricade is one company offering insulated subfloor panels that are 1.25 inches thick and an R-value of 1.4. This product can be upgraded to a premium version that gets you a 3.2 R-value. Amdry is one of the most respected manufacturers of insulated subflooring panels, and their insulated panels achieve an impressive R-value of 7.0 for a slightly higher per-square-foot cost.

A quality insulated subfloor system provides the same benefits as a multi-layer approach described above. Though it might be more expensive, it does offer a thinner profile (important for low ceiling clearance heights in a basement) and a quicker, DIY approach to insulating your floor. The finish flooring can go directly on top of the insulated subflooring.

It will also help to reduce the risk of mold and mildew affecting your home's interior air quality. Mold spores are highly volatile, and even if you don't regularly use your basement, they can spread to every other area of your home.

If you are in the process of finishing your basement, insulating your concrete slab is an absolute necessity. Besides helping reduce heat loss and avoid excessive humidity issues, insulated subflooring can make your basement floor more comfortable underfoot. It will also generally improve your home's value. The only downside is that the insulated subflooring in basements with a low ceiling profile could push your head closer to the ceiling.

Heat loss through the concrete slab might not be as severe as heat loss through the roof or attic. However, for homeowners looking to maximize the energy efficiency of their homes, insulated subflooring will go a long way in improving the home's overall thermal performance.

As mentioned above, insulated subflooring doesn't need to be glued to the concrete slab. This means you won't have to worry about toxic chemical off-gassing from glue and adhesives. Unfortunately, most insulated subfloor products today are made from a wide array of chemicals such as OSB wood, foam, and the adhesives used to adhere the different layers of the board together. However, because the product is sold already manufactured, the chemicals should not off-gas too much into your home after installation.

Installing insulated subflooring is relatively straightforward, even if you don't have an abundance of do-it-yourselfer skills. The vast majority of the insulated subflooring options today come as "tongue and groove" tiles that are also very DIY-friendly. Though the panels are significantly more expensive than other possible ways of insulating a basement floor, you may save considerably on labor costs if you decide to self-install.

Amdry Insulated Subflooring: This product has the highest insulation R-values, between R5 and R7. These insulated subfloor panels can be used with almost every type of top flooring, including engineered or solid hardwood, laminate, carpet, vinyl, and tile. The subfloor also has small ventilation channels and deep drainage, which allow moisture and air to move freely below the floor's surface. This can help reduce even further unwanted odors, mildew, and mold. For homeowners looking to maximize the energy efficiency and thermal performance of their basements, Amdry will most likely be the best product for you.

Dricore Insulated Subflooring: Though Dricore insulated subflooring has slightly less insulation than Amdry, it is reportedly easier to install. The subfloor panels need no glue or tape due to the easy-to-install tongue and groove features. The R+ model will make your floor feel noticeably warmer with an R-value of 3.0, and it also softens finished floors against the hard concrete underneath. Dricore subflooring is also strong enough to support up to 3,153 lbs. per sq. ft. The Air Gap technology acts as a physical barrier to moisture, thus adding an extra layer of protection to your finished floor. With the Air Gap technology, both water vapor and moisture are controlled at the subfloor level. The Dricore Insul-Armor is also one of the best-insulated subflooring products on the market. It is specially engineered with 100 percent inorganic EPS foam that is lightweight and doesn't require power tools to cut it, making it even easier to install. It also achieves an impressive R-value of 4.1

Barricade Insulated Subflooring: Barricade is another company offering 2-foot by 2-foot by 1.25 inches high insulated subflooring panels. Each of the tiles has OSB wood on top and closed-cell polystyrene insulation below. Though the regular model only achieves an R-value of 1.4, the upgraded Barricade subfloor panel achieves an impressive 3.2 R-value. The panels fit side-to-side, much like tongue-and-groove flooring, for easy installation. Like the Dricore panels, they don't need to be glued down or attached to the concrete basement floor.

No matter what type of insulated subflooring you choose, these products will make your basement feel warmer and drier while also protecting your home's indoor air quality.

Article by:

Tobias Roberts

Tobias runs an agroecology farm and a natural building collective in the mountains of El Salvador. He specializes in earthen construction methods and uses permaculture design methods to integrate structures into the sustainability of the landscape.