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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.
Table of Contents
What is an Insulated Subflooring?
Insulated subflooring is an excellent way for homeowners to keep their basement flooring dry and warm while reducing draftiness. Typically, insulated subflooring consists of a sheet of closed-cell polystyrene insulation between two sheets of oriented strand board (OSB).
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.
How Thick is Insulated Subfloor?
Most insulated subflooring products will be between 1 and 2 inches thick, with the average at around 1.25 inches. The thickness of the subflooring product will depend on the insulation in the product.
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.
How is Insulated Subflooring Made?
Insulated subflooring is generally made by piecing together OSB wood on the top layer with foam-based insulation underneath. Most brands use closed-cell polystyrene insulation because it offers waterproofing and insulation capacity.
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.
Do Basement Floors Need to be Insulated?
Insulating your basement floor is generally a good idea, even if your basement will remain unfinished for some time. Putting in a layer of insulated subflooring on top of your concrete slab will drastically reduce unwanted heat loss from your home.
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.
What are the Best Brands of Insulated Subflooring?
For homeowners who believe that insulated subflooring might be the best option for their basements, most builders generally rely on three different companies providing insulated subflooring products: Amdry, Dricore, and Barricade.
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.
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.
