Except for those that have concrete slabs, all houses have joists. While there are some instances where you could have less layers to your flooring, that would be the exception to the rule. In almost every instance there is the floor covering, the underlayment, the subfloor, and the floor joists.
The subfloor is the structure that lies between the floor joists of a home and the finished flooring (hardwood, LVP, etc). The subfloor creates a foundation and provides support for the finished flooring and identifying what type of subfloor you have is key before making your flooring purchase.
Floor covering is the topmost layer that you see and walk on such as ceramic tile, solid wood, laminate, engineered wood, luxury vinyl, or carpeting. Floor covering is not structural, so it will always have a subfloor under it.
Ceramic & Porcelain Tile
A major benefit of ceramic or porcelain tile floors in the basement is that you don't need an underlayment or subfloor beneath them. You can lay the tile directly over the concrete, as long as the slab is clean and level.
Above grade, hardwood, carpet, laminate and other floor coverings need a plywood or OSB panel subfloor, as they cannot be installed directly to floor joists. Below grade, a plywood or OSB subfloor is optional, depending on your choice of flooring.
Taking all these factors into account, subfloor material costs can range from as low as $2.50 per square foot for plywood to as high as $10 per square foot for Amdry or Barricade. Common subfloor materials include plywood, oriented strand board (OSB), Amdry, DRIcore, Barricade, Warmboard, and concrete.
R502.
Subflooring shall be a minimum of utility grade lumber, No. 4 common grade boards or wood structural panels as specified in Section R503. 2. Fireblocking shall be of any grade lumber.
Plywood is considered the most popular material used for subflooring, it has been used since the 1950s and remains one of the top choices for contractors. Standard plywood works perfectly fine as a subflooring material, but the best option is ¾” tongue-and-groove plywood subflooring.
Typically flooring is installed directly over the slab. Someone may laid a subfloor over the concrete but that would be unusual. You will only find out by taking up the existing floor.
If your planks already have a pad-attached underlayment, you most likely won't need an underlayment. However, if your flooring manufacturers installation instructions allow for an extra underlayment, adding an extra underlayment will provide improved sound reduction, insulation, and moisture protection.
There are many factors that can affect its longevity, such as the material, the amount of moisture it's exposed to, etc. However, most subfloors can last as long as the home itself. That said, you may have to replace your subflooring after 20 to 30 years if it has absorbed too much water too often.
You have the top layer that is your floor covering (Hardwood, Laminate, Vinyl, Carpet, etc.), next you have the underlayment (usually a thin layer of fiber, foam, rubber), below that you have your subfloor (plywood, OSB, concrete), and lastly you have the joists which are the foundation to your floors.
Replacing a subfloor may seem like a daunting task, but with the right tools, materials, and know-how, it's a project that can be tackled by DIY enthusiasts or professionals alike. By following this step-by-step guide, you can ensure that your floors remain strong, stable, and beautiful for years to come.
Given the complexity of subfloor repairs, you should really stick with a carpenter for this project. But if you want to install a new subfloor or underlayment over sound floor joists, hire a local flooring contractor for this step.
Without a proper subfloor, even the highest quality hardwood flooring can develop problems like squeaking, sagging, or warping over time. Think of it as the backbone of your flooring system – while it may not be visible, its role is absolutely vital for long-term performance.
Do walls sit on top of subfloor? Walls are built on top of a home's subfloor, so replacing the subfloor can sometimes require removing the walls.
Slab homes are more likely to experience severe foundation cracks than other foundation types. Damage may come from shifting soil, tree roots, freezing temperatures, or natural disasters. These cracks compromise the home's structural integrity and can lead to other issues, such as water infiltration and mold growth.
Remember, mobile homes and manufactured homes consist of layers, with the walls coming in after the subfloor; this means that a new subfloor will require specific tools. Inspect the subfloor part that is under your wall; if there is no damage there, do not disturb it.
While a subfloor is not necessary to add structural strength when you'll be laying finish flooring on top of a concrete slab (as in a basement remodel), subflooring over concrete offers two other advantages: Dampness control. Install a vapor barrier of plastic sheeting before laying the subfloor.
Both plywood and OSB are effective choices for your subfloor needs, but OSB may be a better option for a garage than plywood. Plywood is a better option for projects that require a lot of cutting and molding, while OSB is a good option for those who need to cover areas where moisture exposure may be an issue.
Plywood is the most popular material used for subflooring because it's strong and stiff. It comes in different thicknesses, with the thicker options being the best choice for a subfloor. The tongue-and-groove plywood is the best option because it has interlocking edges that help prevent movement.
The strength and solidity of floors are essential structural elements of all buildings. When flooring is installed, subfloor adhesive is applied below the panels to secure them at the panel-to-joist connection, which minimizes squeaks and prevents uneven flooring.
What Determines Subfloor Thickness. The minimum thickness of plywood for subflooring is about 5/8 inch. Since it does not hold fasteners as well as plywood, OSB must be a little thicker, or at least 23/32 inch.
Check the Level of the Subfloor
To check for small high or low spots that may not even be visible, place a long level or straight pipe on the subfloor. Move it around to different areas and mark any high or low spots you find with a pencil or marker. Most floors will have at least some slight variations.