Choosing the right plywood size and thickness for your subfloor is essential for a durable, stable, and level foundation for your flooring. Whether you're building a new floor or replacing an old one, understanding plywood specifications helps prevent squeaks, warping, and structural problems.
How thick is subfloor? Learn how the right subfloor thickness can make your floors sturdier and more comfortable while lowering energy bills.
> Read more: 20 Types Of Plywood and Grades Used In Interior and Exterior (With Pictures)
What is Subfloor?
Before learning about plywood subfloor thickness, you need to understand about subfloor. Investing in flooring renovation can significantly boost your home’s value. To do it right, understanding the layers beneath the surface is essential. Flooring isn’t just the visible layer but comprises several important sublayers.
Underlayment
Directly beneath the top layer (carpet, vinyl, tile, hardwood) is the underlayment, typically 1/4 to 1/2 inch thick. This layer offers stability and comfort, often made from foam padding but sometimes wood or cement.
Subflooring
The subfloor, located under the underlayment, is critical for overall flooring stability. It attaches to the baseboard joists, forming the structural base. Common materials include plywood, particleboard, or OSB (oriented strand board) subfloor thickness, which consists of compressed wood flakes bound with adhesive, popular since the 1960s.
Subflooring not only provides structure but also acts as a barrier against moisture and air infiltration. It’s usually coated with resin to resist rot and corrosion. Without this protection, subflooring can warp from moisture, leading to squeaky or unstable floors.
> Read more: Top 9 Advantages of MDO Form Plywood
What Size Plywood Do I Use for a Subfloor?
Choosing the right plywood size and thickness for your subfloor is essential for a durable, stable, and level foundation for your flooring. Whether you're building a new floor or replacing an old one, understanding plywood specifications helps prevent squeaks, warping, and structural problems.
Common Plywood Sizes for Subflooring
The most commonly used plywood sheet size for subfloors is 4 feet by 8 feet (4’x8’). This size balances ease of handling and coverage, allowing efficient installation in most residential and commercial floor framing.
Recommended Thickness for Subfloor Plywood- 3/4 inch (19mm): The standard thickness for most subfloor installations over floor joists spaced 16 inches on center (OC). Provides strong support and minimizes deflection.
- 5/8 inch (15mm): Can be used for floor joists spaced closer together (12 inches OC), or for lighter loads.
- 1/2 inch (12mm): Generally not recommended for subfloors as it can flex and cause floor squeaks.
> Explore further: hdo vs mdo plywood, tongue and groove plywood
Factors Influencing Subfloor Thickness
What size plywood for subfloor? The minimum plywood thickness for subfloor is approximately 5/8 inch. Because OSB does not hold fasteners as effectively as plywood, it needs to be slightly thicker, with a minimum ply thickness for flooring of 23/32 inch.
Several factors influence optimal sub floor thickness, especially for insulation:
Joist Spacing
Flooring joist spacing affects subfloor plywood thickness. Closer joists (16 inches apart) can use thinner subfloors (1/2 inch), but wider spacing in older homes may require thicker materials (7/8 inch plywood or 1 inch OSB). Proper thickness of subfloor ensures floor stability and comfort.
Vertical Space
Subfloor thickness must consider R-value, the measure of insulation. OSB has a higher R-value (1.4 per inch) than plywood (1.1 per inch), offering better insulation. In limited vertical spaces, a higher R-value material is essential to maintain adequate insulation.
Underlayment
Underlayment can enhance insulation. High R-value underlayment allows for thinner subflooring, while comfort-focused underlayment might need thicker, more insulating subflooring. Balancing these factors ensures optimal flooring performance.
- Can be prone to warping
- Susceptible to insects
- Not as resistant to rot and decay as some other hardwoods
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Tips for Installing Subfloor Plywood
- Use tongue and groove plywood or edge-glued panels to reduce movement and squeaking.
- Leave a 1/8 inch expansion gap between sheets to allow for moisture expansion.
- Secure plywood with appropriate screws or nails every 6-8 inches along joists.
- Apply construction adhesive to joists before plywood installation for extra bonding and noise reduction.
> Read more: 1/8 inch plywood, 15/32 plywood, 19/32 plywood, 5x10 plywood
The above article has helped you determine what is the most suitable subfloor thickness for your house, also the plywood thickness for floor. VINAWOOD is proud to be able to provide you with the best flooring at the most suitable price. Please refer to the information on our official website.
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