For subflooring, the best type of plywood is typically 3/4 inch thick CDX plywood. CDX plywood is a construction-grade plywood where "C" and "D" refer to the grades of the front and back faces, and "X" indicates exterior-grade glue that provides some moisture resistance, making it suitable for subfloor applications where occasional moisture exposure may occur
. Key points about plywood for subfloor:
- Thickness: 3/4 inch thickness is standard and recommended to provide sufficient strength, rigidity, and prevent sagging between floor joists
- Grade: CDX plywood (C and D grades) is common and cost-effective for subfloors since appearance is not critical and it offers good durability
- Moisture resistance: While not fully waterproof, CDX plywood can handle some moisture, which is important for subflooring, especially in kitchens and bathrooms. For higher moisture areas, pressure-treated plywood or tongue-and-groove (T&G) plywood can be used for added moisture resistance and stability
- Tongue and groove (T &G): Using tongue and groove plywood is highly recommended because the interlocking edges reduce movement, gaps, and squeaks, improving the overall stability of the subfloor
- Alternatives: OSB (Oriented Strand Board) can be used but plywood generally offers better durability, moisture resistance, and ease of handling
In summary, 3/4 inch CDX plywood with tongue and groove edges is the best and most common choice for subflooring due to its strength, moisture resistance, and cost-effectiveness. For areas prone to moisture, consider pressure-treated plywood or marine-grade plywood for enhanced protection
