1. What is Subfloor Screw Size?

The subfloor screw size calculator determines the appropriate screw length for securing subflooring. The general rule is to use a screw that penetrates completely through the subfloor and extends 1 inch into the joist below.

2. How Does the Calculator Work?

The calculator uses the simple formula:

Where:

• Subfloor Thickness — The thickness of your subfloor material (in inches)
• 1 inch — The recommended penetration into the joist below

Explanation: This ensures the screw properly secures the subfloor to the joist while preventing protrusion through the other side.

3. Importance of Proper Screw Length

Details: Using the correct screw length prevents squeaky floors, ensures structural integrity, and avoids damage to underlying surfaces. Too short screws won't secure properly, while too long screws may damage pipes or wiring below.

4. Using the Calculator

Tips: Measure your subfloor thickness accurately. Common subfloor thicknesses are 3/4" (0.75") for plywood or 1 1/8" (1.125") for OSB. Enter the value in inches.

5. Frequently Asked Questions (FAQ)

Q1: What if my subfloor is multiple layers?
A: Measure the combined thickness of all layers that will be secured together.

Q2: What type of screw should I use?
A: Use corrosion-resistant screws (like coated deck screws) designed for subfloor installation.

Q3: How far apart should screws be placed?
A: Typically 6-8 inches along edges and 10-12 inches in the field, following manufacturer recommendations.

Q4: Can I use nails instead of screws?
A: While possible, screws provide better holding power and reduce floor squeaks over time.

Q5: What about engineered floor joists?
A: Follow manufacturer specifications as they may require special fasteners or patterns.