How to Estimate Drywall Screws

Drywall screws should be no more than 7 inches apart to pass the strictest requirements; in the case of drywall screws, more is better.

1. Determine if there are metal or wood studs under the drywall. Metal studs require a chisel point or fine thread drywall screw; wood requires coarse thread.

2. Select the screw length. For 1/4-inch drywall, the screw length must be at least 1 inch long. Drywall that is 3/8-,1/2-, 5/8-inch requires 1 5/8-inch screws. Double layers of drywall demand a 2 1/2- or 3-inch drywall screw.

3. Calculate the square footage of installed drywall. You can also figure the number of drywall sheets, factoring in the framework spacing. The closer the framework, the more drywall screws you will need. The average spacing for framework is 16 inches on center.

4. Estimate that an average 4-by-8 sheet of drywall will have seven screws along each support, including the edge. A sheet of drywall hung horizontally will have seven supports based on 16 inches on center. Multiply seven supports by seven screws per support, which totals 49 drywall screws per sheet.

5. The alternate estimate is one-and-one-half screws per square feet of drywall surface area. For example, sixty 4-by-8 foot sheets of drywall times 32 square feet each equals 1,920 square feet of surface space; 1,920 square feet times one-and-one-half screws per square foot equals 2,880 drywall screws.

6. Add 10 percent for extra drywall screws to allow for oddly shaped edges of drywall and for dropped or broken screws.

Tip

Florida, a hurricane zone, requires, per Florida Building Construction code (section 2508.5.4 Fasteners): "Fasteners shall be spaced not more than 7 inches on center at all supports including perimeter blocking." Florida building code is one of the strictest in the nation; by following this code requirement other jurisdictions will not have issue with code violations.