Question 1

How far apart should deck joists be?

Accepted Answer

Standard joist spacing is 16 inches on center for 2x6 and 5/4x6 deck boards. For composite decking, check manufacturer specifications; many require 16-inch spacing or even 12 inches for diagonal installations. Using 12-inch spacing increases strength and reduces board bounce.

Question 2

What gap should I leave between deck boards?

Accepted Answer

For pressure-treated wood installed wet, use 1/8 inch or even butt boards tightly as the wood will shrink. For dry wood, leave 1/8 inch. For composite decking, leave 1/4 inch for thermal expansion. Always follow manufacturer guidelines.

Question 3

Should I use 5/4x6 or 2x6 deck boards?

Accepted Answer

5/4x6 boards are the standard deck board profile (1 inch thick). They are lighter, less expensive, and have eased edges for comfort. 2x6 boards (1.5 inches thick) are stronger and more rigid but heavier and costlier. Use 2x6 for heavy-use areas or wider joist spacing.

Question 4

How many screws per deck board?

Accepted Answer

Use 2 screws at every joist crossing, placed about 3/4 inch from each board edge. For a 12-foot board on 16-inch joist spacing, that is about 18 screws per board. Pre-drill near board ends to prevent splitting.

Deck Board Calculator

Frequently Asked Questions