How to Calculate Extra Material With Diagonal Decking

Step 1

Calculate the quantity of decking needed for a regular installation based on your existing plans. For example, a 10-by-10 foot deck requires 100 square feet of coverage. Since typical decking consists of 2-by-6 boards, you’ll need 200 linear feet, or 20 10-foot boards, to cover the planned deck’s surface.

Step 2

Add 15 percent for diagonal installations and add another 10 percent for miscuts or other possible errors. In this example, order 250 feet of boards.

Step 3

Calculate the quantity of extra joists needed. Diagonal installation requires joists spaced 12 inches on center, versus 16 inches for standard builds. For a 10-by-10 foot deck, a regular installation requires seven joists 16 inches apart between the two end joists; a diagonal installation requires nine joists 12 inches apart between the two end joists. Order exactly the amount needed.

Step 4

Double the center joist if the diagonal decking meets in the center of the deck in a herringbone pattern abutting a trim strip. Order an additional joist as well as a 2-by-4 trim strip and a 2-by-6 spacer between the doubled joists, recommends Scott Schuttner in "Building a Deck.”