How to Determine How Much Lumber for a Deck

Obtain deck building plans to help you with the construction of your new deck. Plot out the area where your deck is going to go in reference to your home and mark it out with stakes.

Measure the area where you are planning to put your deck with a measuring tape. Make sure to get a precise length and width measurement in feet and inches.

Go to your local home improvement or building material supply store and select the width of the lumber you want to use. Most standard decking boards are between 4 to 6 inches wide, with 6 inches considered to be ideal. Boards that are 8 inches wide or larger are more likely to crack and split over time and should be avoided.

Select the length of the boards you want to use. Buy boards that will run the full length of the deck whenever possible. Most lumber yards sell boards that are 16 feet long or longer, though the cost may be more per board.

Select the thickness of board you want to use. Most decking is between 1 to 2 inches thick. Radius-edge boards that are 5/4 material typically measure between 1 to 1-1/4 inches thick and are commonly used for decking. If your joists are going to be more than 16 inches apart, you will need to select thicker boards. Avoid boards that are less than an inch thick, as these may not be sturdy enough.

Calculate how much lumber you will need for your deck by determining how many pieces of lumber you will need to build your deck. You can calculate decking by dividing the size of your boards into the total square footage of your decking (length x width), or by using a deck flooring calculator such as the one provided by Decks.com (see Resources).