Deck bracing is used to prevent uplift, shifting or racking of your deck that can cause your deck to fail over time. Though many building codes might not require bracing, it's a prudent practice in some types of deck construction. Decks perched high above ground tend to be more prone to unwanted movement and respond well to bracing. Deck posts that are installed on above-ground deck piers can also benefit from bracing to prevent them from pivoting where they are secured to the pier. Several techniques can be used to brace decks, but all must prevent racking and increase the strength and stiffness of your deck.
Y Bracing to the Sides of Posts
Installing bracing in a Y pattern is a popular technique for deck bracing. It offers strong support while providing a desirable appearance. To brace against the sides of the support posts, the ends of a 4-by-4 inch or 6-by-6 inch board is cut at a 45-degree angle to fit against one side of a post and the other end flush against the underside of the horizontal beam. If the posts are sandwiched between beams, one edge of each brace is inserted into the gap between the beams and secured in place with lag screws or bolts. The opposite end of each brace is secured flush against a side of a support post. Each set of braces secured to a post forms a Y.
Y Bracing to the Face of Posts
Lumber measuring 2-by-4 inches or 2-by-6 inches is used to brace a deck on the face of the support posts and horizontal beams, using the Y bracing technique. The ends of the bracing lumber are cut at a 45-degree angles. One end of each brace is secured to the face of the beam, aligning the cut edge flush with the top edge of the beam. The opposite end of each brace is secured to the face of the vertical support posts with the edges butted against each other and creating a Y.
For decks with long support posts and those on installed on slopes, X bracing adds sufficient support to prevent movement. This technique allows for longer supports, which are more suitable for tall posts. Lumber measuring 2-by-4 inches or 2-by-6 inches is commonly used where each board is secured from the top of one post and across to the bottom of the next post. A second board is secured in the same manner, starting at the top of the second post and crossing back over to the bottom of the first post, creating an X pattern. The X pattern is repeated between each set of posts around the entire deck.
Another technique used for tall decks is W bracing. The ends of 2-by-4 or 2-by-6 boards are cut at 45-degree angles and secured diagonally between posts where every set of four braces forms a W to the backs and fronts of the support posts. One cut end of a board is positioned at the top of the first post and aligned with its outside edge. The opposite end of the board is secured to a lower position on the next post. The next brace is secured in the same manner as the first but positioned on the opposite face of the second post and third posts. One end of the brace is secured at the same low position as the first brace and the other end is secured to the top of the third post. Additional braces are attached in the same alternating manner to add support to all posts creating W-shaped patterns.
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