How to Brace Tall Decks

Bracing can be added during or after deck construction.

Backyard decks are supported by a framework of wooden posts and joists, which are anchored in concrete footers. High-standing decks may require extra bracing, however, to prevent shifting and collapse. High structures are less rigid since their center of gravity is raised and the structural elements that support them are unable to carry the load over long distances. Bracing can be installed in several forms, including Y, X and W shapes.

Things You'll Need

• Miter box
• Saw
• 2-by-4 inch lumber
• Tape measure
• Power drill
• Screw gun
• 3 1/2-inch decking screws
• 1/2-inch lag bolts, washers and nuts
• Work gloves
• Eye goggles

Instructions

1. Use a miter box and saw to cut one end of a 2-by-4 inch stud at a 45-degree angle. Measure 24 inches from the shortest edge of the mitered end and mark it with a pencil. Use the miter box and saw to cut a 45-degree angle outward from the pencil mark so that the stud piece now has an opposing outward 45-degree angle at each end. Use this template to mark and cut all of the braces to follow. If you are installing braces on the side of the post and joist, skip to Step 3.

2. Place the mitered brace into the corner formed by the deck's vertical support post and the rim joist that runs around the outside edge of the structure. Drill two pilot holes through the brace and into the rim joist or post at both ends. Use a screw gun to fasten the brace into position with 3 1/2-inch decking screws.

3. Lay the brace over the deck's rim joist and vertical support post so that the mitered ends sit flush with the outer edges of both elements. Make pilot holes through the brace and into the wood beneath it. Use the screw gun to drive 3 1/2-inch decking screws into each pilot hole.

Tips & Warnings

• If your deck has support beams on both sides of the vertical support post, the best option may be to place a brace between them. Cut both ends of the brace at 45-degree angles then place it in position between the two beams and against the side of the post. Drill pilot holes completely through all three elements at both ends then install 1/2-inch lag bolts, washers and nuts to hold it all together.

• Cross bracing, where two braces form an "X" between each set of upright posts, or "W" bracing, where braces alternate in an up and down pattern between each post, are systems that provide even more strength to decks, which require the maximum possible support, such as those on sloped ground or very high off the ground.

• High decks can be fitted with steel columns rather than wooden posts. Steel is a far stronger material, which will resist bending and cracking.

• Use caution when working with dangerous tools, such as saws, hammers and nails. Wear work gloves and eye protection for safety.

• The braces you cut must all be identical in size. Discrepancies can cause one side to buckle the other.

References

• Decks: Deck Bracing
• Deck Magazine: Elevated Decks
• City of Lancaster Building Department: Deck Construction Specifications.
• National Association of Realtors: Adding Blocking and Bracing
• Creative Homeowner: Adding Blocking and Bracing to Your New Deck

Resources

• ThisOldHouse: Building a Safe Deck
• AskTheBuilder: Building a Deck