Deck Framing Basics

Framing the Deck Perimeter

Learn how to add stability to your deck by correctly framing its perimeter.

The planning is done, your foundation is laid out, and the piers are poured — you’re no doubt chomping at the bit to start sawing some wood. Building a deck frame is satisfying work and tolerant of minor errors — perfect for the determined DIYer.

The single most-important framing member is the ledger board. Once installed, it acts as a guide for a deck frame that’s level and square. It’s a good idea to mark joist locations on the ledger and on the front-facing rim joist before installation, when you can lay the framing members side-by-side on a pair of sawhorses.

The ledger is attached directly to the structural framing of your house — a rim joist is one of the more common points for this connection. Siding must be cut away to expose the rim joist; never install a ledger over any kind of siding. Secure the ledger with lag bolts, not screws or nails. Improper installation of the ledger is the leading cause of deck failures in the U.S. — be sure to check with your local building authorities for code requirements in your area.

With the ledger and footings in place, install the support posts. Most building codes allow pressure-treated posts rated for ground contact to be installed into foundation holes that are then filled with concrete. Although this method satisfies codes, over time the post is still likely to rot and weaken. Many professional deck builders prefer to secure posts to concrete piers with galvanized metal connectors that hold the end of the post above the concrete base and the ground to prevent rot.

Plan to install support beams directly onto the tops of posts — not bolted to the sides of the posts — using metal post-to-beam connectors. Remember that the joists will rest on top of the beam so you’ll need to calculate carefully—the top of the beam should be level with the bottom of the ledger. Use a water level or a transit to mark the height of each support post, and cut it to length.

Decks that are more than 30 inches from grade benefit from having cross- or X-bracing installed between posts. Diagonal X-bracing stiffens supports and helps prevent lateral movement and uplift caused by high winds or earthquakes.

Install joists using galvanized metal joist hangers and approved fasteners. Building inspectors often cite improper fasteners, such as deck screws and ungalvanized nails, as a leading deck code violation.

Once the joists are in place and the rim joists are attached, don’t secure the joists to the beams just yet. Check for square by measuring diagonals, and tweak as needed. Once you’re satisfied the deck joist frame is square, secure the joists to beams with toenails or galvanized connectors.

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