How to Build Deck Headers

Install your ledger board on both sides of the window or chimney with lag bolts penetrating into the sill plate atop your house foundation wall. Follow the engineer’s or architect’s plans to install support posts on concrete piers and a beam across the posts. Run full-length joists out from the ledger board to a rim joist, which runs parallel to the side of the house. Fasten these joists with joist hangers and galvanized nails to the ledger board and rim joist.

Install double joists closest to the bay window or chimney to support the header. While typical deck joists are 2-by-8s, your architect may specify 2-by-10s or larger so that these double joists can do their job to safely support the header and its joists, which connect the header to the rim joist.

Install a single header directly in front of your window or chimney if the span is four feet or less. Cut dimensional lumber -- 2-by-8s or larger -- per your design plans to fit the span. Double the header if the span is four to 10 feet, face-nailing one header to another with 2 ½-inch nails. Avoid a design that calls for a header greater than 10 feet. Hang the header from single or double joist hangers, as appropriate, fastened by galvanized nails between the double joists.

Install the remaining joists, called tail joists, between the header and the rim joist. Cut the joists to fit and nail in place from joist hangers.