How to Frame a Large Deck

Outline the deck space with stakes and twine, working from a house wall with a door. Measure from corner to corner with a tape measure and adjust stakes until the diagonal distances are identical, meaning the deck is square. Mark places for two lines of piers, one 8 feet from the wall, the second 15 feet, with three piers in each line, two on the sides 1 foot inside the deck edge and one in the center.

Remove bottom layers of siding on the house to expose the rim joist on the house wall, typically a 2-by-8-inch beam. Install a 16-foot 2-by-8 ledger board, fastened to the rim joist with lag bolts that have a screw point and a bolt header. Drill pilot holes through the ledger, level it with a level, then drive the bolts in with a wrench. Space lag bolts about 2 feet apart and stagger them so all are not driven at the same height in the boards.

Measure the height of the ledger from the ground and place piers to support 6-by-6-inch vertical posts with a 6-by-6 beam on top. Dig out dirt or pour footings under the piers so the tops of the beams on them will be 2 inches below the height of the ledger, to create a slope away from the house. Secure the precast piers and use a level to get them plumb. Use piers with built-in brackets to support vertical posts.

Cut six 6-by-6-inch posts to the proper height and fasten them in the pier brackets with galvanized screws, driven with a screw gun. Use a level to plumb them. Lay two 16-foot-long 6-by-6-inch beams on top of the posts. Fasten them with 16d framing nails toenailed diagonally with a hammer, or use metal joist brackets to secure the beams, parallel to the ledger board.

Install eight 2-by-8-inch joists between the ledger and the outer beam, across the center beam. Fasten joists to the ledger with metal joist hangers, secured to the ledger and the joist with 8d galvanized nails. Toenail the joist to the center and outer beams with framing nails. Set the two outside joists 4 inches in from the end of the ledger; space others 24 inches apart between them.

Nail metal flashing on top of the ledger, one side over the 2-inch top, the other up the house wall. Fasten flashing with shingle nails to the house sheathing; do not put any nails into the horizontal plane. Replace siding down to the flashing. Set 4-by-4-inch railing posts at the four corners and over the center beam. Fasten these with framing nails driven through the joists and toenailed from the outside edges.

Cover the deck with 1-inch flooring, either tongue-and-groove or butt-jointed with sides set closely together. Nail flooring to joists with galvanized nails. Cut flooring boards with a circular saw where necessary to accommodate the railing posts. Put a 2-by-8-inch rim joist around the outsides of the deck. Finish the deck by making a railing of 2-by-4-inch spindles and rails.