Deck Stair Installation

Measure for the stair stringers and posts using a tape measure, and transfer these measurements to a stairway elevation drawing. Use a pencil and framing square and outline on the drawing where the stair stringers will attach to the side of the deck. Typically, a common deck stairway is made from 2-by-12 stringers, and a series of treads attached with metal cleats. The posts sit back 18 inches from the end of the stairway to help anchor the stringers and railings. Commonly, decks posts are 36 to 42 inches tall.

Locate where the post footings are. Typically, they will be 18 inches inside the outer point of the stairway span. Place a 2-by-4 board on the deck verifying it is level and square to the side of the deck using a carpenter's level.

Mark the ground at the center points of the footings using a plumb bob.

Dig holes and pour the footings for the posts. Dig the holes using a power auger to a depth allowed according to your local building code. Pour gravel in the bottom of each footing. Mix concrete according to the manufacturer's direction and pour it into each hole.

Allow the concrete to set until it holds its shape, then attach metal post anchors to the footings according to the manufacturer's directions. Insert 4-by-4 posts.

Lay out the stair stringers, using tape to mark the rise measurements on one leg of the framing square, and transfer this measurement to the other leg. These instructions are based on a run of 11 1/4 inches deep.

Position the framing square at one end of the stringer flush against the tape marks on the edge of the board. Outline the rise and run for each step using a pencil. Draw in the tread outline against the bottom of each run line with the pencil. Trim the ends of the stringers using a circular saw.

Attach metal tread cleats flush with the bottom of each tread outline using lag screws and a ratchet wrench. Drill 1/8-inch pilot holes, to prevent the screws from splitting the wood, before drilling in the screws.

Attach angle brackets to the upper end of the stair stringers with joist hanger nails and a hammer. Flush the brackets with the cut ends of the stringers.

Position the stair stringers over the stringer outlines against the side of the deck.

Attach the stringers by nailing the angle brackets to the deck using joist hanger nails and a hammer.

Drill two pilot holes through each stringer and into the adjoining post. Drill into the posts to a depth of 1/2 inch with a 1-inch spade bit and a drill.

Attach the stringers to the stair posts with lag screws, washers and a ratchet wrench. Seal all screw heads with silicone caulking and a caulking gun.

Measure the width of the stair treads using a tape measure. Cut two 2-by-6 boards for each tread with a circular saw.

Position the front 2-by-6 board on the tread cleat so the front edge is flush with the tread outline on the stringers. Repeat for each step.

Drill pilot holes using a drill and drill bit. Attach the front 2-by-6 boards to the cleats with lag screws and a ratchet wrench.

Place the rear 2-by-6 boards on the cleats leaving a small space between the boards using a framing nail as a spacing guide. Drill pilot holes and attach the 2-by-6 boards to the cleats using lag screws and a ratchet wrench.