How to Attach Stairs to a Deck

Hold the stringers up to the deck to determine where they will hit. You can either cut your own stringers or purchase them precut. The stringers should hit the end joist of the deck -- the vertical boards that create the frame of the deck and support the deck floorboards. If the joist isn't long enough to attach the stringers, attach a two-by-four directly below the joist. Predrill holes through the two-by-four and into the deck posts that hold the deck up. Screw the board into place using deck screws.

Mark the locations of the stringers on the deck joist based on the length of the stair treads. Include a mark to indicate where the top of the stringers will hit and where each stringer is located horizontally on the deck. Consult the local building code to determine how far apart the stringers should be, a distance that usually ranges from 16 inches to 24 inches. Divide the total width of the treads by the distance allowed between stringers to determine how many you need.

Align the stringers properly using a framing square to ensure they are straight. Drill pilot holes from the back side of the joist into the stringers. Use three holes for each stringer.

Attach each stringer to the deck with 3-inch deck screws through the pilot holes you drilled. Ensure the stringers are level both before and after you screw them in place.

Install an angle bracket on the inside of each stringer for additional support. Installing the bracket on the inside allows you to cover it up with the treads.

Secure the stringers at the bottom to the concrete landing with angle brackets and masonry screws. Lay a level across the stringers to ensure they are level.

Lay the tread boards across the stringers so that 1 inch hangs off on either side. Predrill holes along the tread boards so you can easily attach the treads to the stringers with screws.

Predrill holes and screw on toe kick boards that cover the rise of each step if desired.