How to Build Stairs for a Deck on a Sloped Site
Building a deck takes time, and their are specific steps you need to follow to get the job done right. When building on a sloped site, take extra care to ensure each step is complete after moving on to the next. In this case, once you've determined rise and run and installed a landing pad, you're ready to start building the stairs.
Stairs have to withstand plenty of use, so choose lumber that is straight and free of knots and other defects. Pay extra for Select or No. 1 lumber. Some lumber dealers sell 2x12s specifically approved for use as treads or stringers.
If you accidentally break a step off a stringer, drill pilot holes, apply exterior grade polyurethane glue, and drive screws or nails to reattach it.
The full width of the stringers must be firmly attached to the deck framing. Usually the outside or header joist is not deep enough, so you need to install a 2x6 or 2x8 brace directly below. This may require some improvising. Build out from the beam or from the posts so that the brace is as strong as the joist above it.
Once the landing is finished and the layout calculated, expect to spend four to five hours to cut and install stringers, a toe-kick, treads, risers, and rail posts for an eight-step stairway. Make sure you're comfortable cutting lumber at angles, and fastening pieces with nails or screws.
What You Need
- Tape measure
- Circular saw
- Framing square
- Layout square
- 2x12 for stringers
- 2x lumber or decking for treads
- 2x4 toe-kick
- 4x4 posts
- Post anchors
- Angle brackets
- Screws or nails
- Masonry screws
Step 1: Cut Lines
Test the partially cut stringer to make sure it fits between the deck and the landing with the tread lines level. With a circular saw, cut each line. Don't cut farther than the intersection of the tread and riser lines.
Step 2: Finish Cuts
Finish the cuts with a handsaw or a saber saw. Take care not to bump the resulting teeth of the stringer. Use the first stringer as a template for laying out the others.
Step 3: Anchor and Square Stringers
Attach a crossbrace directly below the rim or header joist and anchor the stringers to the brace. The tops of the notched stringers (and the metal cleats on closed stringers) must line up so a tread can rest across all of them. Square the stringers to the deck with a framing square, and anchor them with angle brackets.
Step 4: Attach Toe-Kick
Slip a 2x4 toe-kick under the inside stringers and against the insides of the outside stringers. Drill holes through the toe-kick; then drill holes into the landing using a masonry bit. Fasten the toe-kick to the landing with bolts and anchors or masonry screws. Drill angled pilot holes and drive screws or nails to attach the stringers to the toe-kick.
Step 5: Fasten Post Anchor
Attach a post anchor to the landing where the post is at the full width of the stringer. Use the epoxy-and-threaded-rod method. Fasten the post to the anchor. Plumb the post and drill a hole for a carriage bolt through the post and stringer.
Editor's Tip: Be sure the carriage bolt will not interfere with the tread or tread hardware. Tap the bolt through and fasten it with a washer and nut.
Step 6: Cut Treads
If the outside stringers are notched, cut the treads so they overhang 1-1/2 inches on each side. If you are using closed stringers, cut treads to fit between them. Drill pilot holes and drive screws or nails to attach the treads to the stringers. Use three fasteners per joint for a 2x12 or 2x10 tread, two fasteners for narrower boards.
How to Make a Closed Stringer
To make a closed stringer, make only one cut at the bottom and one at the top. Draw lines indicating both the bottoms and tops of the treads. Drill pilot holes and attach the tread cleats with 1-1/4-inch lag screws.
How to Notch for a Toe-Kick
The bottom of an inside stringer rests partly on the slab and partly on the 2x4 toe-kick. Use a circular saw and handsaw to cut a notch 1-1/2 inches high and 3-1/2 inches deep.