How to Build Porch Stairs

Posted by in Home Improvement Tips, on September 24, 2016

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Ask This Old House general contractor Tom Silva builds a safe and solid set of porch stairs. (See below for a shopping list, tools, and steps.)

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Shopping List for How to Build Porch Stairs:
– Pressure-treated 2x6s and 2x12s, for building the new stairs
– 3-inch deck screws, to fasten together the stair parts
– 8-inch structural timber screws, for securing the staircase to the house
– 3-inch masonry screws, to fasten bottom frame to concrete walk
– PVC trim board and plugs, for making the risers and trimming out the stringers
– Composite deck boards, used as stair treads
– Welded-steel handrail
– Composite railing system

Tools for How to Build Porch Stairs:
– Wrecking bar, to pry up the old stair treads
– Reciprocating saw, for cutting out the old staircase
– Framing square, to lay out stair stringers
– Circular saw, to cut lumber
– Jigsaw, for notching stringers
– Impact driver, for driving screws
– Hammer-drill, to drill into concrete
– Miter saw, for crosscutting lumber to length
– Socket and ratchet wrench, to tighten hex-head fasteners

Steps for How to Build Porch Stairs:
1. Pry off the treads from the upper step to gain access to the tops of the stringers.
2. Use a reciprocating saw to cut through the top end of the stringers, freeing the staircase from the porch.
3. Remove and discard the old staircase and any leftover debris.
4. Use a circular saw and jigsaw to cut six new stair stringers from a pressure-treated 2×12. Cut four steps into each stringer.
5. Screw a pressure-treated 2×6 to the existing porch frame to provide extra support for mounting the staircase.
6. Space the six stringers 16 inches on center, then fasten a 2×6 across the tops of the stringers. Attach the 2×6 with 3-inch decking screws.
7. Screw a 2×6 across the bottom ends of the stringers, then attach a 2×6 toekick to the previously installed 2×6.
8. Set the stringer assembly against the porch and secure it with several 8-inch structural screws.
9. Use a hammer-drill to bore screw-pilot holes through the bottom 2×6 and into the concrete walk.
10. Fasten the bottom of the staircase to the walkway with 3-inch masonry screws.
11. Cut four risers from PVC trim boards.
12. Attach each PVC riser to the stringers using specially designed screws. Conceal each counterbored screwhead with a PVC plug.
13. Cut and attach PVC trim boards to outer surfaces of the stringers on the left and right end of the staircase.
14. Cut stair treads from composite decking; screw the treads to the stringers.
15. Install a welded-steel handrail, making sure it’s between 34 and 38 inches above the nose of the stair tread.
16. Assemble a composite railing system, which includes a handrail and balusters, to fit alongside the welded-steel handrail.

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