How to Install Deck Stair Stringers and Treads

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How to install the 2×12 solid and sawn stringers, stair treads, hanger board and guard rail for the upper flight of deck stairs.

Table of Contents

  1. Planning and Building Wood Deck Stairs with Landing
  2. Tear Down Old Wood Deck Stairs and Landing
  3. Remove Wood Deck Stair Landing Support Posts and Concrete Footers
  4. Build Deck Stair Landing: Pour Concrete Footers and Install 6×6 Posts
  5. Deck Stair Landing: Saw Post-to-Beam Support Notches
  6. Deck Stair Landing Beam and Joist Framing
  7. Deck Stair Stringer Hanger Board and Simpson Strong-Tie LSCZ Stringer Connectors
  8. Install Wood Deck Stair Stringers and 4×4 Newel Posts
  9. How to Frame a Wood Deck Stair Landing
  10. Build Wood Deck Stairs – Layout Solid and Sawn Stringers
  11. How to Install Deck Stair Stringers and Treads (you are here)
  12. Build Wood Deck Stairs and Landing – Completed Job Photos

How to Install Deck Stair Stringers and Treads

The upper stairs 2×12 outer solid and middle sawn stringers are mounted using Simpson Strong-Tie LSCZ stringer connectors the same way as the lower stairs:

Wood Deck Stair Upper Flight and Landing Framing

Wood Deck Stair Upper Flight and Landing Framing

Simpson Strong-Tie TA9Z-R ZMax staircase angles are fastened to the outer solid stringers at the locations marked for the stair treads, then pre-stained 2×12 WeatherShield stair treads installed. The stair treads are fastened to the staircase angles with SD 1/4 x 1-1/2 inch screws. Then two #8 x 3 inch wood screws are driven in from the top of the tread to fasten it to the sawn middle stringer.

Blocking between the 4×4 guard posts and stringers conforms to Figure 36 “Stair Guard Requirements” on Sheet 19 of the Deck Code:

Wood Deck Stair Framing - 4x4 Guard Post Blocking between Stringers

Wood Deck Stair Framing – 4×4 Guard Post Blocking between Stringers

Deck Stair Guard Rail

The original stairs did not have an inside guard rail. The home builder used long 2×2 pickets to prevent falls instead. The new stairs are built narrower with 36″ wide treads (“clear space”) to make room for a proper rail. Compare the photos above and below:

Old Wood Deck and Stairs Built in 2000

Old Wood Deck and Stairs Built in 2000

The 4×4 guard post at the top of the stairs is mounted to the 2×12 stringer because there wasn’t space to fasten it to the deck joists:

Wood Deck Stairs and Landing Guard Rail Framing

Wood Deck Stairs and Landing Guard Rail Framing

I didn’t like having to mount the top guard post to the stringer because this method is not as strong:

Wood Deck Stairs - Guard Rail Framing

Wood Deck Stairs – Guard Rail Framing

My solution was to drill pilot holes and drive two Simpson Strong-Tie Deck-Drive #12 x 4 inch stainless steel wood screws horizontally to tie the 2×6 rail caps together. Lateral (“push”) loads are transferred from the stair rail to the deck rail making it very rigid. The screw recesses were filled with exterior caulk to keep out rain water:

Wood Deck Stairs - 2x6 Cap Rails Screwed Together

Wood Deck Stairs – 2×6 Cap Rails Screwed Together

Deck Stair Stringer Hanger Board

The interior and middle stringers are mounted to the stair hanger board with the outside stringer mounted to the deck rim joist and 6×6 post. The stringer placement was constrained by the original stair configuration and Code requirement for 36″ wide stairs:

Wood Deck Stairs - Stringer Hanger Board Framing

Wood Deck Stairs – Stringer Hanger Board Framing

The stringer connections are shown in the following photo. BTW – the hanger board appears to be uneven but it’s level. The problem is the deck joists are not square the deck!

Wood Deck Stair Stringer Installation - Hanger Board and LSCZ Connectors

Wood Deck Stair Stringer Installation – Hanger Board and LSCZ Connectors

View of the stairs and landing platform progress:

Wood Deck Stair and Landing Guard Rail Framing

Wood Deck Stair and Landing Guard Rail Framing

Deck Stair Landing Guard Rail and Newel Posts

4×4 newel posts are bolted to the stringers with 1/2 inch galvanized bolts, washers and nuts. The newel posts simply sit on the 5/4 deck boards. The newel posts are initially sawn longer than needed. The slope will sawn to match the 2×4 top rail after temporarily screwing the top rail in place, mark the slope and saw the top with a circular saw.

The landing guard has a 2×6 top rail with 2×4 side rails. 2×2 pickets will be installed later.

The outer solid stair stringers are screwed to 4×4 guard posts (far right side of the photo behind the newel posts) installed the exact width of the stairs to prevent side-to-side movement:

Wood Deck Stair to Landing Framing

Wood Deck Stair to Landing Framing

Deck Stair Stringer 2×4 Base Plate

The stringers are notched to fit a 2×4 base plate screwed to the landing 2×8 joists and interior blocking. The stringers rest on the base plate without nails or screws. The plate prevents forward movement of the stairs:

Wood Deck Stair Landing Attachment Detail

Wood Deck Stair Landing Attachment Detail

View under the stairs showing how the 2×12 stringers rest on the deck landing with 2×6 blocking between the stringers. The stringers are not nailed or screwed to the landing. The 2×4 base plate is out of view on the far side of the blocking:

Wood Stair Stringer to Landing Installation Detail

Wood Stair Stringer to Landing Installation Detail

The aluminum handrail and 2×2 pickets are installed in Build Wood Deck Stairs and Landing – Completed Job Photos.

Thanks,

Bob Jackson

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