Build Wood Deck Stair Landing: Concrete Footers and 6×6 Posts

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How to pour concrete footers and mount 6×6 deck posts to build a deck stair landing. The basic steps are:

  1. Carefully layout the post footers such they’re square and precisely positioned.
    Any mistakes here will cause the stair landing to be out of position and costly to correct.
  2. Dig the post footers.
  3. Make a wood frame for pouring and finishing concrete.
  4. Set the anchor bolts in the wet concrete for the metal standoff-post base.

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¬† (you are here)
  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 Connector
  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
  12. Build Wood Deck Stairs and Landing – Completed Job Photos

Build Wood Deck Stair Landing: Concrete Footers and 6×6 Posts

The deck stair landing is built to the “free standing deck” Building Code requirements on Sheet 14. I carefully measured where the center of the post footers should be positioned, then dug 17 inch deep by 22 inch square footers. The Building Code in my area requires 12 inch deep footers and I wanted to exceed the minimum. Your local Code may require much deeper footers to be below the frost line.

The 6×6 deck post footer construction steps are:

  1. Build box frames with 2×4’s.
  2. Remeasure the centers by referencing the main deck.
  3. Drive in 1/2 inch lengths of rebar which were plumbed (made vertical) with a level.
  4. Check the distance between the rebars are the same with a tape measure.
  5. Dig a rough channel, then pound 2×4 frames firmly into the ground, making sure they’re level.
    The frames must not move. Drive in wood stakes and screw it to frame if needed.
  6. Looped carpenter’s string around the rebars.
  7. Verify the string makes 90 degree corners with carpenters angle.
  8. Mark the center of rebar (and hence the footer) with a red felt tip pen on the 2×4 frames.
    This is so I’ll know where to set the concrete anchor bolts after the rebar is removed.
Build Deck Stair Landing - Layout Concrete Post Footers

Build Deck Stair Landing – Layout Concrete Post Footers

Closeup of the footer, rebar and red center marks on the 2×4 concrete frame:

Build Wood Deck Stair Landing - 16 inch Deep Concrete Footer and Frame

Build Wood Deck Stair Landing – 16 inch Deep Concrete Footer and Frame

Before pouring concrete, the footer ground bearing conditions must be checked by the Building Inspector.

Pour Deck Post Concrete Footings

I rented an electric concrete mixer, mixed 80 lb bags of Quikrete Concrete Mix No. 1101 and poured the post footings. A concrete calculator is very helpful to figure out how many bags are needed. Buy an extra bag or two so you don’t run short during the pour.

Have the 1/2 in diameter by 10 inch long galvanized concrete anchor bolts ready, then pour the footers. Consolidate the concrete by working a 2×4 board up and down to remove bubbles and fill all crevices as show in this project. Trowel the concrete even with the wood frame, then insert the anchor bolt using the red center marks on the frame as a reference for the center. Don’t push the anchor bolt straight down, rather cut it in at an angle and finish with the trowel. The anchor bolt must extend between 3/4 to not more than 1 inch high above the concrete for a Simpson Strong-Tie ABA66Z post base. The post base provides a 1 inch standoff.

The new post footer and anchor bolt:

Build Wood Deck Stair Landing - Concrete Post Footer and Anchor Bolt

Build Wood Deck Stair Landing – Concrete Post Footer and Anchor Bolt

Place a plastic sheet over the concrete to limit evaporation and let it cure for a few days per the manufacturer’s instructions.

Mount the Simpson Strong-Tie ABA66Z 6×6 Adjustable Post Base

The ABA66Z provides a 1 inch standoff to raise the deck post off the concrete to help prevent wood rot. I chose the ABA66Z instead of the PBS66HDG because:

  • The ABA66Z features an oval slot to fine tune the post alignment and/or make corrections for a twisted post.
  • The stair landing is a less demanding application using much shorter ~7 feet tall posts versus over 15 feet on the main deck.

Place the ABA66Z over the 1/2 inch concrete anchor bolt and fasten it with the galvanized washer and hex nut. The anchor bolt has the same threads as standard deck bolts:

Build 6x6 Deck Wood Stair Landing - Simpson Strong-Tie ABA66Z 6x6 Post Base Anchor Bolt Nut and Washer

Build 6×6 Deck Wood Stair Landing – Simpson Strong-Tie ABA66Z 6×6 Post Base Anchor Bolt Nut and Washer

For now, only make the nut finger tight. Once the posts are sawn evenly, mounted and aligned the nut will be tightened with an open-ended wrench through the left or right side of the base.

Simpson Strong-Tie ABA66Z Post Base Fastened to Concrete Footer

Simpson Strong-Tie ABA66Z Post Base Fastened to Concrete Footer

Mark Wood Deck Posts for Sawing at the Same Height

Place the 6×6 post on the standoff base and drive in two Simpson-Strong Tie #10 x 1-1/2 inch SD screws on each side (four total screws) because this is a temporary mounting:

6x6 Deck Post - Temporarily Mounted on Simpson Strong-Tie ABA66Z Post Base

6×6 Deck Post – Temporarily Mounted on Simpson Strong-Tie ABA66Z Post Base

The four 10 feet tall 6×6 posts temporarily set in place to measure & mark where to saw off the posts for the deck stair landing:

Build Wood Deck Stair Landing - Temporarily Set 6x6 Posts in Place to Measure and Mark for Sawing

Build Wood Deck Stair Landing – Temporarily Set 6×6 Posts in Place to Measure and Mark for Sawing

To mark the height were each post will be cut to evenly support the stair landing:

  1. Label each post with a number 1, 2, 3 and 4 and it’s location so you’ll know which post goes where after sawing.
  2. I fastened a very straight 2×4 between the two 6×6 main deck posts at the height where the posts should be sawn off evenly for the deck stair landing.
  3. A 10 feet long aluminum straight edge is set across the 2×4 board and against the post.
    • The posts will wobble and lean a bit on the Simpson standoff post base, so my helper held each steady and plumb referencing a spirit level until I could mark it. (Two spirit levels are required, one for me and another for my helper.)
  4. The 10 ft straight edge is leveled by setting 4 feet long level on it, then I marked a level line where to cut on the post face:
Build Wood Deck Stair Landing - Mark Level Lines on 6x6 Support Posts

Build Wood Deck Stair Landing – Mark Level Lines on 6×6 Support Posts

After marking the height where to cut each post – each is different due to the uneven ground – I unscrewed the posts from the Simpson post base to take each one down for sawing.

This project is continued in Deck Stair Landing: Saw Post-to-Beam Support Notches.

Take care,

Bob Jackson

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