How to Build a 2×4 Deck Rail on a Concrete Patio: Drill 1/2 inch holes in the concrete patio, install concrete wedge anchors, 4×4 post standoffs and mount the posts. This project is continued from How to Build a 2×4 Deck Rail on a Concrete Patio – Part 1.

Install 4×4 Post Concrete Anchors

The centers of the posts are marked with a + on the concrete as shown near the drill bit. In my case the deck rail is 43″ long. A 4×4 post is actually 3.5 inches x 3.5 inches. To find the distance between the post centers I subtract 1/2 width of each post, or 1-3/4 inches:

43 inches total width minus 1-3/4 inches (left post) minus 1-3/4 inches (right post) = 39-1/2 inches distance between the post centers.

To mark the post centers:

  1. Locate the right post and mark the center as shown below.
  2. Measure 39-1/2 inches to the left and mark the center of the other post.
  3. Drill 1/2 inch holes with a hammer drill for the concrete wedge anchors.
Build a Deck Rail: Drill the Hole for the Concrete Anchor

Build a Deck Rail: Drill the Hole for the Concrete Anchor

I used Red Head 1/2 inch x 5-1/2 inch threaded concrete anchors purchased at the home improvement store:

Red Head - Trubolt Concrete Wedge Anchor 1/2" x 5-1/2"

Red Head – Trubolt Concrete Wedge Anchor 1/2″ x 5-1/2″

Concrete wedge anchors have a metal sleeve on the tapered bottom end that grabs tight when the anchor is pulled against the hole by the threaded nut. These anchors work extremely well.

Red Head - Trubolt Concrete Wedge Anchor

Red Head – Trubolt Concrete Wedge Anchor

The concrete anchors must be set at least 2-1/4 inches deep. Drill the hole about 1 inch deeper (or 3-1/4 inches total) to allow for dust accumulation at the bottom of the hole.

Build a Deck Rail on a Concrete Patio: Check Hole Depth for Concrete Anchor

Build a Deck Rail on a Concrete Patio: Check Hole Depth for Concrete Anchor

Mark the minimum depth line on the anchor (blue line) and tap the anchor into the hole. The 3-1/2 lb sledge hammer as shown here is more than enough for the job.

Build a Deck Rail on a Concrete Patio: Install the Concrete Anchor

Build a Deck Rail on a Concrete Patio: Install the Concrete Anchor

Place the washer and nut on the anchor and tighten. The anchor should grab fast with almost no slippage.

Build a Deck Rail: Concrete Anchor Bolt for the 4x4 Post

Build a Deck Rail: Concrete Anchor Bolt for the 4×4 Post

The concrete wedge anchor is set fast and tight:

Build a Deck Rail: Concrete Wedge Anchor

Build a Deck Rail: Concrete Wedge Anchor

Install the 4×4 Deck Rail Posts

Drill a 1/2 inch hole in the bottom of the 4×4 posts to slide the post over the anchor pin.

Locate the center of the post by measuring and marking 1-3/4 inches on each side as shown by the black tick marks:

Build a Deck Rail: Measure 1-3/4 Inches to Locate the 4x4 Post Center

Build a Deck Rail: Measure 1-3/4 Inches to Locate the 4×4 Post Center

Use a square to mark a straight line across the tick marks on each side to locate the center of the 4×4 post.

Build a Deck Rail: Mark a Line at 1-3/4 Inches per Side of 4x4 Post

Build a Deck Rail: Mark a Line at 1-3/4 Inches per Side of 4×4 Post

The center of the 4×4 post is now located at the cross hair to drill the 1/2 inch hole to receive the pin of the concrete anchor wedge.

Build a Deck Rail on a Concrete Patio: Center of 4x4 Post Marked

Build a Deck Rail on a Concrete Patio: Center of 4×4 Post Marked

Drill a 1/2 inch diameter hole in the center of the post to receive the pin of the concrete anchor. I use Dewalt “pilot” type drill bits that prevents the large drill bit from “walking” when starting the hole. Drill the hole about 4-1/2 inches deep.

Take care to drill the hole vertical (i.e. not canted to the side). I use the carpenters square to periodically check my drill alignment with the post.

Build a Deck Rail: Drill a 1/2 Inch Hole for the Concrete Anchor

Build a Deck Rail: Drill a 1/2 Inch Hole for the Concrete Anchor

Test fit the anchor wedge to verify the hole is deep enough and the hole is vertical with the post.

Build a Deck Rail: Trial Fit the Concrete Anchor

Build a Deck Rail: Trial Fit the Concrete Anchor

Place the post standoff over the pin to check the overall fit and assembly:

Build a Deck Rail on a Concrete Patio: Post Standoff and Concrete Wedge Anchor

Build a Deck Rail on a Concrete Patio: Post Standoff and Concrete Wedge Anchor

The post standoffs are attached with four 2-1/2 inch corrosion resistant deck screws as shown.

Fasten the 4x4 Deck Post Standoff with Screws

Fasten the 4×4 Deck Post Standoff with Screws

Set the 4×4 post on the concrete anchor pin to check the overall fit. Repeat for the above procedure for the other post.

Build a Deck Rail on a Concrete Patio: Set the Post on the Anchor Pin

Build a Deck Rail on a Concrete Patio: Set the Post on the Anchor Pin

This project is continued in How to Build a 2×4 Deck Rail on a Concrete Patio – Part 3.

Thanks for reading!

Bob Jackson

Copyright © 2017 HandymanHowTo.com   Reproduction strictly prohibited.