This project is continued from Part 1.
Setting the Concrete Anchors for the 4×4 Posts
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:
- Locate the right post and mark the center as shown below.
- Measure 39-1/2 inches to the left and mark the center of the other post.
- Drill 1/2 inch holes with a hammer drill for the concrete wedge anchors.
Drilling the Hole for the Concrete Anchor
I used 1/2 inch x 5-1/2 inch threaded concrete anchors as shown. I bought mine from Home Depot.
Red Head - Trubolt Concrete Wedge Anchor
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
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.
Drilling the Hole and Checking the Depth
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 overkill for the job.
Setting the Concrete Anchors
Place the washer and nut on the anchor and tighten. The anchor should grab fast with almost no slippage.
Tightening the Concrete Anchor
The concrete wedge anchor is set fast and tight:
Concrete Wedge Anchor
Setting the 4×4 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:
Measure 1-3/4 Inches to Locate the 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.
Mark a Line at 1-3/4 Inches per Side
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.
4x4 Center Located
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.
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.
Trial Fitting the Concrete Anchor
Place the post standoff over the pin to check the overall fit and assembly:
Fitting the Post Standoff
The post standoffs are attached with four 2-1/2 inch corrosion resistant deck screws as shown.
Fasten the 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.
Trial Fit the Post on the Anchor Pin
This project is continued in Part 3.
Thanks for reading!
Bob Jackson
May 6th, 2010 at 11:09 am
Hi, nice write up! I have a question. I am redoing my front porch railing. The porch is concrete bordered by two rows of brick. I need to attach the railing 4×4 post on the brick between my main porch support posts. The original 4×4′s were just glued in place and provided no lateral stability and have long since came loose. I understand that i cant use wedge anchors in brick, so what options do i have? Would it be best to just insert a threaded rod in a chemical fastener and install as you outlined above or are there other options that would be better such as a single expansion anchor Thanks.
May 6th, 2010 at 6:44 pm
> … would it be best to just insert a threaded rod in a chemical fastener …
That sounds reasonable. Choose your anchor, drill a hole through the brick (not the mortar joint) and set the anchor with Simpson Strong-Tie(R) epoxy anchoring adhesive. The Simpson Strong-Tie products are available at the big box home improvement stores. Choose a longer anchor – say 8″ or even 10″ long – to better distribute the load through the brick.
The Simpson Strong-Tie site has a nice graphic for setting anchors in brick.
> or are there other options that would be better such as a single expansion anchor
An expansion, or wedge anchor, would crack the mortar joints and split the bricks. You’re thinking is correct that wedge anchors shouldn’t be used with brick.
Thanks for reading,
Bob Jackson
May 7th, 2010 at 6:20 am
Thanks for the prompt feedback, it is much appreciated!