This project explains how to build a deck rail from scratch using pressure treated lumber and mount the rail on a concrete patio using concrete wedge anchors.
Deck Rail Installation Overview
The house sits on a hillside and the basement level concrete patio lacked a deck rail, giving the house an unfinished look. I built a 25 inch high deck rail from scratch using pressure treated lumber and corrosion resistant wood screws. At 25 inches high the deck rail is low enough such as not to block the view, just right for sitting on and high enough to keep my dogs taking shortcuts through landscaping. The 4×4 end posts are mounted on 1/2 inch threaded concrete anchors and tied into the main 8×8 deck supports as shown here. The deck rail was painted with a redwood stain:
The end view of the deck rail illustrates the 4×4 end post, 2×4 cap and face board construction technique. Note the Simpson Strong-Tie CPS4 black plastic post standoff at the bottom of the 4×4.
Building Code Compliance
A deck rail is required is required when the deck (or concrete slab in this case) is 30 inches or more above grade (ground level). My basement slab varies from even with the ground to a foot or two above grade so a guardrail isn’t required by code. See How to Build a 2×6 Porch Rail and How to Build Code Compliant Deck Railing if you need a full height compliant guardrail.
How to Build a 2×4 Deck Rail on a Concrete Patio
The deck rail enclosed most of the concrete patio, except for a ~4 foot gap between the house and the deck stairs as shown below. My dogs would run through here and mess up the pine straw. Here’s how I built a deck rail section to close the gap.
Jumping ahead – here’s the finished deck rail, ready to be stained when the weather warms up. Not the gap between the house wall and the deck rail so there’s space to paint the wall but not so narrow as to catch leaves. A ~2 inch gap between the bottom rail and concrete patio provides room for leaves to pass under when using the leaf blower.
Deck Rail Building Materials
The materials for this project are:
- Pressure treated 4″x4″x8′ posts
- Pressure treated 2″x4″x8′ boards
- Pressure treated 2″x2″x8′ boards for balusters – I space my baluster 3-1/2 inches apart
- Concrete wedge anchors – 1/2 inch diameter by 5-1/2 or 6 inches long
- Simpson Strong-Tie CPS 4×4 plastic post standoffs
- 3-1/2 inch and 2-1/2 inch corrosion resistant deck screws
You’ll need to measure and figure up the quantity of lumber and supplies necessary for your particular project. I begin by making a free hand drawing of the layout and measurements. Next I total up the materials to prepare a shopping list. Keep in mind how the lumber will be cut to minimize waste. It may be better to use 10- or 12 foot lengths of lumber for less waste and/or fewer joints.
The materials for this small project are laid out below after measuring and cutting the lumber:
Build the Deck Rail
I started by cutting the 4×4 end posts to 21 inches in length using a Dewalt Miter Saw. I can’t say enough about how useful a power Miter Saw is for making quick precise cuts at different angles. The usual statements apply when working with a power saw – be careful our you’ll loose a finger! – and wear safety glasses. I always do. Honest.
The balusters are marked off at 19 inches in length on a 2x2x8 square post. At 19 inches long, I can get five (5) complete balusters from an 8 foot (= 96 inches) post with only 1 inch of waste: 19 * 5 = 95 inches.
The seven (7) balusters I needed are cut to 19 inches long:
The balusters start out with square flat ends. The miter saw is set to 35 degrees as shown below. The bottom end of the baluster will be cut at a 35 degree angle to form a drip edge to encourage water runoff. If the bottom end were left flat, water would tend to pool and encourage rot.
The miter saw blade is lowered with the motor off to position the blade before making the cut. I like to leave a 1/4 wide lip so as not to weaken it with sharp point. The baluster end profile will be a “blunted cheese wedge”.
Profile view of the baluster drip edge. Click on the image for a full size image.
The finished stack of balusters showing the bottom angle and drip edge.
This project is continued in How to Build a 2×4 Deck Rail on a Concrete Patio – Part 2.
Thanks for reading!
Bob Jackson
