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Home » House Exterior » Deck & Patio » How to Build a 2×4 Deck Rail on a Concrete Patio – Part 1

How to Build a 2×4 Deck Rail on a Concrete Patio – Part 1

Bob Jackson
Last Updated on
by Bob Jackson

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:

Deck Rail on a Concrete Patio
Deck Rail on a Concrete Patio

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.

Deck Rail Construction - End View
Deck Rail Construction – End View

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.

Deck Rail Gap between House and Deck Stairs
Deck Rail Gap between House and Deck Stairs

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.

Build a Deck Rail on a Concrete Patio
Build a Deck Rail on a Concrete Patio

Deck Rail Building Materials

The materials for this project are:

  1. Pressure treated 4″x4″x8′ posts
  2. Pressure treated 2″x4″x8′ boards
  3. Pressure treated 2″x2″x8′ boards for balusters – I space my baluster 3-1/2 inches apart
  4. Concrete wedge anchors – 1/2 inch diameter by 5-1/2 or 6 inches long
  5. Simpson Strong-Tie CPS 4×4 plastic post standoffs
  6. 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 a Deck Rail: Materials Ready for Assembly
Build a Deck Rail: Materials Ready for Assembly

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.

Build a Deck Rail: Saw the 4x4 Posts with a Miter Saw
Build a Deck Rail: Saw the 4×4 Posts with a Miter Saw

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.

Build a Deck Rail: Measure Balusters on a 2x2x8 Square Post
Build a Deck Rail: Measure Balusters on a 2x2x8 Square Post

The seven (7) balusters I needed are cut to 19 inches long:

Build a Deck Rail: Balusters Cut to 19 inch Length
Build a Deck Rail: Balusters Cut to 19 inch Length

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.

Build a Deck Rail: Baluster Drip Edge to be Cut at 35 degrees
Build a Deck Rail: Baluster Drip Edge to be Cut at 35 degrees

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”.

Saw Deck Rail Baluster Drip Edge: Align the Blade
Saw Deck Rail Baluster Drip Edge: Align the Blade

Profile view of the baluster drip edge. Click on the image for a full size image.

Build a Deck Rail: Baluster Drip Edge Saw at 35 Degrees
Build a Deck Rail: Baluster Drip Edge Saw at 35 Degrees

The finished stack of balusters showing the bottom angle and drip edge.

Build a Deck Rail: Balusters Sawn with Drip Edge
Build a Deck Rail: Balusters Sawn with 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

balusterbasement patioconcrete anchorhow to build a deck rail on concretepatio deck rail
Bob Jackson
Bob Jackson
Technology product manager by day and a prolific handyman in the evenings and over the weekends. Bob was the founder of the original Handyman How To website and that tradition continues on this site with excellent new handyman content into the future.
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