How to build patio stairs: expert tips and tricks

If you want to know how to build patio stairs, chances are you’ve succumbed to the lure of this backyard feature. In the summer, it seems that every outdoor space is punctuated by a well-placed and beautifully designed terrace. If you’ve decided to take on the task of building one yourself, you’ll know that it takes careful planning, a good understanding of math, and some confident DIY credentials.

While there are many elements that go into building a deck, mastering how to build deck stairs is probably one of the most important. The stairs will be used by anyone accessing the garden below and they should complement the overall look of your patio.

We asked the experts for their advice on how to build patio stairs, ensuring they meet basic safety standards and look good too.

How to build patio stairs

Before I tell you how, here are the basics of what you’ll need to build deck stairs. The easiest way to do this is with a kit, although of course you can start from scratch.

You will need:

  • Wood: 2 in x 6 in and 2 in x 12 in
  • decking screws
  • L-brackets
  • Stair stringers
  • Stair treads
  • chalk rope
  • Circular saw
  • Drill
  • hand saw
  • Spirit level
  • Safety glasses

1. Calculate the measurements of the deck stairs

“Stairs require a lot of math and an expert carpenter to make them,” says Steve Vanadia, president of Vanco Construction. (opens in a new tab).

The first thing you need to do is figure out where your stairs will end or where the landing point will be.

Lay a board from the top of your deck on the ground so you can start calculating the height of your stairs.

“In short, you divide the height from top to bottom by seven – this will allow for a very comfortable riser,” says Steve.

“Once you have that, you step out of the stringer with a rafter square and leave an 11-inch tread between each step,” Steve adds. You can also use an online tool, which can help you calculate all these measurements.

2. Assemble the deck stairs

Start assembling your deck stairs by screwing the stair stringers to the bottom of the deck frame. Use L-brackets and long screws to secure the stringers to your deck.

Next, you will need to cut the risers to fit the stringer. Place a riser against the edges of the stringers outward and draw guidelines where the riser needs to be cut to fit.

Use a circular saw to trim the riser, cutting along the guidelines until you cut the entire board. Repeat the process until all the risers have been cut to size. Then attach the risers with 3-inch deck screws. Finally, cut the steps and drill them into the staircase.

3. Add a handrail

Once you’ve completed your stairs, you’ll want to consider adding a handrail. James Bruteon, CEO of sustainable building materials supplier, Envirobuild (opens in a new tab) advises you to check city codes and safety regulations before purchasing a pre-built handrail.

“There are standards for the height of the railings, the guardrails and the load capacity, because it could become real dangers,” says James.

If you are considering buying a pre-made handrail, remember that it can always be cut to size or adapted to make it work.

What is the formula for patio stairs?

The formula for deck stairs will help you determine the best number of risers to get from top to bottom. The formula is discovered by: measuring the height of your bridge in inches and dividing it by seven. If you get a whole number, add a riser; if you get a decimal number, round it down.

What is a deck stair stringer?

A deck stair stringer refers to the housing on each side of a staircase, into which the treads and risers are attached. You can buy pre-cut stringers at your local DIY store and measure their height and length.

If they are longer than necessary, you can cut them to size. To cut a stringer to the correct size, cut it from the bottom, regardless if the bottom step is not as high as the others.

There are other parts of the staircase that you will also need to be aware of. “Stair treads are the horizontal boards that you walk on and risers are the boards installed at the ends to cover vertical spaces,” confirms a spokesperson for the Decks.com online support service. (opens in a new tab).