Composite Deck

Installing An Outdoor Staircase For Your Deck

So long as you have the right tools in the shed and a determined approach to DIY projects, you’re already halfway to installing your first flight of deck stairs.

Now all you need is a bit of elbow grease and some time in which to complete the project, and you’ll be walking up and down those steps in no time at all.

This is a guide that instructs you step-by-step (please excuse the pun) on how to install your own deck stairs.

However, it should be noted that before you read on or commence building that you should check with the local council to make sure your stairs comply with any rules and regulations regarding the construction of structures in and around residential premises.

A Quick Overview

When finished, deck stairs usually descend from an upper platform (the deck) to a lower platform (a concrete pad).

The most conventional set up is to install two or three stringers, spaced about a foot apart from the others. They are hitched or fastened onto the deck and slant diagonally from the lip of the deck to rest on the concrete pad below, thereby connecting the upper platform to the lower.

You can purchase cookie-cutter stringers from your local hardware store or create your own from scratch, but they should always have a zigzag shape cut out of their topside.

Once you have installed them, with the zigzag cut-out facing upwards, it is simply a matter of mounting your lengths of timber or composite deck flat across the top of them in a horizontal fashion. This will create the steps which you will use to ascend and descend your staircase.


Got the big picture? Good! Now it’s time for a more detailed 5-Step Procedure to get that staircase in its place!

Step 1. Whip out your tape measure or long level and measure it vertically against the lip of your deck down to the landing platform to figure out the required height for your staircase.

This height will determine how many steps you need to install and how far apart you should space them along your stringers.

To figure out these calculations, you should divide the total length of your height measurement by 18cm as this is the average height of an outdoor step in Australia. This will give you an indication as to how many steps you’ll need for the finished product, keeping in mind that the deck itself will serve as the final step onto the landing.

Step 2. Install a lower platform, usually in the form a concrete pad.

To do this, you should form a simple frame with two-by-fours in which you will pour your concrete, keeping in mind that your pad should be wider than the steps you will install. Flatten out the earth inside the frame as best you can, using a level to make sure the surface is even.

You should then mix and pour your concrete into the frame. Always comply with the manufacturer’s instructions when completing the concreting process of this project.

Step 3. While your concrete is hardening up, you should cut your stringers (unless you’re purchasing them from a hardware store or outlet, in which case they will be pre-cut for your convenience.)

If not, you should use a right-angled framing square to sketch the outline of your steps onto your board before you cut it into that zigzag shape we were talking about earlier.

To make sure you cut the correct number of steps out of your stringer, refer to the calculations you rustled up when completing Step 1.

Once you have completed the first stringer, you can use it as a template. Clamp it onto your second stringer and trace around it to create an identical outline, then cut this one out too, repeating the process again if you need a third.

(Note: always use a circular saw if you’ve got one handy for this part of the project as it will ensure the cleanest edges and best results.)

Step 4. Create a support board that is the same width as your steps. Secure it to the deck using long decking screws or joist hangers.

Following this, you should attach a hanger to your stringer(s) and mount it onto the support board you just installed, using wood screws to fasten it into place, and repeat to secure the hanger to the inner side of the stringer(s).

At all stages of this step, you should use a level to make sure you are maintaining an even surface at all times, thereby ensuring that the steps will align with the upper deck.

If you wish, you can install anchors on the concrete landing pad. The lower ends of your stringers will slot into these and be fastened into place to further secure and stabilise the staircase.

And finally… Now it is time to simply cut the treads (the lengths of timber or composite that will serve as your steps) and mount them in a horizontal fashion across your stringers, making sure they span all stringers, and are secured firmly into place. Superdeck’s composite deck can be used for the treads on your deck. Superdeck’s composite deck doesn’t require a lot of maintenance and its durable surface is perfect for usage on stairs.

And now…

Now that you’ve put the above guide into action, you should have a set of deck steps safely installed, giving you passage from the upper platform of your deck to a landing pad.

You can now make your steps flashier by adding in rails and toe kicks, or whatever else you like.

Enjoy the new steps!