How to add a step to your deck

The first thing we need to do is measure and mark out where our stumps will go. Use a tape measure to measure the preferred length of your step and mark the spot with spray paint. Repeat this process down the length of your deck. 

Now it’s time to dig the holes for each stump. Use a shovel (or mattock if the soil is hard) and begin digging a hole 300mm deep and 300mm wide at each point.  

Cut the stumps and paint them thoroughly with heavy-duty bitumen paint. This will ensure the timber doesn’t rot. Leave to dry.

Using a wheelbarrow or bucket, mix your concrete mix with water as per instructions. Working on one hole at a time, pour the concrete halfway and then jiggle your stump in, checking to ensure it’s level before adding the rest of the concrete. 

Once the stump is lined up and level, backfill each hole with soil right to the top so it’s level with the ground. Let it set overnight.

To work out the height of the step, use a tape measure to measure the height from the top of the joist to the ground. Divide this number by two, and then subtract the height of your subfloor. This will give you the height of your stump.

Mark this on each stump with a permanent marker.

Cut at the mark one side at a time using a circular saw.  

To check out your post, measure and mark the depth and thickness of your timber. In this case, ours is 140mm x 45mm, so we’ve measured 140mm from the top of the stump and set the saw to 45mm. From there, it’s a case of sawing through the stump in increments to create a bracket for your timber. You may need to use a chisel or hammer for a cleaner finish.

It’s important to keep the joist spacing the same on your step. To do this, sit your outside beam up on the deck and mark the existing joists.

Now it's time to build the subfloor with joists. Using our marked joist, we’re going to attach smaller joists to create a ladder. From here, we’ll attach a longer piece of timber to create the subfloor. Once it’s assembled, drop it on top of your stumps. It should fit easily into each bracket.  

To complete the subfloor, it’s time to screw it into place. If you can, have someone help life the joist in place and then begin screwing. Make sure you keep checking it’s level with a ruler along the way. For further support, you can also screw in joist hangers into each corner using a drill, and screw into place. 

Measure the length of your steps so you know the measurements for your deck boards. Make sure you add 20mm on either side for overhang.

Mark out the required length on each of your intermediate boards. Cut to size using a mitre saw. 

Lay the boards for your step. Begin with the outside board first, ensuring it has the correct overhang, and then work your way in. You can place an offcut on the screening to make you’re your overhang is correct. Keep in mind that you may need to cut one of the boards, depending on the width of the step and the boards you’re using. Pre-drill and then drill the first board using decking screws.

Once the outside board is secure, place your remaining boards on your step. Place a wedge between every board – this will help space the deck evenly.  

To ensure your screws are in line, use a chalk line to mark out lines down the length of your step. 

Starting with the side perpendicular to your deck, pre-drill holes at every joist and then use screws to secure each board. 

Saw off the edges of your step so that they are even. 

Place the screening closest to the outside board on the step and fix into position using wedges. Pre-drill and then screw into place. You may need to use a clamp to keep it in place while you drill.

There you have it! An easy access point for your deck and a great solution when your back door isn’t level with your backyard.