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A completed step for a deck

Overview

If there’s a big gap between your back door and your backyard, you may want to add a step to your deck. Here's how to build one.

Tip: This guide works best with soil or grass on the surface, as it requires digging holes for your stumps.

Safety tip: Always wear the appropriate safety equipment (safety glasses, ear muffs and a mask, for example) and always follow the instructions for the product or equipment.

Steps

1Measure and mark

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. 

A spot being marked for a post hole

2Dig the holes

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.  

Holes for stumped being dug

3Cut and paint the stumps

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

Green Bunnings hammer
Tip: Make sure you’re wearing gloves for this part, as it could get messy.
Stumps being painted with pitch

4Mix and pour concrete

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. 

Concrete being poured into a stump hole

5Backfill with soil

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.

Stump hole with a stump having been backfilled with soil

6Work out the height

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.

Green Bunnings hammer
Tip: Keep in mind that the minimum height of a step is 140mm, with the maximum being 190mm.
A Bunnings team member checking the height of a stump for a step

7Cut the stumps

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

Stumps being cut to the ideal height

8Check out the posts

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.

Excess wood being chiselled away from a stump

9Mark out the joists

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.

Position for joists being marked out on a deck

10Build the subfloor

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.  

A subfloor being assembled by a Bunnings team member

11Screw the joist into place

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. 

A subfloor being screwed into place on a deck

12Measure boards

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.

a subfloor being measured and marked for boards

13Cut to size

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

Lengths of timber being cut for decking boards

14Lay decking boards

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.

Decking boards being laid into place

15Add wedges and line up

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. 

Wedges being added between laid boards to ensure even spacing

16Pre-drill and drill into place

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

Decking boards being drilled down onto the subfloor

17Cut overhang

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

Green Bunnings hammer
Pro tip: Use a circular saw or hand saw for a clean edge.
Overhanging lengths being cut from the secured decking boards

18Attach screening

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. 

Screening being attached to the step

19Protect your deck

Giving your deck a new coat of stain is the best way to preserve the timber and keep it looking fresh. Here’s our handy guide on how to stain a deck.

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More D.I.Y. Advice

Health & Safety

Asbestos, lead-based paints and copper chromium arsenic (CCA) treated timber are health hazards you need to look out for when renovating older homes. These substances can easily be disturbed when renovating and exposure to them can cause a range of life-threatening diseases and conditions including cancer. For information on the dangers of asbestos, lead-based paint and CCA treated timber and tips for dealing with these materials contact your local council's Environmental Health Officer or visit our Health & Safety page.

When following our advice in our D.I.Y. videos, make sure you use all equipment, including PPE, safely by following the manufacturer’s instructions. Check that the equipment is suitable for the task and that PPE fits properly. If you are unsure, hire an expert to do the job or talk to a Bunnings Team Member.