Project Overview

It’s important to install your outdoor decking safely and securely with a strong foundation. We’ll show you how to dig the holes for your stumps, join the bearers then concrete in your stumps. 
Continue to step-by-step instructions
This D.I.Y. Advice is part of a series How to build a deck

Step by Step Instructions

1 Dig the holes for the stumps
2 Have the holes inspected
3 Join the bearers together
4 Measure the height for the bearers
5 Mark the check-out on the bearer
6 Cut the check-out
7 Level and support the bearer
8 Drill the holes for the stumps
9 Secure the stumps
10 Concrete in the stumps
11 Install the other bearers and stumps
12 Back-fill the holes
  • Step 1. Dig the holes for the stumps

    Dig the holes for your stumps using the marks you made with string lines, which we covered in another video. The holes must be dug to depths according to your plans and permits. The sides of the holes must be straight and clean at the top.

  • Step 2. Have the holes inspected

    After digging all of the holes to the right depth, organise an inspector to come and check them out before you start inserting the stumps.
  • Step 3. Join the bearers together

    After your bearers are cut to size, you’ll need to join two together. Run a bead of glue down the length of one bearer. Place it on top of the other bearer and line them up so they’re flush. Use the nail gun to join the two bearers. Make sure the nails go in on a slight angle, as this will give them better holding power. Turn the bearers over and nail the other side as well.

  • Step 4. Measure the height for the bearers

    Run a spirit level from the existing timberwork to the brickwork. With a level reading, measure the distance between the spirit level and the brickwork. This will be the size of the check-out you need to make.
  • Step 5. Mark the check-out on the bearer

    Use the check-out measurement you made and mark it on the end of a bearer. Make sure you also use a set square to mark the depth and length of the check-out. This check-out will give your decking extra support over the brickwork.

  • Step 6. Cut the check-out

    Use the circular saw to cut along the length of the bearer check-out. Then to cut across the bearer. Make sure you set the correct depth on your circular saw so you don’t overcut your markings. Use a hammer to remove the check-out from the bearer. Then use the chisel to make it level. 

  • Step 7. Level and support the bearer

    Place the bearer on the brickwork. At the other end of the bearer, place a support post on a flat, hard surface. Making sure the bearer is level, mark its height on the support post. Use the nail gun to secure the bearer to the support post. Place another support post on the other side of the bearer and secure it with the nail gun. Use the spirit level to make sure it’s still straight.

  • Step 8. Drill the holes for the stumps

    Drill into the bearer in the central point above the hole you have made for each of the stumps. The hole in the bearer is for the threaded rod stump. 
  • Step 9. Secure the stumps

    Put ant capping on top of the stump and then have someone help you insert the stumps into the holes. Lift the stump so the threaded rod goes through the hole in the bearer. Place a washer and nut onto the rod and tighten with a spanner to securely suspend your stump. Check that the bearer is still level after you’ve attached the stump.

  • Step 10. Concrete in the stumps

    Mix the concrete in a wheelbarrow. Then fill in your hole with concrete around the stumps up to the required height.  

  • Step 11. Install the other bearers and stumps

    Now repeat the previous steps to join, install and secure the other bearers and stumps for every hole that you’ve dug.

  • Step 12. Back-fill the holes

    You’ll need to leave the concrete around the stumps to harden overnight. Then use a claw hammer to remove all of the support posts on the bearers. Back-fill all of the holes with soil. Then you can tidy up your work site and you’re ready to install your joists.

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Health & Safety

Please make sure you use all equipment appropriately and safely when following the advice in these D.I.Y. videos. You need to be familiar with how to use equipment safely and follow the instructions that came with the equipment. If you are unsure, you may feel it is safest to consult an expert, such as the manufacturer or an expert Bunnings Team Member.

Grave health hazards are linked to asbestos, which may be in homes built up to 1990. Health hazards may result from exposure to lead-based paints in older materials and copper chromium arsenic (CCA) treated timber. 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. You can also use a simple test kit from Bunnings to indicate the presence of lead-based paint Test.
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