The key to a durable and long-lasting deck lies in the care and attention given to assembling its substructure. Here is everything you need to know about installing stumps.
First, check your height to ensure you have enough clearance between the ground and your bearer. If you don’t have enough clearance, you may need to dig out some soil. A good shovel, pick and wheelbarrow will come in handy here.
Mark out where the stumps need to go. To determine the stump and bearer positions, always refer to timber-stand tables. If you’re building a deck on top of a concrete slab, use adjustable decking feet (i.e. builders feet) instead of stumps.
Once you’ve marked out where the stumps need to go, you’re ready to dig holes for your stumps. Make sure the depth of your hole is founded at least 100mm into stiff clay. A good rule of thumb is that holes should be around 300 x 300 x 600mms deep; however, depths will vary depending on your location.
Before placing the stumps into the holes, apply a coat of bitumen paint to ensure the timber doesn’t rot. Allow to dry.
While the paint is drying, mix the concrete. You’ll need enough to fill each hole at least halfway. You’ll want at least a minimum of 150mm of concrete beneath your stump for support.
Fill each hole halfway with concrete and place your stumps into the holes in-line with your string line. Check your stumps are straight using a level. Replace the soil in each hole and leave to set overnight.
Once the concrete is dry, mark the stumps off and cut them to your desired height.
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.