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How to dig a foundation

An orange paint spray can being used to mark bare earth for a foundation dig site

Overview

A lot of structures are built on top of concrete footings. If you can dig the trenches for those footings, you are well on your way to laying your own foundations. We'll show you how to properly mark out and dig the trenches for concrete footings.

Steps

1Mark the outer edge of the trench for your concrete footings

To position the outer edge of your footings correctly, get a building surveyor to place survey pegs and a string line for you. Then use line-marking paint to transfer that line onto the ground.

Once the line is painted, remove the string and you are ready to dig.

Green Bunnings hammer
Pro tip: don't do this when it's raining.
An orange paint spray can being used to mark bare earth for a foundation dig site

2Dig the trench for the concrete footings

Keep inside the painted line while digging your trench. In this case the plans call for a trench that is 400mm wide. Our shovelhead is 200mm, so we use that as a guide to measure the width of our trench as we go. Dig until your trench is as deep as your plans require. Then use the blade of your shovel to neaten up the trench walls. Once the trench is finished, get the building surveyor back to approve it and you are ready to pour your concrete footings.
A shovel being used to dig into earth for a foundation

3Looking to add concrete?

If you want to move onto next steps follow our guide on how to mix concrete.
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.