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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.
Person marking outer edge of trench for concrete footings.

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.
Person digging trench for concrete footings.
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.