Foundation FAQs: Answers to the Most Common Questions
A quick-reference collection of the most common questions we hear about foundations, with links through to the full guides for more detail.
Soil and Classification
Your site’s classification under AS 2870 — see our site classification guide — is determined by a soil report and drives almost every foundation decision. See our how soil type affects your foundation guide for the full picture.
Slab Systems
Waffle slabs and raft slabs are the two most common systems — see our full comparison for how the choice between them is made based on your soil report.
Deep Foundations
Where standard slabs aren’t suitable, bored piers or screw piles are used — see our comparison guide for how this decision is made.
Engineering and Compliance
Every compliant foundation needs an engineer-certified design and, for house slabs, a building permit. See our foundation design 101 guide for the complete process from soil report to certified design.
Recently Completed Projects
We complete residential and commercial concrete, excavation and foundation projects across Melbourne every week. Explore our project gallery to see the range of work we deliver.
Frequently Asked Questions
How do I know what foundation system my home needs?
It’s determined by your site’s soil classification from a soil report, certified by your structural engineer — not a preference-based choice.
Is a soil report always required?
Yes, for compliant residential foundation design in Victoria — it’s the essential input your engineer needs.
What's the difference between a waffle slab and bored piers?
A waffle slab is a slab-on-ground system tolerant of reactive soil movement; bored piers are deep footings bypassing problematic surface soil entirely — used for different site conditions.
Does every foundation need a building permit?
New house slabs always do; other foundation work depends on specific scope, worth confirming with a building surveyor.
Can I choose my own foundation system?
No — it’s determined by engineering assessment of your site’s soil and your building’s loads, not personal preference.
Related Guides, Calculators & Services
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