Planning a renovation in Adelaide? Before you start choosing tiles and kitchen benchtops, there’s a question that could save you tens of thousands of dollars: is your foundation up to the job?

Renovating a home with foundation problems is like painting over rust — it looks good for a while, then everything starts falling apart. At ADL Underpinning, we work with Adelaide homeowners and builders to ensure foundations are solid before renovation work begins, so your investment is protected for the long term.

Why Foundation Assessment Matters Before Renovating

Many Adelaide homes — especially those built before the 1990s — sit on foundations that are barely adequate for their original design, let alone the additional demands of a renovation. Here’s why this matters:

Existing cracks will get worse — renovation work (demolishing internal walls, adding weight, changing load paths) puts additional stress on a foundation that’s already struggling
New work will crack too — brand-new plaster, tiles, and paintwork will crack within months if the underlying foundation continues to move
Builder’s warranty won’t cover it — if foundation movement damages renovation work, the builder isn’t liable for pre-existing structural issues
It’s cheaper to fix first — underpinning before renovation is almost always cheaper than underpinning after, because access is easier and there’s no finished work to protect or repair

Common Renovation Scenarios That Need Underpinning

Kitchen and Bathroom Renovations

These are Adelaide’s most popular renovations — and the ones most affected by foundation problems. Uneven floors mean cabinets don’t sit level, benchtops don’t align with walls, and tiles crack at stress points. If your floors slope or bounce, underpinning first saves you from expensive rework later.

Open-Plan Conversions

Removing internal walls to create open-plan living changes how loads are distributed through the foundation. If the foundation was marginal before, removing load-bearing walls and concentrating forces onto fewer points can trigger new settlement. A structural engineer should assess both the wall removal and the foundation capacity.

Extensions and Additions

When you add to an existing home, the new section and the old section will have different foundations. If the existing foundation is already moving, the junction between old and new will crack — sometimes dramatically. Underpinning the existing foundation before building the extension prevents this. See our dedicated extensions underpinning page for more detail.

Heritage Home Renovations

Renovating a heritage home in Adelaide’s inner suburbs almost always reveals foundation issues that were hidden behind old wall linings and floor coverings. It’s common to discover that the original bluestone or rubble footings are barely 200mm deep — far too shallow for Adelaide’s reactive clay.

Sub-Floor and Under-House Conversions

Converting a sub-floor space into a usable room adds load to the existing footings and may require excavation that undermines them. This is specialised work that often requires underpinning as part of the conversion. See our basement excavation page.

When to Underpin — Before, During, or After Renovation?

Before renovation is almost always best. Here’s why:

Access is easier — no new cabinetry, tiles, or finished surfaces to work around
Cost is lower — no risk of damaging completed renovation work
Timeline is cleaner — underpinning is done and certified before the builder starts
Peace of mind — you know the foundation is solid before investing in the fit-out

The exception is when foundation issues are discovered during renovation — perhaps hidden behind wall linings or revealed when floors are stripped. In that case, work should pause until the foundation is assessed and any necessary underpinning is completed.

Our Process for Renovation Underpinning

Pre-renovation inspection — our partner contractors assess the existing foundation condition, identify any movement or damage, and review your renovation plans to understand what additional loads or changes are proposed
Engineering coordination — we work with your structural engineer (or recommend one) to design underpinning that accounts for both existing problems and the renovation’s new requirements
Underpinning works — foundation stabilisation is completed before the builder starts, or coordinated with the build schedule if staging is needed
Certification — the engineer certifies the completed underpinning, giving you and your builder confidence to proceed with the renovation
Builder handover — our partner contractors provide all documentation to your builder so they understand what’s been done and can plan their work accordingly

Methods Our partner contractors use for Renovation Projects

Screw piles — fast, low-vibration, minimal disruption to the existing building. Often the best choice when timing is important
Resin injection — ideal for slab levelling before new floor finishes are installed
Mass concrete — cost-effective for straightforward stabilisation with good access
Beam and base — for major renovations that significantly change the building’s load profile

Renovation Underpinning Costs

Costs depend on the extent of foundation work needed and the chosen method:

Localised repair before reno (one area, minor movement): $3,000–$10,000
Standard residential (perimeter stabilisation): $10,000–$30,000
Major renovation prep (full underpinning + load upgrade): $30,000–$60,000+

Compare this to the cost of repairing a brand-new renovation after foundation movement — cracked tiles ($5,000+), buckled cabinetry ($10,000+), replastering ($3,000+). Prevention is significantly cheaper than cure.

For a detailed estimate, visit our cost guide or request a free quote.

Planning a Renovation? Check Your Foundation First

The smartest time to address foundation problems is before you spend money on a renovation. Email us at chris@adlunderpinning.com with photos of any cracking or unevenness, plus a brief description of your renovation plans. We’ll assess the foundation and let you know whether underpinning should be part of your renovation budget — or if your foundation is solid and you can proceed with confidence.

Underpinning for Renovations Adelaide