Restumping (or reblocking) replaces the stumps under a house built on posts. Underpinning strengthens and deepens the footings beneath a slab or brick wall. They solve different problems, and choosing between them starts with an engineer diagnosing why the building is moving — not with picking a repair method.
If your floors slope, doors stick or walls have cracked, here's how the two options differ and where structural engineering fits in.
What is restumping (reblocking)?
Older Melbourne homes — weatherboards and many period houses — sit on stumps rather than a concrete slab. Over decades, timber stumps rot, suffer termite damage or sink as the soil moves, and the floor above goes with them.
Restumping replaces those deteriorated stumps with new ones, typically concrete or galvanised steel, restoring a level, stable base. It's the usual solution for a house on raised footings where the stumps themselves have failed.
What is underpinning?
Underpinning applies where a house sits on a slab or strip footings and the footing has moved — usually because the ground beneath it has. The repair extends or strengthens the existing footing down to more stable founding material, so the structure is supported by ground that won't keep moving.
Underpinning is also used when you're adding load to an existing building — a second storey, for example — and the original footings weren't designed for it.
How do you know which one you need?
This is the important part: the visible symptoms are often identical. Sloping floors, sticking doors and cracked walls can point to either problem — or to something else entirely, like reactive clay movement that may not need major repair at all.
Diagnosing the cause is an engineering question. It typically involves inspecting the structure, taking a levels survey to measure how much movement has occurred and where, and considering the soil conditions and drainage around the building. Only then can anyone say with confidence whether the stumps have failed, the footings have moved, or something else is driving it.
Getting this wrong is expensive. Restumping a house whose real problem is footing movement fixes the symptom while the cause continues.
Other methods you might hear about
Depending on the site and the cause, an engineer may specify approaches such as:
- Screw piles — steel piles wound into the ground to reach stable material below soft or reactive soil
- Bored piers — concrete piers cast into the ground for deeper support
- Resin injection — resin injected to fill voids and stiffen the soil, with less disruption on site
Each suits particular ground conditions. The right choice comes out of the diagnosis, not the other way around.
Where the structural engineer fits
To be clear about roles: a structural engineer diagnoses the cause and designs the remediation; a licensed contractor carries out the physical work. The engineer's involvement matters because:
- The cause must be identified before a repair is chosen
- The design must suit the soil, the loads and the structure
- Documentation and certification are generally needed for council and permit purposes
Our residential structural engineering team assesses foundation movement across Melbourne and designs the remediation — then your builder or specialist contractor executes it to that design.
Don't skip the drainage question
Many foundation problems in Melbourne trace back to moisture: broken stormwater pipes, poor surface drainage, or large trees drawing water from reactive clay. If the moisture cause isn't addressed, movement can continue even after a structural repair. A proper assessment looks at drainage and stormwater alongside the structure.
Noticed sloping floors or cracking? Talk to a Melbourne structural engineer for an assessment of what's actually causing it.
Frequently asked questions
What's the difference between underpinning and restumping? Restumping replaces failed stumps under a house built on posts. Underpinning strengthens or deepens existing footings under a slab or brick wall where the footing has moved.
Do I need a structural engineer for underpinning? Yes. An engineer diagnoses the cause of the movement and designs the remediation, and that design and certification is generally required for council and permit purposes.
How do I know which repair my house needs? The symptoms overlap, so it takes an inspection, a levels survey and an assessment of soil and drainage to identify the real cause. That diagnosis determines the repair.
Does underpinning need a building permit? Structural remedial work generally requires a building permit. Your building surveyor confirms the requirements for your situation.
Will the movement come back after repair? Not if the underlying cause is addressed. Where moisture or drainage is driving the movement, fixing the drainage matters as much as the structural repair.
