Homeowners · Buyers · Builders
Underpinning in Hobart: independent advice, design and certification
Before anyone digs under your footings, find out whether underpinning is the right fix. We review underpinning quotes, design underpinning that any licensed builder can install, and inspect and certify it for your building surveyor. We never sell or install underpinning, so nothing rides on our answer.
Independent
We design and certify underpinning. We never sell or install it.
Fixed quote in 1–2 business hours
Get a fixed quote for underpinning advice
Send the underpinning quote or report you've been given, photos of the cracks and the suburb.
From $390 + GST. No obligation. Or call 03 6146 4747
In short
Underpinning deepens or strengthens a house's footings after they have moved. In Hobart, have the cause confirmed independently first: our underpinning quote second opinion starts from $390 + GST from documents and photos, and design and certification are a fixed quote per job. Underpinning is notifiable work in Tasmania, so it needs an engineer's design and a building surveyor.
- Fees
- Second opinion from $390 + GST; design by fixed quote
- Approvals
- Notifiable work: our Form 35 for your building surveyor
- Independent
- We never sell or install underpinning
Diagnosis first
Do you actually need underpinning?
Not always. Underpinning helps when a footing has lost support or sits on ground that will keep moving. Cracks caused by seasonal clay movement, a leaking pipe or a downpipe soaking a footing are fixed at the source, and they often settle once the water is controlled.
Clays weathered from dolerite are documented as expansive in Hobart, with Mineral Resources Tasmania reports from Lindisfarne, Lenah Valley and Taroona, so seasonal movement has to be ruled in or out first. That is why the cause should be confirmed by someone with nothing to sell before anyone prices house foundation repairs. Our crack and foundation report does that from $590 + GST.
A repair contractor
- Is paid when the underpinning goes in
- Usually offers one system
- May include its own engineering in the price
An independent engineer
- Is paid the same whatever the answer
- Chooses the method that suits the soil
- Designs it for any licensed builder to price
Four questions before you underpin
Has an independent engineer confirmed the cause?
Cracks alone don't prove a footing needs underpinning.
Yes: go to 2No: crack report firstHave leaks, downpipes and drainage been fixed?
Water is a common trigger for movement in reactive clay.
Yes: go to 3No: fix the water firstIs the footing still moving after that?
Monitoring through a wet and a dry period shows whether movement is ongoing.
Yes: underpinning may be justifiedNot sure: monitorHas a contractor already quoted?
Check the scope and method before you sign.
Yes: second opinionNo: we design it
Second opinion · from $390 + GST
What does an underpinning quote second opinion check?
An underpinning quote second opinion is a licensed engineer's review of a contractor's quote or report, from the documents and photos, to check whether the evidence supports the work and the scope is right.
- Does the evidence (crack pattern, levels, timing) point to footing movement, or to something else?
- Is the number and position of underpins matched to where the house has moved?
- Does the method suit the soil, the depth to firm ground and the cause?
- Does the price include engineering design, a Form 35, the building surveyor and stage inspections?
- Are the leaks, downpipes or drainage that caused the movement being fixed too?
- For contracts of $20,000 or more, does it follow the Residential Building Work Contracts and Dispute Resolution Act 2016?
Underpinning quote second opinion
A written opinion on whether the evidence supports underpinning, whether the scope and method make sense, and what to ask the contractor. If the documents can't answer the question, we say what would, such as an inspection or a soil test. Available anywhere in Tasmania.
Methods
Which underpinning method suits your house?
The underpinning method should follow the soil, the depth to firm ground and the cause of movement. This comparison reflects general engineering practice, not Tasmanian rules, and we don't sell any of these systems.
| Method | How it works | Often suits | Watch for |
|---|---|---|---|
| Mass concrete | Concrete cast in short sections under the existing footing, down to firmer ground | Strip footings under brick or sandstone walls, where firm ground is not too deep | Digging beside an old footing needs a set sequence; deep firm ground adds cost |
| Bored piers and beams | Holes drilled to firmer ground and filled with reinforced concrete, joined to the house by a beam | Deeper firm ground, or where a new beam is needed anyway | Drilling access, and how the beam connects to old footings |
| Screw piles | Steel piles screwed into firmer ground and tied to the footing with brackets or a beam | Tight access, or where little excavation is wanted | Corrosion protection, and proof each pile reached its design depth or torque |
| Resin injection | Expanding resin injected into the soil under the footing to fill voids, densify it and sometimes lift the footing | Voids or soft soil close under a footing or slab | It does not carry load down to deeper ground, so it may not suit deep reactive clay; the water source still needs fixing |
Three common underpinning methods, side by side
- 1 · Mass concrete: concrete is cast in short sections under the footing, down to firmer ground.
- 2 · Screw piles or piers: steel piles are driven or screwed to a firmer layer and tied to the footing with brackets or a new beam.
- 3 · Resin injection: expanding resin is injected into the soil under the footing to fill voids, densify it and sometimes lift the footing.
Design & certification · fixed quote
What does underpinning design and certification include?
Underpinning design and certification covers everything your building surveyor and builder need, from confirming the cause to signing off the finished work.
- Step 1
Confirm the cause
A site inspection, or our earlier crack report, establishes what moved and why.
- Where needed
Investigate the ground
A soil test to AS 2870, with boreholes by [geotechnical partner] where the design needs them.
- Design
Drawings and calculations
Underpin layout, depths, excavation sequence and details, plus our Form 35 for the building surveyor.
- During the work
Stage inspections
The engineer checks critical stages, such as excavations before concrete is poured.
- At completion
Certification
A certificate for your building surveyor that the work was built to the design.
Tasmanian rules
What approvals does underpinning need in Tasmania?
Underpinning is notifiable building work in Tasmania. The Director's Determination on categories of building work lists it as notifiable and notes it may need a site and soil test to AS 2870 and an engineer's design.
- Building surveyor: issues a Certificate of Likely Compliance before work starts. Our Form 35 goes with the application.
- Neighbours: underpinning or shoring a neighbour's property is protection work and needs a building surveyor.
- Landslip bands: low-risk work in a hazard band becomes notifiable, and Class 1 work in a High band becomes permit work. See landslip reports.
- Heritage: works to a place on the Tasmanian Heritage Register need Heritage Council approval. See heritage and older homes.
- Contracts: work of $20,000 or more falls under the Residential Building Work Contracts and Dispute Resolution Act 2016, with statutory warranties and claims within 6 years of practical completion.
More in our guide to low risk, notifiable and permit work in Tasmania.
How much does underpinning cost in Hobart?
Underpinning cost depends mostly on how many footings need support, how deep firm ground is, the method and site access. The contractor prices the building work; the engineering is a separate, fixed fee.
| Our engineering | Fee |
|---|---|
| Underpinning quote second opinion (documents and photos) | From $390 + GST |
| Crack and foundation report (site visit) | From $590 + GST |
| Underpinning design, stage inspections and certification | Fixed quote |
Prices exclude GST. Construction costs and what drives them: how much does underpinning cost in Hobart?
Related services
Before and alongside underpinning
Cracks & foundation movement report
Each crack measured and rated against AS 2870, the likely cause found and a clear repair priority, from an engineer with no repair to sell.
Learn more
Site classification & footings
Soil tests and AS 2870 site classification, then slab and footing designs that suit the ground, with a Form 35 for your building surveyor.
Learn more
Restumping & reblocking engineering
Subfloor inspection, stump and footing layout, documents for your building surveyor and certification for raised timber floors. Any licensed builder can do the work.
Learn more