Understanding how underpinning quotes work is the first step to comparing them fairly. Quotes that look very different in price might be quoting genuinely different scopes, or they might be making different assumptions about what is included and what will be added later. Knowing the standard line items, what a provisional sum means, and where contingency budgets should appear makes you a much more informed buyer of foundation repair services. For context on typical pricing ranges in Wagga, see our underpinning cost guide.
The standard line items you should see
A well-structured underpinning quote for a Wagga residential job should include most of the following items explicitly. If important items are missing, ask for clarification before accepting the quote.
| Line item | What it covers | Fixed or variable? |
|---|---|---|
| Mobilisation / site establishment | Getting the crew, tools and materials to site; traffic management if required | Usually a fixed lump sum |
| Engineering / geotech fees | Soil report, pin schedule, structural certification | Fixed, or referenced as a separate engagement |
| Underpinning pins (per pin) | Excavation, concrete, reinforcement, cure, grouting for each pin | Variable, depends on confirmed pin count |
| Access works | Fence removal, scaffold, temporary works to access work areas | Variable, site-specific |
| Spoil removal | Cartage and disposal of excavated material | Variable, driven by volume |
| Reinstatement | Paths, paving, garden beds, sub-floor areas, internal finishes disturbed by the work | Variable and often underquoted |
| Contingency / provisional sums | Allowance for conditions not visible before excavation | Should be explicitly stated |
A quote that shows a single lump sum without breaking into these components is harder to compare against other quotes and harder to manage if variations arise. Ask any contractor offering a lump sum to itemise the major components.
Per-pin pricing versus fixed-price contracts
Most underpinning quotes are structured in one of two ways.
Per-pin pricing means you pay a rate per underpin completed, with the total determined by the actual pin count. The engineering specification sets the design pin count, but the actual count can vary if site conditions are different from what was assumed during quoting. Per-pin pricing gives you transparency on the cost driver and means you pay for what was actually done, but it also means the final invoice can differ from the estimate.
Fixed-price contracts quote a total amount for the full scope as described. This gives budget certainty but typically includes a price premium to cover the contractor’s risk of unexpected conditions. Fixed-price contracts should still specify the scope precisely (how many pins, what depth, what reinstatement is included) so that you know what is covered.
Neither structure is inherently better. Fixed-price contracts suit homeowners who need cost certainty for financing or planning. Per-pin pricing suits situations where the scope is clearly defined and the risk of unexpected conditions is low. NSW Fair Trading, home building contracts outlines the requirements for written contracts in residential building work, including the requirement for a written contract on jobs above the statutory threshold.
For jobs over $20,000, a written contract is required under NSW home building law, and the contractor must be appropriately licensed. This is covered in more detail in our guide to how to choose a foundation repair contractor. If you’re managing the work yourself as an owner-builder, our guide to owner-builder underpinning in NSW covers what that role does and doesn’t allow on structural foundation work, and where a licensed underpinning contractor still needs to be engaged.
Engineering, geotech and inspection fees
A properly designed underpinning job requires professional input from at least one of the following, and often both.
Geotechnical report: A geotech engineer investigates the soil at the specific site, determines the soil classification and confirms the depth to stable bearing. This report is the basis for the pin design. Without it, the pin depth is a guess.
Structural engineering pin schedule: A structural engineer uses the geotech report to specify the number of pins, spacing, depth and construction specification. This document becomes the compliance record for the work.
These professional services are separate from the contractor’s labour and materials. They may be engaged directly by the homeowner, or the contractor may include them in the quote and engage them on the homeowner’s behalf. Understand which is the case before signing, because if something goes wrong it matters who engaged the engineer and what instructions were given.
Some contractors quote “based on our assessment” without an independent engineering specification. This is not necessarily wrong for a straightforward job, but it is a risk flag on a complex job. Ask what the pin design is based on and who has certified it.
For more on what a structural engineer’s report covers and costs, see how underpinning quotes vary, which covers the engineering scope question in detail.
Site establishment and access costs
Site establishment includes everything that has to happen before the first shovel of earth is turned. For a Wagga residential underpinning job, this typically includes:
- Attendance to the site and set-up of work area, tools and materials
- Traffic management or parking if street access is involved
- Temporary protection of neighbouring surfaces or garden areas
- Any temporary works needed to stabilise the structure during the repair sequence
Access costs relate to the specific constraints of getting to the work area. A job where all underpinning is along an easily accessible external wall has minimal access cost. A job that requires fence removal and reinstatement, temporary scaffolding to access a high external footing, or working in a confined sub-floor space at 450 mm clearance has access costs that can be significant.
A quote that does not itemise site establishment and access separately from the pin work itself may be including these silently in the per-pin rate, or may be planning to add them as a variation. Either way, ask directly: what is included in the per-pin price and what is not?
If a renovation or extension is also planned for around the same time, mention it when the quote is being scoped. Site establishment, scaffolding or fencing removal can sometimes be shared across both projects if they’re planned together rather than as two unrelated jobs. Our guide to sequencing renovations around foundation repair covers how to plan the order of works so you don’t pay to disturb newly finished surfaces a second time.
The concrete underpinning method explained guide covers the physical work sequence in detail, which helps understand what the labour component of a quote actually involves.
Contingency and variations: what triggers them
Variations are additions to the contract price that arise when the actual work reveals conditions different from those quoted. In underpinning work, the most common triggers are:
- Rock encountered at excavation: Not shown in the geotech report if the sampling was not directly below the affected footing section; rock excavation is slower and more costly than clay.
- Groundwater in the excavation: Requires pumping, may require temporary casing or other measures to allow concrete to be placed.
- Old services or obstructions under the footing: Unexpected pipes, original footings from a previous structure, or buried rubble can add time and cost.
- Additional pins required: If the engineer’s pin schedule is based on an inspection that did not fully capture the extent of movement, additional pins may be identified as excavation progresses.
- Footing in worse condition than assumed: If the existing footing material is found to be insufficient to support the underpinning bracket connection, remediation may be needed.
A reputable contractor will note these as contingency items in the quote, with an estimated allowance and a description of what triggers additional cost. If a quote has no contingency discussion at all, ask the contractor what happens if any of the above conditions are found.
Consider a contingency budget of around 10-20 percent of the quoted price as a sensible planning figure for a moderately complex job. For a staged approach that helps manage budget uncertainty, see staging foundation repairs when you cannot do it all at once.
Red flags in a quote
| Red flag | Why it matters |
|---|---|
| No engineering basis stated | Pin design may be a guess rather than a specification |
| Lump sum with no line-item breakdown | Cannot compare with other quotes; no transparency if variations arise |
| Very low per-pin rate with no scope detail | Scope may exclude significant items that will become variations |
| No mention of spoil removal or reinstatement | These costs may appear later |
| No contractor licence number | Licensed contractor required for residential building work in NSW |
| No specification of concrete strength or reinforcement | Work quality cannot be confirmed without this |
| No mention of certification or sign-off | Structural work should be certified by the responsible engineer |
| Very short quote document with no terms | Consumer protections are diminished without a properly formed written contract |
Our how to choose a foundation repair contractor guide covers the contractor selection side in detail. Council approval requirements, which sometimes apply to underpinning work, are covered in council approval for underpinning and restumping in Wagga and underpinning council approval in NSW. And if the paperwork in front of you now is a warranty document rather than a fresh quote, because movement has returned after an earlier underpinning job, our guide to foundation repair warranty claims covers how to build a case and what’s typically excluded.
For a foundation inspection before you get to the quoting stage, contact us to discuss what your site requires. Once you have a written quote in hand, our guide to underpinning finance options covers how homeowners typically fund the confirmed figure, whether that’s a mortgage redraw, a personal loan, or a staged payment arrangement with the contractor. A properly itemised quote should also give you a sense of the project’s likely disruption; see our guide to foundation repair while living in the house for what that typically means day to day.
FAQs
Should I get multiple quotes for underpinning?
Yes. Getting at least two, ideally three, quotes is strongly advisable for any underpinning job. This is not only about price: comparing quotes helps you understand what scope is standard, what is optional, and where contractors are making different assumptions. Make sure you are comparing the same scope before comparing prices. See why underpinning quotes vary so much for the full framework.
What is a provisional sum and how does it work?
A provisional sum (PS) is an estimated allowance for a cost item that cannot be fixed at the time of quoting, usually because it depends on conditions that will only be known during the work. The contract should specify what the PS covers, how variations are triggered and approved, and how the final amount is determined. PS items are not guaranteed to remain at the estimate; they can increase if the actual conditions require more than estimated.
Do I need a written contract for underpinning?
Yes, for work above the statutory threshold (currently $5,000 in NSW for most residential building work). NSW home building law requires a written contract specifying the work, price, terms, payments and other conditions. The contractor must also be appropriately licensed for the work and must hold the required insurance. Do not proceed with work above the threshold without a written contract.
What should reinstatement include?
Reinstatement covers making good the work areas after the structural work is complete. This typically includes backfilling and compacting excavation areas, reinstating concrete paths or paving that were removed for access, repairing or reinstating garden beds, and any internal finishes such as floors or walls that were removed to access the work. Get a clear list of what is included in reinstatement and what the contractor considers outside scope.
Is it worth paying for an independent engineer’s report before getting quotes?
Often yes, particularly for complex jobs or where the movement is significant. An independent engineer’s report gives you a specification that you can send to multiple contractors with confidence that they are all quoting the same scope. It also reduces the risk of being quoted on an undersized job that will need additional work later. The cost of the report is typically modest relative to the cost of the underpinning job. See our foundation inspections service for how this assessment works.
Related reading
- Underpinning cost guide
- How to choose a foundation repair contractor
- Underpinning service
- Foundation inspections service
- Council approval for underpinning in NSW
- Concrete underpinning method explained
- Staging foundation repairs: a budget plan
- Why underpinning quotes vary so much
- Council approval in Wagga Wagga
- Underpinning finance options