How to Estimate a Renovation
Estimating a renovation well means pricing what you can see, clearly flagging what you can’t, and building in a sensible contingency for the gap between the two. Break the job into trade sections, price demolition and make-good on their own line, allow a contingency sized to how much of the existing structure has been inspected, and use provisional sums for anything that can’t be confirmed until the job is opened up. That’s what gets a renovation quote to hold up once work actually starts.
Key takeaways
- Renovations carry more pricing risk than new builds because much of the job — existing structure, services and finishes — is hidden until work starts.
- Break the renovation into trade sections — demolition, structural, electrical, plumbing, wet areas, finishes — so each scope and its assumptions are visible and checkable.
- Price demolition, waste removal and make-good as their own line items rather than folding them into a vague allowance.
- Add a sensible contingency sum sized to how much of the existing structure has been inspected, state your assumptions and exclusions clearly, and use provisional sums for genuine unknowns.
- Protect your margin on fixed-price renovation work with a written variations process — never absorb the cost of a latent condition into the original price.
Why renovations are riskier to price than new builds
Renovation work is harder to price accurately than a new build because a large part of the job is hidden until walls, floors or ceilings are opened up — and a fixed price agreed before that discovery is really a bet on what you can’t yet see.
On a new build, the site starts as a slab or a frame, and quantities can be measured straight off the plans. On a renovation, the existing structure, services and finishes sit underneath and behind everything you’re pricing, and no set of plans can fully show their condition. That gap between what’s documented and what’s actually there is where renovation quotes come unstuck.
- Unknowns behind linings and structure that only become visible once the job is opened up
- Latent conditions — rot, movement, damp, or non-compliant existing work
- Demolition and make-good to a standard that never appears on the drawings
- Matching existing finishes, tiles, timber or paint that may no longer be available
- Working around occupants living in, or operating from, the property during the works
Break the job into trade sections before you price anything
The most reliable way to estimate a renovation is to break it into trade sections and price each one separately, the same way a Bill of Quantities is built for a new build. That turns one intimidating lump-sum guess into a series of smaller, checkable estimates.
Working trade by trade also makes your assumptions visible. If the electrical section assumes the existing switchboard is compliant and doesn’t need upgrading, that assumption sits next to the electrical price — not buried inside a total figure nobody can question.
- Demolition and strip-out
- Structural and carpentry — framing, bearers, joists, doors and windows
- Electrical
- Plumbing and drainage
- Wet areas — waterproofing, tiling, fixtures
- Finishes — plastering, painting, flooring, cabinetry
- Preliminaries and site costs
Price demolition and make-good as their own line items
Demolition, waste removal and make-good are some of the most commonly underpriced items on a renovation, because they get folded into a vague allowance instead of being scoped properly. They deserve their own line items, since the volume of waste and the amount of make-good required is rarely obvious from a floor plan.
Make-good is especially easy to under-scope: patching a wall after removing an old vanity, matching cornice after a wall comes out, or reinstating flooring where a partition used to sit. None of it looks dramatic on its own, but across a whole renovation it adds up — and it’s far easier to price up front than to argue about once the strip-out is done.
- Strip-out labour and disposal, including skip bins and any waste levies
- Temporary works — propping, dust screens, temporary power or water
- Patching and making good adjoining surfaces disturbed by removal work
- Any hazardous-material handling identified before work starts
Allow a sensible contingency and be clear about your assumptions
Because a renovation always carries some risk that can’t be inspected away, every renovation quote should include a contingency sum — and how big it needs to be depends on how much of the existing structure has actually been opened up and checked before you price it. A property with a pre-purchase inspection and some opened wall sections warrants a lower contingency than one priced from photos and a walk-through.
Just as important as the contingency figure is stating your assumptions and exclusions in writing, on the quote itself — what you’ve assumed about existing wiring, structure and compliance, and what’s specifically excluded. That’s what separates a fixed price that holds up from one that turns into a dispute.
Renovation risk and contingency checklist
Before locking in a fixed price, check: has anyone opened up walls, ceilings, subfloor or roof space to inspect condition; are there signs of past water damage, rot or pest activity; is the existing wiring, plumbing or structure likely to be non-compliant with current standards; can materials to match existing finishes still be sourced; will the property be occupied during the works; and have you listed your assumptions, exclusions and contingency sum clearly on the quote.
Use staged pricing and provisional sums for genuine unknowns
Not everything on a renovation can be priced firm, and pretending otherwise is how quotes fall apart mid-job. Where a cost genuinely can’t be confirmed until work starts — subfloor condition once the old flooring is lifted, or wall framing once the linings come off — price it as a provisional sum rather than guessing at a firm figure.
Staged pricing works alongside provisional sums: price the visible, confirmable scope firm, and set out a clear process for confirming provisional items once they’re exposed, before work on that section proceeds. That keeps the client informed at each stage, and protects you from carrying a cost nobody could have priced accurately in the first place.
Protect your margin on fixed-price renovation work
A fixed price only protects your margin if variations are managed properly from day one. Any scope that falls outside your stated assumptions and exclusions — a latent condition, a client-requested change, an item that was never in the original quote — should go through a written variation before the work proceeds, with the cost and any time impact agreed up front.
The biggest margin killer on renovation work is treating a latent condition as if it were your error to absorb. If it was excluded, or couldn’t reasonably have been known before the job was opened up, it’s a variation, not a correction. Tracking actual costs against your original trade-by-trade estimate as the job progresses also flags early if a section is running over, while there’s still time to manage it.
How My Trade Hub speeds up renovation estimating
My Trade Hub is built to make trade-by-trade renovation estimating faster, without cutting corners on detail. Upload the plans and My Trade Hub’s automated takeoff measures the items on them, so you’re not scaling a PDF by hand for every section of the job.
From there, your own editable rates library — labour, material and plant rates you control — applies to the measured quantities, and every rate stays adjustable if a quantity or a rate needs correcting. My Trade Hub then builds this into a Bill of Quantities and a clear tender document, with your assumptions and exclusions stated up front, so the client can see exactly what is, and isn’t, included. Preparing a priced tender this way is 60–75% faster than building it up manually.
It’s free to create a My Trade Hub account, and tiered plans in AUD cover the estimating and tender preparation itself, with no lock-in contracts.
- Automated takeoff measures items straight from your uploaded plans
- Editable rates library applies your own labour, material and plant rates automatically
- Bill of Quantities generated trade by trade, so nothing gets buried in a lump sum
- A clear tender document with stated assumptions and exclusions
- A priced tender ready 60–75% faster than pricing the same job manually
A worked example: pricing a renovation trade by trade
The table below shows how a renovation estimate comes together once it’s broken into trade sections, following the same approach set out above. The figures are illustrative only — every real renovation should be priced from your own current rates library, against the actual scope and condition of that job.
| Trade section | Example scope | Typical unit | Example subtotal |
|---|---|---|---|
| Demolition & strip-out | Strip existing fit-out and dispose of waste | m² floor + wall | Illustrative example |
| Structural & carpentry | Minor reframing, new openings, bearers | linear metre / item | Illustrative example |
| Electrical | Rewire affected areas, new circuits, fittings | per point | Illustrative example |
| Plumbing & drainage | Relocate fixtures, new drainage runs | per fixture | Illustrative example |
| Wet areas | Waterproofing and tiling | m² | Illustrative example |
| Finishes | Plastering, painting, flooring, cabinetry | m² / linear metre | Illustrative example |
| Contingency | Allowance for latent conditions | % of trade sections | Illustrative example |
| Preliminaries & margin | Site costs and profit | % of subtotal | Illustrative example |
Frequently asked questions
How do you estimate the cost of a renovation?
You estimate a renovation by breaking the job into trade sections — demolition, structural, electrical, plumbing, wet areas and finishes — pricing each against your own rates library, then adding a contingency sized to how much of the existing structure has actually been inspected, and flagging anything you can’t confirm as a provisional sum.
What should be included in a renovation quote?
A renovation quote should include a trade-by-trade breakdown, a demolition and make-good allowance, a stated contingency sum, provisional sums for genuine unknowns, and a clear list of assumptions and exclusions, so the client knows exactly what the price does and doesn’t cover.
How much contingency should I add to a renovation quote?
There’s no single figure that suits every job — it depends on how much of the existing structure has actually been opened up and checked before you price it. A property with limited pre-inspection generally warrants a higher contingency than one where walls, subfloor or roof space have already been examined.
What is a provisional sum in a renovation quote?
A provisional sum is an amount included in a quote for work that can’t be priced firm because its true scope isn’t known until the job is opened up — subfloor repairs that can only be assessed once old flooring is lifted, for example — and it’s confirmed, up or down, once the item is exposed.
How do you price demolition and make-good in a renovation?
Price demolition and make-good as their own line items rather than folding them into a general allowance — covering strip-out labour, disposal and any waste levies, plus the make-good needed to adjoining surfaces once the old fit-out is removed.
Why are renovations harder to quote than new builds?
Renovations aren’t necessarily more expensive to quote, but they are harder to quote accurately, because much of the job — existing structure, services and finishes — is hidden until work starts, unlike a new build where quantities can be measured straight off the plans.
How can I protect my margin on a fixed-price renovation?
Put a written variations process in place before work starts, treat any latent condition or out-of-scope request as a variation rather than absorbing the cost, and track actual costs against your original trade-by-trade estimate as the job progresses, so you can catch overruns early.
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