Most renovation budgets fail for the same reason: they are built as one hopeful number rather than a set of accounted costs. The work then arrives in a different order, at a different price, and the plan collapses quietly.
This guide sets out a simple structure you can build in an afternoon. It covers what to include, how much contingency is realistic, and how to stop small changes from turning into a second budget.
Key facts
- Labour is often 40 to 60 percent of a renovation bill.
- A contingency of 15 to 20 percent is normal for older homes.
- Provisional sums are estimates, not fixed prices.
- Every variation should be priced and approved in writing.
Contents
- Start with the total you can afford
- Split the budget into four buckets
- Price labour before materials
- Build a real contingency
- Track variations in writing
- When to pause and rebid
Start with the total you can afford
Decide the maximum you can spend before you look at finishes. Include savings you are willing to part with, not the maximum a lender might offer. Borrowing more because the kitchen looks better in a showroom is not a plan.
Then subtract a reserve you will not touch. If the total is too small for the work you want, cut scope rather than quality. A smaller project finished well is better than a large one abandoned halfway. Our value projects guide helps you choose what to keep.
Split the budget into four buckets
Use four buckets: construction, finishes, fees and contingency. Construction covers labour, structure and services. Finishes cover tiles, joinery, paint and appliances. Fees cover approvals, inspections and delivery. Contingency covers what nobody predicted.
Many homeowners put almost everything into finishes because that is the part they can see. In practice, construction and fees take the larger share. If the buckets do not balance, reduce the finish allowance first.
Price labour before materials
Get labour prices from at least three trades using the same written scope. Ask what is included, what is excluded and whether waste removal is part of the quote. A cheap labour price with more exclusions is often the expensive option.
Only after labour is priced should you shop for materials. Otherwise it is easy to spend the labour budget on a worktop and then discover the installation costs more than expected. Read our quote comparison guide before you sign anything.
Build a real contingency
Ten percent is a minimum for a straightforward newer home. Fifteen to twenty percent is more realistic for an older property, a bathroom, or anything that opens a wall. Hidden rot, old wiring and uneven floors are discovered during work, not before.
Keep the contingency in a separate account and treat it as spent. If the project finishes under budget, you have a bonus. If it does not, you are not borrowing at short notice or stopping work halfway through.
A budget is a decision made in advance, so the decision is not made by whoever is standing in front of you.
Track variations in writing
A variation is any change to the agreed scope, price or timeline. It should be described, priced and approved before the work happens. Verbal changes are the most common source of end-of-project disputes.
Keep every quote, invoice, variation and photo in one folder. When the final account arrives, you can check it against the agreed scope rather than relying on memory. This single habit prevents most budget surprises.
When to pause and rebid
If the quotes come back far above budget, do not simply choose the cheapest. Reduce the scope and re-tender the smaller job. Good trades price a clear, smaller project more accurately than a vague, ambitious one.
If a quote is dramatically lower than the others, find out why before celebrating. Missing items, uninsured labour or an unrealistic timeline usually explain the gap. A budget that holds is built on comparable numbers.
