Guide 05 · Budget
Renovation Cost Estimator
A transparent budget built from your own numbers: material and labour rates, fixed extras and a contingency. No hidden price database — just clear arithmetic you can check.
Why this tool uses your prices, not ours
Material and labour costs change with region, season, specification and demand. A national "average price per square metre" can be wildly off for your street and your choice of finish. Rather than show figures we cannot stand behind, the estimator asks for rates from your own supplier quotes and tradesperson estimates. The structure is where the value lies: it makes sure nothing is forgotten.
What goes into a renovation budget
- Materials: the visible finishes plus the consumables — adhesive, grout, filler, primer, fixings, underlay and trims.
- Labour: quoted per square metre, per day or as a fixed price for the job.
- Preparation: stripping old finishes, levelling floors, making good plaster. This is often underestimated.
- Removal and disposal: skip hire or waste collection for old flooring, tiles and plasterboard.
- Tool and equipment hire: tile cutters, sanders, dehumidifiers or access towers.
- Professional fees and permissions: if structural, electrical or plumbing work is involved, check what approvals or certified trades your local regulations require.
- Contingency: money set aside for what you cannot see until work begins.
Getting quotes you can actually compare
Ask several tradespeople to price the same written specification: the room dimensions, the exact materials (or who supplies them), what preparation is included, and what happens to waste. Request an itemised quote that states whether tax is included, the expected start date and duration, and the payment schedule. Quotes that look cheap often exclude preparation or disposal. Written specifications remove that ambiguity.
Pricing models compared
| Model | Pros | Cons | Best for |
|---|---|---|---|
| Fixed price | Certainty of cost; the tradesperson carries the risk of slow progress | May include a margin for risk; changes to scope cost extra | Clearly defined jobs |
| Day rate | Flexible; you only pay for time used | Final cost is uncertain; needs trust and monitoring | Repairs and investigative work |
| Per m² or per unit | Easy to compare and to scale with room size | Preparation and awkward details may be charged separately | Flooring, tiling, plastering |
| Cost-plus | Transparent material costs | Little incentive to economise; requires record-keeping | Complex or evolving projects |
How much contingency?
A contingency of around 10–20% is commonly suggested for room renovations. Choose the higher end for older properties, when opening up walls or floors, or when the specification is not finalised. A newer home with a tightly defined, surface-level job can sit lower. Treat contingency as ring-fenced: if it is not needed, it is a saving at the end, not a budget for upgrades halfway through.
Where costs tend to creep
- Uneven subfloors that need levelling before new flooring.
- Blown or damp plaster discovered when paper comes off.
- Specification changes mid-project, especially to tiles or flooring.
- Extra fittings — new door thresholds, trimmed doors, replacement skirting.
- Delays that extend hire periods or day-rate labour.
DIY or hire a professional?
Doing it yourself
You save on labour, set your own schedule and gain a skill. Weigh that against slower progress, the chance of costly mistakes, tool purchase or hire, and a finish that may be less polished.
Hiring a tradesperson
You get speed, experience, a professional finish, and often a workmanship guarantee. The downsides are higher cost, the need to vet and schedule trades, and less direct control.
A hybrid approach often works well: handle the stripping, clearing and painting yourself, and hire professionals for skilled or regulated work such as tiling large areas, electrics and plumbing.