Every buyer underestimates the refurbishment. Not by a little. The usual pattern is a number arrived at from listing photos, no contingency, and a discovery in week three that the house needs rewiring.
The figures below are planning allowances for a typical three bedroom terrace or semi of around 850 to 950 square feet in the North West, using competent local trades rather than a main contractor. Use them to work out whether a deal is worth pursuing. Then price the actual job from three quotes before you exchange.
The structural and service items
These are the ones that decide whether a project is viable, and none of them show up in a photograph.
Item Planning allowance Full rewire, including consumer unit £4,000 to £6,500 New boiler and full heating system £3,500 to £5,500 Roof recovering, terrace or semi £6,000 to £12,000 Damp proof course and replastering to affected walls £2,500 to £5,000 Windows and external doors, uPVC throughout £4,500 to £8,000 Replastering throughout £3,500 to £6,000
If two or more of those are needed, you are in a full refurbishment whatever the agent's description says.
The rooms Item Planning allowance Kitchen, supplied and fitted, mid range £5,000 to £9,000 Bathroom, supplied and fitted £3,500 to £5,500 Flooring throughout £2,000 to £4,000 Decoration throughout £2,500 to £4,500 Doors, skirting, architrave and ironmongery £1,500 to £3,000 Garden clearance and basic landscaping £1,000 to £3,000 The costs people forget
Waste. Skips, hire and tip runs on a full strip out run to £800 to £2,000. Clearing a hoarded house can be more than that on its own.
Scaffolding. Any roof or upper elevation work needs it. Allow £1,000 to £2,500 depending on duration.
Building control and professional fees. Notifiable work needs sign off. Structural changes need a structural engineer's calculations. Allow £500 to £2,000.
Utilities and council tax while you own it. Six months of standing charges and council tax on an empty property. Some councils charge a premium on long term empties rather than a discount, so check the local policy rather than assuming.
Contingency. 10% on a cosmetic refresh, 15% on a full refurbishment, and take it seriously. It is not padding, it is the drain run you did not know about.
Three rough totals
Cosmetic refresh. Kitchen, bathroom, flooring, decoration and a tidy garden, with services already sound. £14,000 to £22,000.
Full refurbishment. Rewire, heating, plaster, windows, kitchen, bathroom and finishes throughout. £32,000 to £48,000.
Full refurbishment with a roof and structural work. Add £10,000 to £20,000 on top of that.
Extensions and loft conversions sit outside this entirely and should be costed separately per square metre, with a design and a planning position before you count the value they add.
Why the number matters more than it looks
Refurbishment does not just come off your profit. It comes off what you can pay for the house. If your budget is out by £8,000, your maximum purchase price was out by £8,000, and you have either overpaid or lost the deal to someone whose sums were better.
That is the whole argument for doing the calculation properly before you offer. Bricks 'N' Mortar takes an end value from comparable sales and works backwards through refurbishment, fees, stamp duty and finance to a maximum purchase price, with every assumption editable so you can put your own quotes in place of ours.
These are illustrative planning ranges for the North West in 2026, not quotations. Costs vary significantly by region, specification and the condition of the individual property.