Why this is where most BMV deals actually die
The valuation gap is usually the easy part to check. Refurbishment cost is where optimistic investors lose money, because it's tempting to eyeball a property and estimate low. A genuine below-market-value deal on paper regularly turns into a break-even project once real trade quotes come in.
What "needs modernising" actually costs
A full kitchen replacement typically runs several thousand pounds even at a modest specification; a bathroom similarly. Rewiring a full property, replacing a boiler and heating system, and damp treatment can each run into five figures depending on severity. None of these are optional once identified — they're required to make the property lettable or mortgageable, not cosmetic upgrades you can defer.
Always add a genuine contingency
Budget at least 10–15% on top of your best trade estimate for a refurbishment project, not as a formality but because unexpected issues — hidden damp behind old plaster, a roof that needs more than a patch, wiring that fails inspection — are the norm on older or long-neglected properties, not the exception.
A worked example
Comparable sold value: £300,000. Asking price: £250,000 — a headline £50,000 "discount." Kitchen and bathroom: £18,000. Rewiring: £9,000. Damp treatment: £6,000. Contingency at 12%: £4,000. Finance and holding costs during the works: £5,000. Real discount after costs: roughly £8,000 — genuinely BMV, but a fraction of the headline figure, and only worthwhile if the numbers still work at that smaller margin.
Get real quotes before you commit, not after
A trade walkthrough before exchange is worth the time it costs. An auction lot in particular won't wait for you to discover the true refurbishment cost after completion — by then you've already bought it.