How much value does a loft conversion add?
A loft conversion adding a bedroom and bathroom typically increases a home's value by 10 to 20 percent. The uplift is largest where it takes the house from three bedrooms to four, because that moves it into a different bracket for buyers rather than simply adding floor space.
The bedroom count matters more than the square metres. Buyers search by number of bedrooms, so a conversion taking a house from three to four often produces a step change in the pool of interested buyers and therefore in price. Adding a fifth bedroom to a four-bedroom house adds space but rarely produces the same jump.
Adding an en-suite alongside the bedroom materially improves the return, and in a Fulham terrace it often converts the loft into a principal suite — which is a different proposition to a fourth child's bedroom. It is generally worth the extra £8,000 to £12,000 the bathroom adds to the build cost.
Two cautions. The uplift is capped by the ceiling price for the street: no amount of added space makes a house worth more than the best house on the road. And the conversion must be properly certificated — an unauthorised loft room adds nothing at valuation and can reduce the price, because the buyer's solicitor will raise it and the buyer will price in the risk.
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