Fixing up an older home could cost £170,000, industry data suggests

Bringing an older three-bedroom semi-detached house up to the energy efficiency, comfort and technology of a new-build home could cost around £170,000, according to The Intermediary, reporting research from the Home Builders Federation (HBF).

The figure is well above what buyers expect to pay. The same research found 56% of adults expected to spend no more than £50,000 on a fixer-upper, and 29% expected to spend £25,000 or less. The HBF also found that almost all new-build homes achieve an EPC rating of A or B, compared with fewer than 5% of older homes, and that new homes use around 30% less energy on average.

Work carried out with Octopus Energy put the running-cost gap in cash terms too: an average new-build household saves around £420 a year on energy bills compared with an older, EPC D-rated home, rising to around £650 a year against an EPC F- or G-rated property. Separately, 42% of respondents said mortgage affordability limits could push them towards buying a property that needs significant renovation, whether they'd planned for that or not.

HBF executive director Steve Turner put it simply: the "added value of the technology and modern features built into today's new homes is easily overlooked."

Where the £170,000 actually goes

The HBF's figure is a whole-house estimate covering everything from insulation to heating to wiring to layout changes — most buyers doing up an older home won't take on all of it at once. It's worth breaking down what the big-ticket items look like using current UK costs, so you can see which upgrades deliver the most for the money.

Heating. Swapping an old gas boiler for a modern one typically costs £2,200 – £3,650, with a full like-for-like New boiler costing around £2,800. Many older homes upgrading toward new-build energy performance now go further and fit a heat pump instead: a typical Air source heat pump costs £12,900, though this can be reduced by £7,500 under the Boiler Upgrade Scheme in England and Wales (or a Home Energy Scotland grant of up to £7,500, plus an optional interest-free loan, in Scotland) provided the installer is MCS certified. Heat pumps and other energy-saving materials also qualify for 0% VAT until 31 March 2027, which is a meaningful saving on a project this size.

Insulation. External wall insulation is one of the biggest single differences between an old home and a new one for comfort and running costs. A typical External wall insulation project runs to £20,300 – £33,800, and like heat pumps it currently qualifies for 0% VAT.

Windows. Older homes rarely match new-build glazing standards. Replacement windows for a typical house costs around £3,600, and any installer doing the work needs to self-certify compliance with building regulations (typically through FENSA or CERTASS).

Electrics. Older wiring often needs bringing up to modern standards before other work can proceed safely. A full House rewire typically costs £6,800, and a new consumer unit is notifiable work that must be done by a registered electrician or notified to building control.

Solar and storage. New-build homes increasingly come with solar as standard. Retrofitting Solar panels to an older roof costs around £12,500, also 0% rated for VAT until March 2027.

Add these together and it's easy to see how a whole-house energy and comfort upgrade reaches six figures — particularly once labour, scaffolding, redecoration and knock-on costs (replastering after rewiring, for instance) are factored in. The HBF's £170,000 figure also likely includes layout and space changes that go beyond energy performance, which this list doesn't cover.

What this means if you're buying an older home

The gap between what buyers expect to spend (£25,000–£50,000) and what a full new-build-equivalent upgrade can cost is large enough that it's worth pricing out your own priorities before making an offer on a property that needs work. You don't have to do everything the HBF costed — most homeowners tackle heating, insulation or windows one at a time, and the Warm Homes Plan, published in January 2026, is due to phase in further grants and low- or zero-interest loans for these kinds of upgrades over the next few years.

If you already have a quote in hand for any of this work, it's worth checking it against typical local costs using the "is my quote fair" tool before signing anything — our figures are calculated from labour hours multiplied by local rates plus materials, checked against market prices and real quotes, so you can see whether a quote sits in the normal range for your area.