Is Your Builder's Quote Fair?

Rough 2026 London numbers: kitchen extensions land around £2,200/sqm, side returns around £2,300/sqm, loft conversions around £1,800/sqm, bathrooms around £1,500/sqm, full property renovations around £1,400/sqm, garage conversions around £1,300/sqm. Anything within 15% either side of those is fair. More than 30% off in either direction and I'd want to understand why. Too cheap usually means something important is missing from the scope or the builder is underquoting to win the job and will chase variations later. Too expensive means either premium spec or a builder who's padding. Ask for a line-by-line breakdown before you sign.

Industry standard for a solid London builder is 10 to 15% on signature, with the rest released in stage payments tied to completed work. Up to 20% I'll accept if there's a big specialist item on order (custom steelwork, imported stone). Above 25% is a red flag. Above 40% and I'd walk away. If a builder wants half the money up front, they're either badly cashflowed or they're planning to disappear with it. Good builders have working capital. They don't need your money to buy materials for the first week. Pay deposits against a written contract and keep receipts for everything.

Print the result. Walk through it with the builder. 'Your total's fair but the VAT treatment is unclear — can you confirm it's included in writing?' 'You haven't listed Building Control. Is that on top?' 'Your deposit's 30%, I'm paying 15% and we'll schedule the rest against milestones.' Most reasonable builders will adjust. The ones who react badly to specific, polite questions are telling you something. You're not trying to knock them down on price. You're making sure you both understand what's in the job and what isn't. The best outcome is a clearer quote you can actually compare against others. If you want me to look at the quote myself, send it over.