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How Should I Tender a Renovation Project to London Builders?

For London renovations and extensions, tender to 3–4 builders on identical tender packages (architect's drawings + specification + room data sheets). Allow 3–4 weeks for builders to price. Compare like-for-like — flag missing items, vague allowances, unrealistically low prices. Engage a quantity surveyor (£900–£2,400) on projects over £150,000 for objective comparison. Expect 15–35% spread between cheapest and most expensive quote.

01

Tender package

Provide every builder the same documentation: architect's drawings (planning + building control), structural drawings, specification (NBS Lite or written), room data sheets (what each room contains), schedule of finishes (skirting, doors, flooring), kitchen drawing or PC sum, bathroom drawing + PC sum, electrical and plumbing schematic. Without identical packages, quotes are not comparable. PC (Prime Cost) sums for items not yet selected — agree allowance, balance up/down on actual selection.

02

Number of bids

3–4 bids is the sweet spot. Fewer than 3 = no benchmark. More than 5 = builders learn they're competing widely and prepare cursory quotes. Pre-qualify each builder before sending tender: company age (5+ years preferred), references on similar projects, insurance certificates, FMB or TrustMark membership, recent project photos.

03

Comparing quotes

Build a spreadsheet: row per scope item, column per builder. Look for: missing items (builder hasn't priced something), wide variances (which is the outlier?), PC sum allowances (are they comparable?), preliminaries % (10–18% normal; over 20% is high), profit and overhead (8–15% normal). Lowest price often signals missing items or contingency that will surface as variations. Best value usually mid-range with strong reference checks.

More questions

Related questions answered.

How long for builders to quote?

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3–4 weeks. Less and quotes are rushed; more and builders deprioritise.

Why is the cheapest quote risky?

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Either missing items (will surface as variations) or unrealistic margin (builder cashflows on next project). Always investigate why cheapest is cheap.

Should I share other builders' quotes?

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No — keep each tender confidential. Sharing prices invites collusion or undercutting that masks scope gaps.

Does Builderr tender to RIBA-format packages?

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Yes — we price NBS Lite tender packages, return quotes within 3 weeks with itemised schedule, fully comparable to other London builders.

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