How accurate is a RICS cost plan?

Stage 2 ±15–20%; Stage 3 ±8–12%; Stage 4 ±3–5%. Inaccuracy sources: design changes during build, unforeseen ground conditions, late planning conditions, market price changes during long programmes. Good cost plans include explicit risk allowances. Update when scope changes; compare to BCIS published benchmarks for sanity.

Can my architect produce one?

Architects produce indicative cost estimates but not RICS-compliant cost plans. Architects rely on £/m² rate-based estimates that miss project-specific complexity. For accurate cost planning engage MRICS Chartered Quantity Surveyor in addition to architect. Many London practices have associated QS partners; some larger practices have in-house QS — verify MRICS qualifications.

Initial concept cost plan RIBA Stage 2: 2–4 weeks. Detailed cost plan Stage 4: 4–8 weeks. Updates between stages: 1–2 weeks. Monthly cost reporting during construction. Total QS engagement typically 6–14 months for 12-month construction. Plan QS alongside architect from Stage 1 — proactive cost planning more valuable than reactive checking.

How does it differ from builder's quote?

Builder quote is net price for defined contract scope at builder's interpretation. Cost plan is gross project cost including professional fees, VAT, FFE, contingency, allowances. Cost plan ~30–50% higher than builder net quote; represents true budget required. Compare cost plans across contractors; compare builder quotes only against cost plan or specification.

RICS Cost Plan London Renovation 2026 | Builderr

What Is a RICS Cost Plan for London Renovation?

A RICS cost plan is a detailed pre-tender budget prepared by a Chartered Quantity Surveyor (MRICS) breaking down each work package with explicit allowances for contingency, prelims and risk. Fee £1,500–£8,500. Essential for renovations over £250,000, listed buildings, basement conversions, and lender-financed projects. Updated through RIBA stages from ±20% (concept) to ±5% (technical design). Typically recovers 5–15× fee in scope discipline.

What an RICS cost plan covers

Formal cost plan produced under NRM 1 (RICS New Rules of Measurement: Order of Cost Estimating and Cost Planning). Structure: substructure (foundations, underpinning, basement); superstructure (frame, floors, roof, external/internal walls, windows, doors); internal finishes (wall, floor, ceiling); fittings/furnishings/equipment (kitchens, joinery, sanitary ware); services (mechanical, electrical, comms); external works (landscape, drainage); preliminaries (site setup, programme, supervision); contingency (design risk, construction risk, exceptional risk); professional fees; VAT and statutory charges. Each line shows quantity, rate, total and assumption notes. Accuracy improves with RIBA stage: Stage 2 ±15–20%; Stage 3 ±8–12%; Stage 4 ±3–5%.

Why use a Chartered QS

Without cost plan: renovations tendered against drawings only, contractors price interpretation, scope creep adds 18–35% to final spend. With cost plan: scope measured before tender; contractors price identical scope; client knows true budget. Fee 0.8–2.5% of construction cost for residential renovation; flat £1,500–£3,800 for smaller projects; £4,500–£18,000 for large/complex. ROI: typically saves 5–15% of final spend through competitive tender and scope discipline. Essential for: projects >£250k, listed buildings, basements, lender funding, multiple-trade coordination. RICS Find a Surveyor (ricsfirms.com) lists qualified firms. Verify MRICS or FRICS designation; residential renovation specialism; 5+ years London experience.

Cost plan vs builder's quote

Common confusion. Builder's quote: priced against drawings, may exclude items, includes builder margin, no independent measurement, no contingency. Typical builder quote omissions: VAT, decorating, sanitary ware, flooring, landscaping, planning fees, insurance, finance costs, contingency. Cost plan: independently measured, includes all packages, explicit contingencies (5–15% design, 5–10% construction), professional fees, VAT, gross cost. Gross cost in cost plan is 25–55% higher than net build cost in builder quote — but represents actual cash required to complete. Renovations consistently overrun because client compared only builder's net quote without adding professional fees, FFE, VAT and contingency. Cost plan exposes true cost upfront.

When you need one

Critical: (1) Projects over £250k. (2) Listed buildings or conservation — heritage cost uncertainty. (3) Basement conversions — high cost, high risk, structural complexity. (4) Lender-funded — BCIS cost plan often required by lender or development finance. (5) Properties bought to renovate — informs purchase price and viability. (6) Tendering multiple contractors. (7) Insurance reinstatement valuations — RICS format required. Less essential for: renovations under £100k, single-trade work, design-and-build packages with fixed prices. For £100–250k decision depends on complexity and risk appetite.