How much should I budget for vetting and contract review?

Vetting time: 8-15 hours of client time over 3-5 weeks to assess 3 quotes properly (reading quotes, visiting references, checking insurance, comparing line items). Contract review by a solicitor on projects above £100,000: £400-£900 typically, sometimes included in your conveyancing solicitor's retainer. Independent quantity surveyor or building surveyor pre-contract review: £800-£2,500 on projects above £200,000 and routinely identifies £4,000-£15,000 in line-item issues. These are upfront costs but reliably positive ROI on any project above £50,000.

Should I use a contractor or a design-and-build firm?

Both models work; choose based on project complexity. Traditional procurement (architect designs, contractor builds) suits projects above £150,000 where design quality is the priority and you can manage the architect-contractor relationship; cost certainty is lower because variations during build are common. Design-and-build firms (architect and contractor under one roof) suit projects £50,000-£300,000 where execution speed and cost certainty matter more than bespoke design; you trade some design flexibility for streamlined accountability and tighter pricing. Builderr operates the design-and-build model with architect-led design integration as standard.

What questions should I ask a London builder?

Ten questions reveal most of what you need: (1) How many years has the company been trading and how many directors? (2) Can I see your PL and EL insurance certificates today? (3) Which trade bodies are you a member of? (4) Can you provide three completed addresses in this borough from the last 12 months? (5) Who is your structural engineer and can I have their PI insurance details? (6) What contract will we use? (7) What payment schedule do you require? (8) What warranty do you provide and is it insurance-backed? (9) How do you handle variations? (10) Who is the named project manager and how often will we meet?

What if something goes wrong mid-build?

First, raise the issue in writing immediately — document, photograph, email. Second, refer to the contract dispute resolution clause: most JCT and FMB contracts require mediation before adjudication, and adjudication before court. Third, contact the trade body (FMB, TrustMark, NHBC) — most have free or low-cost dispute resolution services available to members and their clients. Fourth, withhold further payment beyond the disputed milestone until resolution. Fifth, take legal advice — a London construction solicitor costs £250-£450 per hour and a 1-2 hour consultation usually clarifies the position. Never accept verbal promises to fix things later; always insist on written remediation plans with dates.

How to Find a Trusted London Builder 2026 | Builderr

How Do I Find a Trusted Builder in London?

Find a trusted London builder by filtering candidates through five gates: company registration (3+ years at Companies House), trade body membership (FMB, NHBC, TrustMark, Chartered Building Company), valid insurance (PL £5m+, EL £10m+), three completed references in the last 12 months that you visit in person, and a JCT or FMB fixed-price contract with industry-standard payment milestones.

Where to source candidate builders

The London builder market has approximately 25,000 registered companies offering domestic construction work, of which 3-5% pass standard professional vetting. Effective sourcing channels: FMB Find a Builder (Federation of Master Builders membership requires 3+ years trading, inspection, references, financial check); TrustMark Government-Endorsed Quality Scheme (independent quality assurance backed by insurance); Chartered Building Company / Chartered Building Consultancy via the CIOB; NHBC Approved Builder for warranty-backed work; architect or surveyor recommendation tied to their own professional reputation. Less effective and best avoided as sole source: Checkatrade, MyBuilder and Rated People (low entry barrier, sponsored placements, review manipulation); leaflet drops; Facebook local groups; door-knockers and 'we have leftover materials' approaches. Combine 2-3 channels for shortlist of 5-8, then apply vetting filter to land 3 for quote.

The vetting checklist

Apply the same six gates that Builderr uses for subcontractor vetting. Companies House check: limited company with 3+ years filed accounts, no recent change of company name or director, no County Court Judgments against the company in 2 years. Insurance check: request current Public Liability certificate £5m minimum and Employers Liability £10m minimum, verify with the insurer's policy number. Trade body check: confirm active membership of FMB, TrustMark, NHBC or Chartered Building Company by ringing the body, not just trusting a website logo. References: three completed projects in the last 12 months, similar in scope and budget, addresses provided, visit at least one in person, speak to the client by phone (not email), ask about variations, communication and final cost vs quote. Reviews: search Google, Trustpilot and Houzz independently, look for consistent feedback over 12+ months not a cluster of reviews in 30 days. Quote structure: fully itemised, fixed-price, no provisional sums on definable items, payment schedule tied to milestones, no upfront above 10%.

Red flags that signal a cowboy

Eight red flags reliably identify problem contractors. Quote materially below the market range (more than 15% under three other quotes) — almost always indicates missing items that will return as variations. Pressure to sign quickly or claim a 'discount expires this week' — legitimate contractors do not use sales tactics. Demand for more than 10% upfront deposit, or large material payments before works — cashflow risk on their end. Reluctance to provide insurance certificates, trade body proof or written contract — disqualifies the contractor. Vague references, no completed addresses or addresses outside London — likely fake. Trading from a residential address with no commercial premises and no office staff. No structural engineer named on the quote. Pressure to skip party wall notices, planning or building control to 'save time and money' — exposes you to legal and financial liability that the contractor will not share. Any one of these red flags justifies removing the contractor from consideration; two or more is decisive.

Contract structure for protection

Use a recognised standard contract, not a one-page quote. For projects under £100,000, the FMB Domestic Building Contract is straightforward and free for clients. For projects £100,000-£500,000, the JCT Minor Works or JCT Home Owner Contract provides robust dispute resolution and is widely understood. For projects above £500,000, JCT Intermediate Building Contract with named subcontractors and full design responsibility allocation. Key clauses to confirm: liquidated damages for late completion (typically £150-£500 per day); retention of 5% pending defects walk at 6 months; defects liability period of 12 months minimum; variation order procedure requiring written instructions; mediation and adjudication clauses before litigation; insurance obligations on both parties. Always have a solicitor review the contract for projects above £100,000; legal review costs £400-£900 and routinely saves multiples of that in averted dispute.