How I Found a Builder I Could Actually Trust
I interviewed 8 builders for my extension. Three ghosted me after quoting. Two couldn't explain their payment schedule. One wanted 60% upfront. Another said "don't worry about contracts, we're mates now." I learned the hard way that choosing a builder isn't about finding the cheapest quote—it's about finding someone you can trust with £80,000 and six months of your life.
Here's what I wish someone had told me before I started. Not theory from a magazine—actual experience from someone who made mistakes so you don't have to.
The 5 Non-Negotiables (I Learned This the Hard Way)
I nearly hired a builder who seemed perfect—great references, good quote, friendly guy. Then I asked for his insurance certificate. He said he'd email it. A week later, still nothing. I pushed. Turns out he wasn't insured at all. If something had gone wrong, I'd have been liable. Here are the five things I now check before I even look at a quote:
1. Public Liability Insurance (Minimum £2 Million)
My Rule
If they can't email me proof of insurance within 24 hours, they don't have it. No exceptions. I ask for the actual certificate showing policy number, coverage, and expiry date. "It's being renewed" means "I don't have it."
What you need to see:
- Policy number and coverage amount
- Current expiry date (must cover your build period)
- Insurer name (check they're legitimate)
If they hesitate or say "it's being renewed," walk away. No exceptions.
2. Companies House Registration
Search their company name at companies house.gov.uk. What you're looking for:
- Active status (not dissolved or in liquidation)
- Directors' history – have they dissolved multiple companies with debts?
- Financial accounts – are they trading solvent?
- Time in business – at least 3 years is preferable
What I Discovered
One builder I was considering had run 3 companies in 5 years—all dissolved with debts. That's not bad luck, that's a pattern. I found this in 10 minutes on Companies House. It saved me from a disaster.
3. Trade Association Membership
Look for membership in recognized bodies:
- Federation of Master Builders (FMB) – stringent vetting, independent arbitration
- Checkatrade – verified reviews, must pass checks
- TrustMark – government-endorsed quality scheme
- Local Authority Building Control – registered competent person schemes
Membership doesn't guarantee perfection, but it shows commitment to standards and provides recourse if things go wrong.
4. References from Recent Projects
Not just "happy customers"—specifically similar projects to yours. Ask for:
- At least 3 references from the last 12 months
- Projects of comparable size and complexity
- Contact details you can actually verify
Then actually call them. Don't just read written testimonials.
5. Written Quotation with Detailed Breakdown
My Biggest Mistake
I accepted a quote that just said "£65k for extension." No breakdown, no milestones. When the builder asked for more money halfway through, I had no way to prove what was included. Now I only work with builders who break down every single cost. If they won't, they're hiding something.
A proper quote must include:
- Itemized costs for materials and labour
- Payment schedule (never pay everything upfront)
- Start and completion dates with provisions for delays
- Scope of work broken down by phase
- Exclusions clearly stated
- How variations will be priced
A one-page quote with a single total figure is useless for comparison and protection.
The Questions That Revealed Everything
I used to just listen to builders tell me how great they were. Now I ask specific questions and watch their reactions. The good ones answer confidently. The rest get defensive or vague.
The One Question That Matters Most
"Can I visit one of your current sites and speak to that homeowner?" Good builders say yes immediately. Bad builders make excuses. This one question saved me from hiring two builders who talked a good game but had zero active projects.
About Their Experience
- "How many extensions like mine have you completed in the last 2 years?"
- "Who will be managing my project day-to-day?"
- "What's your typical team size and how many projects do you run simultaneously?"
- "Can I visit a current site to see how you work?"
About the Build Process
- "How do you handle communication—daily updates, weekly meetings?"
- "What happens if I'm not happy with something?"
- "Who's responsible for ordering materials and managing deliveries?"
- "How do you handle variations and additional costs?"
- "Will you use subcontractors? If so, for which trades?"
About Payments and Protection
- "What's your payment schedule and why is it structured that way?"
- "Do you offer a warranty? If so, what does it cover and for how long?"
- "What happens if you can't complete the work?"
- "Do you have professional indemnity insurance?"
Red Flags That Made Me Walk Away
I've walked out of meetings with builders who seemed perfect on paper. Here's what made me leave:
The Cash Discount That Wasn't
One builder offered me "15% off for cash." Sounds great, right? Wrong. That's tax evasion, and it means zero paper trail if things go wrong. I said no. He got aggressive. That told me everything I needed to know.
- Asking for large upfront payments – more than 10-15% before work starts is suspicious
- Cash-only or "discount for cash" – suggests tax avoidance and leaves you unprotected
- No written contract or vague terms – oral agreements are worthless when disputes arise
- Pressure to sign immediately – legitimate builders don't use high-pressure sales tactics
- Can't provide proof of insurance or registration – either uninsured or hiding something
- Unwilling to put things in writing – "trust me" isn't a contract
- No fixed address or uses only mobile contact – how will you reach them when problems emerge?
Trust Your Gut
One builder's quote was £8k cheaper than everyone else's. I should have been happy. Instead, I felt uneasy. Turns out he was planning to use cheaper materials and cut corners. My instinct was right. If something feels off, it probably is.
How I Compared Quotes (Without Going Insane)
I had six quotes ranging from £52k to £87k for the exact same extension. Here's how I figured out which was actually the best value:
Break Down the Numbers
Create a spreadsheet comparing like-for-like:
- Groundworks and foundations
- Structural work (steels, blockwork)
- Roofing
- Windows and doors
- Electrical and plumbing
- Plastering and decoration
- Kitchen and bathroom installation
Where there are large differences, ask why. Sometimes the cheapest quote excludes things the others include.
Look at the Timeline
A builder quoting 8 weeks for a project others say takes 12 weeks isn't necessarily more efficient—they might be cutting corners or unrealistic about logistics.
Materials Specifications
Are all quotes using comparable materials? Check:
- Insulation thickness and type
- Window specifications (U-values, brand)
- Roof membrane quality
- Finishing materials grade
A quote might be cheaper because they're using lower-spec materials that will cost you in energy bills or durability.
The Contract: What Must Be in Writing
Before any work starts, get a proper contract signed. Essential clauses:
- Scope of work – detailed description of what's included and excluded
- Price and payment schedule – tied to completion stages, not calendar dates
- Start and completion dates – with realistic provisions for weather and material delays
- Penalty clauses – what happens if they overrun significantly
- Variation procedure – how additional work will be quoted and approved
- Insurance details – copies of all relevant policies
- Dispute resolution – arbitration process if you disagree
- Termination clause – how either party can exit and the consequences
Consider having a solicitor review contracts over £50,000. It costs £300-500 and could save you tens of thousands.
The Payment Schedule That Protected Me
What I Learned About Leverage
I paid a builder 50% upfront "to secure materials." Work slowed to a crawl. I had no leverage. He knew I couldn't walk away—he already had my money. Now I never pay more than 10% upfront, and every payment is tied to completed work I can see and verify.
Here's the payment structure that actually works:
- 10-15% deposit – to secure materials and book time
- 25% after foundations and groundworks – inspected and signed off
- 25% after structural work complete – steels in, roof watertight
- 25% after first fix – electrics, plumbing, plastering done
- 15% on practical completion – everything finished to agreed standard
You should always be slightly "ahead" on payments—meaning you've paid for completed work, not work they promise to do next week.
Never pay more than the value of work completed. If the builder needs materials money upfront, ask for receipts and consider buying major items directly.
Site Visits and Checking References
Don't skip this step. Visit an active site if possible. What to observe:
- Tidiness and organization – is the site reasonably clean and materials properly stored?
- Safety practices – are there proper barriers, scaffolding seems secure?
- Workmanship – brickwork neat, cuts precise, attention to detail visible?
- Communication – how do workers interact with homeowners?
When calling references, ask specific questions:
- "What was their best quality?"
- "What was challenging about working with them?"
- "How did they handle problems or mistakes?"
- "Did they finish on time and budget?"
- "Would you use them again?" (Most revealing question)
- "Is there anything you wish you'd known before hiring them?"
Smaller Builders vs Large Companies
Both have advantages. Here's the real difference:
Small Builders (1-5 employees)
Pros:
- Often more flexible and responsive
- Owner directly involved in quality control
- Generally lower overheads = better value
- More personal relationship
Cons:
- May take longer due to juggling multiple jobs
- Less backup if someone's sick or leaves
- Might lack specialist expertise for complex elements
- Financial resources more limited
Larger Companies (10+ employees)
Pros:
- More structured project management
- Greater financial stability
- In-house specialists for different trades
- Better able to handle complex projects
Cons:
- Higher overheads reflected in pricing
- Less flexibility on changes
- You're dealing with project managers, not owners
- Can feel more corporate and less personal
For most home extensions in the £50-150k range, a small to medium builder (3-8 employees) offers the sweet spot of professionalism and value.
This Is Why I Built Ted
After my extension, I had 200+ payments in WhatsApp messages, spreadsheets, and random notes. When I needed to prove what I'd paid for, it took me hours to piece it together. Ted is what I wish I'd had—every payment, receipt, and milestone in one app. No more chaos.
Final Checklist Before You Commit
Before signing anything, verify you have:
- ✓ Proof of public liability insurance (minimum £2m)
- ✓ Companies House check completed (no concerns)
- ✓ At least 3 verified references contacted
- ✓ Detailed written quote with full breakdown
- ✓ Written contract covering all essential clauses
- ✓ Payment schedule tied to completion stages
- ✓ Trade association membership confirmed
- ✓ Site visit completed or recent work observed
Taking the time to choose carefully now saves months of stress and potentially tens of thousands of pounds later.
Final Thought
I spent three weeks interviewing builders. My neighbor thought I was overthinking it. But that three weeks of research saved me from what could have been a £20k disaster. The builder I chose finished on time, on budget, and we still text occasionally. That's what you're looking for—not the cheapest price, but someone you can trust with your home and your money.
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