Finding a Builder in Caernarfon
Hiring a builder is one of the biggest decisions you'll make as a homeowner. Whether you're extending a terraced cottage, renovating a Victorian semi, or doing a full remodel, getting the right person for the job matters. This guide walks you through what to expect, what to look for, and how to avoid the common pitfalls.
Caernarfon has a solid local building trade. The town's mix of older properties and newer estates means builders here are used to everything from period stonework repairs to modern extensions. Most reputable builders in the area know the local authority planning process, building control requirements, and the quirks of the local housing stock.
The key is doing your homework before you sign anything. A good builder will have references you can check, the right insurance and accreditations, and will give you a clear, detailed quote. They'll also be upfront about timelines and what could go wrong. In this guide, we'll cover what to expect cost-wise, which accreditations actually matter, what's specific to building in Caernarfon, and exactly what questions to ask before you hire.
What Building Work Costs in 2026
Building costs vary wildly depending on what you're doing, the complexity of the work, and whether there are hidden problems once the walls come down. Here's a realistic breakdown for common projects in 2026:
Extensions and conversions: A single-storey rear extension typically runs £1,500–£2,500 per square metre, depending on spec and ground conditions. A two-storey extension is usually £2,000–£3,200 per square metre. Loft conversions range from £15,000–£35,000 depending on roof structure and whether you need structural work.
General building work: Pointing and repointing external stonework costs £20–£40 per square metre. Roof repairs start at £150–£400 per square metre for stripping and re-laying. Chimney repairs can be £800–£2,500 depending on what's needed. Underpinning (common in older Caernarfon properties) typically costs £3,000–£8,000 per section.
New builds and major works: If you're building new or doing a full structural overhaul, budget £150–£250 per square metre for labour alone, plus materials.
Labour: A general builder charges £250–£450 per day; specialist tradespeople (stonemasons, roofers) might be £300–£550. Always ask whether quoted prices include VAT—they should.
These are ballpark figures. Always get at least three written quotes and never accept a quote with no detail. If something seems unusually cheap, ask why. There's usually a reason.
Accreditations That Matter
Not all accreditations are equal. Here's what you should be looking for:
FMB (Federation of Master Builders): This is the gold standard for builders in the UK. FMB members are vetted, carry proper insurance, and sign up to a code of conduct. If your builder is FMB-registered, that's a strong signal they're professional and accountable. The FMB also operates a dispute resolution scheme if things go wrong.
TrustMark: A government-backed scheme that certifies traders and businesses. TrustMark traders must have proper qualifications, insurance, and trading history. They're also vetted for complaints and compliance. It's worth checking the TrustMark register to verify a builder's status.
Which? Trusted Trader: The consumer organisation's endorsement scheme. Builders on this list have been checked for customer service standards, insurance, and qualifications. It's not as rigorous as some schemes, but it's a useful filter.
Building Control approval: This isn't an accreditation of the builder, but it matters hugely. Any structural work, extensions, or conversions need Building Control sign-off from Gwynedd Council (or whoever approves it locally). A good builder will arrange this and budget for it. If they say Building Control isn't needed, be very suspicious.
NHBC Warranty or LABC: If the builder is new-build certified, these warranties protect you if defects appear after handover. Check they're active and current.
Always ask to see original certificates—photos on a website aren't enough. Ring the scheme directly if you're unsure.
Building in Caernarfon: What's Different Here
Caernarfon's housing stock is distinctive, and that affects the kind of problems builders encounter and how they need to approach work.
Much of the town consists of solid-wall Victorian and Edwardian terraces and semis, built with stone and lime mortar. These are wonderful properties but they have quirks. Rising damp is common because the older mortar is porous and there are often no damp-proof courses. Modern cement-based repairs can actually make damp worse by trapping moisture. A builder who knows Caernarfon will understand lime mortar repointing, breathing walls, and how to fix damp the right way—not always the quick way.
The town sits on varied geology, and some roads have clay soils prone to subsidence. If you're extending or underpinning, a structural engineer's report is essential. Local builders are usually familiar with which streets have issues and what Gwynedd Building Control typically asks for.
Caernarfon also has planning sensitivity around the castle and conservation areas. If your property is near the castle or within a designated area, planning permission can be strict about style, materials, and appearance. Local builders often know the planning officers and what flies—a massive help when you're designing an extension.
Weather is also a factor. The Welsh coast gets exposed to wind and rain. Builders here understand pitched roofs need proper ventilation, guttering needs regular clearance, and external pointing needs to be robust. It's worth asking a local builder what they'd do differently because of Caernarfon's climate and building types.
How to Hire the Right Builder
Once you've drawn up a shortlist, follow this process:
Get it in writing: Never agree to work on a handshake or a phone call. Get a written quote with scope of work, timeline, payment schedule, and insurance details. The quote should reference any site survey or specification you've provided.
Check references: Ask for three recent customers and contact them. Don't just ask "Were you happy?"—ask about timekeeping, how they handled problems, cleanliness, and whether the final bill matched the quote. References matter more than you'd think.
Verify insurance: Ask for proof of public liability insurance (minimum £6 million for most building work) and employer's liability if they have staff. Check the certificate is current and covers the type of work you need.
Use a contract: For anything over a few hundred pounds, you should have a written contract. It doesn't need to be fancy, but it should cover scope, cost, timelines, payment terms, and dispute resolution. The FMB publishes standard contract templates that are fair to both sides.
Agree payment terms: Never pay 100% upfront. Standard is a deposit (10–25%), progress payments as work completes, and final payment on completion. Retain 5–10% for 28 days after finishing to ensure snag lists are dealt with.
Plan for changes: Building work often uncovers surprises. Agree in writing how changes will be priced and approved before work starts. This stops arguments later.
Get it insured: If the builder is on your property, they need insurance. Your home insurance may not cover accidental damage by contractors.
Questions to Ask Every Builder
Before you hire, ask these questions and listen carefully to the answers:
How long have you been building in Caernarfon? Experience with local properties and council processes matters. Someone familiar with the area will anticipate problems.
Can you give me three references from similar projects in the last two years? Get names, contact details, and project descriptions. Ring them.
What's your liability insurance and is it current? Get the certificate. Check it covers the type of work you need.
Who's responsible for Building Control? They should arrange and pay for Building Control inspections. It's their legal duty.
What happens if you find unexpected problems? For example, rotten timber or unstable ground. How do you handle it? A good builder has a process and won't just add £5,000 to the bill without explanation.
Are you a member of FMB, TrustMark, or Which? Trusted Trader? Verify it. These memberships mean recourse if things go wrong.
What's the payment schedule? Deposit, progress payments, final payment—and when's final payment due? Never pay 100% before work is done.
How do you manage site safety and cleanliness? On-site welfare facilities, dust control, safe access—these aren't glamorous but they reflect professionalism.
What's your guarantee or warranty? Most builders offer 12 months on workmanship. Building control provides structural warranty. Know what's covered.