How to Choose a Builder in Belfast - 12 Questions to Ask

Most bad building jobs were avoidable at the quoting stage. Not because the homeowner failed to spot a villain — genuine cowboys are rarer than the newspapers suggest — but because nobody wrote down what was being bought, and two reasonable people ended up with two different understandings of the same handshake.

These twelve questions are not an interrogation. They are the conversation that stops that happening. A good builder will answer all of them without blinking, and several will be glad you asked, because a customer who understands the job is a customer who does not argue about variations in week six.

Before you let anyone quote

1. Are you VAT registered, and does your price include VAT?

Building work to an existing home is standard-rated at 20 per cent. A VAT-registered builder should give you a price including it and a VAT number you can verify on the government's VAT number checker.

A builder below the threshold is not doing anything wrong and may be genuinely cheaper. A builder who offers you a discount "for cash, no VAT" is offering you a job with no invoice, no paper trail and no comeback. On a £50,000 extension, that is not a saving. It is an uninsured bet.

2. Are you a sole trader or a limited company, and what is the registered name?

Get the exact legal name and, for a company, the number. Look it up on Companies House. You are checking two things: that the entity exists, and that it is not three months old with a director who has left a trail of dissolved companies behind them.

If it is a limited company, payments should go to the company's account, not a personal one.

3. What public liability insurance do you carry, and can I see the certificate?

Ask for the certificate, not the reassurance. Check the cover level — two million pounds is a normal minimum for domestic work — and check the expiry date, because plenty of certificates on file expired last year.

If they employ anyone, they also need employers' liability insurance. If they are cutting a hole in your house, ask whether the works are covered while they are in progress, and check your own buildings policy — most household policies need to be told about significant building work.

4. Can I see two jobs you finished more than a year ago?

Anyone can show you a job they finished last month while everything still looks perfect. You want to see a job that has been through a winter. Ask the previous customer three things: did the price change, did it finish roughly when they said, and did they come back when something needed attention.

That third question is the one that separates a builder from a contractor you will never hear from again.

About the price

5. Can I have the quote broken down by stage?

A single number on one page is not a quote. You want the substructure, the shell, the roof, the windows, first fix, second fix and finishes as separate lines, so that you can compare like with like across three builders and so that stage payments have something to attach to.

If three quotes differ by twenty thousand pounds, a breakdown will show you why within a minute. Usually one of them has not priced the kitchen.

6. What specification have you priced?

The most common cause of a dispute is two people imagining different windows. Get the specification written down: window and door make and material, roof covering, insulation type and thickness, floor finish, sanitaryware allowance, kitchen allowance, decoration.

Give every builder the same written specification and the same drawings. Anything less and you are not comparing prices, you are comparing assumptions.

7. Which items are provisional sums, and how will they be settled?

A provisional sum is an allowance for something that cannot be priced yet — an unknown foundation depth, a kitchen you have not chosen. They are perfectly normal. What is not normal is a quote stuffed with them, because the headline figure then means nothing.

Ask how each one will be settled: on measured cost, on a day rate, with what markup, and with what evidence.

8. Who is submitting and paying for the building control application?

In Northern Ireland, building control is done by your district council — there is no private approved inspector option here, so this is not a choice, it is a task somebody has to own. Establish whether the builder is submitting the application, whether the fee is in their price, and who gives the commencement and stage notices during the job.

If the answer is vague, read our guide to building control in Northern Ireland and then ask again, because the completion certificate at the end is yours, and it is the thing a purchaser's solicitor will ask for.

About the contract and the programme

9. What is the payment schedule, and what is the deposit for?

Stage payments tied to completed work, verified before each payment. A deposit to cover materials ordered up front is reasonable, and it should be a modest proportion of the total with an explanation attached. A demand for thirty per cent before anyone arrives is not a deposit, it is a loan from you to them, unsecured.

Never pay ahead of the work. The only leverage you have on a building site is the money you have not yet handed over.

10. What are the start and finish dates, and what happens if they slip?

Put both in writing, with a note of what would extend them — weather, a variation you asked for, a delay in a council inspection. You are not looking for a penalty clause on a domestic job. You are looking for a builder who is willing to commit to a date at all, because the one who will not is telling you they are already overcommitted elsewhere.

11. Who will actually be on site, and who supervises?

Almost every job uses subcontractors: groundworkers, roofers, an electrician, a plumber, a plasterer. That is normal and it is how the trade works. What matters is who coordinates them, who is on site when there is a decision to make, and how often the person who quoted the job will actually be there.

Ask who your single point of contact is. Then use that person and nobody else, because instructions given directly to a subcontractor are how variations happen without anyone pricing them.

12. What happens when I find a snag six months later?

Ask what guarantee is offered, in writing, and by whom. On larger projects, ask about retention — holding back a small percentage, commonly 2.5 to 5 per cent, for an agreed period after completion, released once the snags are done. It is normal practice in commercial work and entirely reasonable on a big domestic job.

Trade association membership and insurance-backed guarantees are worth having, but understand what they cover. Membership of an association is a badge, not a regulator.

Two things to check yourself

Ring the previous customers, do not just read the reviews. Five minutes on the phone with someone who lived through the job tells you more than fifty online reviews.

Look at a current site if you can. Is it tidy? Are materials stored properly and covered? Is there a skip or a heap? A tidy site is not an aesthetic preference — it correlates almost perfectly with how the work behind the plaster has been done.

The Northern Ireland specifics

There is no licensing scheme for builders in Northern Ireland, or anywhere else in the UK. Anyone can trade as a builder. Trade bodies, trusted trader schemes and quality marks are useful filters, but none of them is a licence, and none of them removes the need for the questions above. Some councils here participate in trusted trader schemes — worth checking whether yours does.

Consumer protection works differently here. Trading standards in Northern Ireland is handled by the Trading Standards Service rather than by council trading standards teams as in Great Britain, with consumer advice available through Consumerline. The Consumer Council for Northern Ireland is the other place to start if something goes wrong.

You have a cancellation right. For a contract agreed in your home — which is most building contracts — consumer contracts law gives you a cooling-off period of 14 days in which you can cancel. A builder should tell you about it in writing. If you want work to start inside that window, that is fine, but it should be agreed explicitly rather than by silence.

Building control is the council's, always. No private inspectors here, so nobody can offer you a faster route through it.

Red flags

• Pressure to decide today, or a price that expires this evening
• A discount for cash with no invoice
• A large payment demanded before any work starts
• No written quote, no specification, no address on the paperwork
• Payment requested to a personal account for a limited company
• A price dramatically below the other two — the money has been saved somewhere, and it is usually in the foundations, the insulation or the fact that they have not priced half of it

One last question, for yourself

Do you know what this should cost?

You cannot judge a quote without a benchmark. Run your project through the extension cost calculator or the relevant one for your job first, so that when three prices land on the kitchen table you already know which one is the outlier and which is the market. Our guides to extension costs in Belfast, loft conversion costs in Northern Ireland and driveway costs here give the 2026 rates behind those numbers.

Then, if you want three prices without ringing round, tell us about the job and we will put it in front of local builders.

Reviewed August 2026. General guidance, not legal advice.