The short answer
Choose a garage conversion builder who is FMB-registered or works with building control, gives an itemised written quote after a site visit, can show references and recent work, and sets out the job in a clear written contract. Check that they handle the building regulations sign-off, carry appropriate insurance, and are happy to put the scope, price, timescale and guarantee in writing. The cheapest quote is not automatically the best; weigh price against credentials, clarity and reputation.
Choosing the right contractor is the single biggest factor in a conversion going well. A good builder turns a cold garage into a warm, signed-off room with minimal stress; the wrong one can leave problems that surface at resale. This guide covers the checks that matter. These are general pointers, not advice for your specific job. When you are ready to gather prices, see how to get garage conversion quotes; for what the work involves, see what is involved.
Choosing a builder at a glance
- Registration FMB or building-control-approved
- Quote Itemised, after a site visit
- Building control They handle sign-off
- Evidence References & recent work
- Insurance Appropriate cover
- Contract Scope, price, time, guarantee
Credentials and building control
Start with credentials. An FMB-registered builder has been vetted and signs up to a code of practice, and a specialist who routinely works with building control will manage the inspections and completion certificate for you. Confirm they will arrange the building regulations sign-off, because that certificate is what buyers and their solicitors expect at resale — see building regulations for a garage conversion. Check they carry appropriate insurance and ask how electrical work will be certified under Part P.
Evidence, quotes and contract
Ask to see references and recent garage conversions, and follow them up. Insist on an itemised written quote after a site visit rather than a phone price, so you can compare like with like. Before work starts, get a written contract setting out the scope, price, payment schedule, timescale and guarantee. A builder who is reluctant to put these in writing, or who pushes for a large upfront payment, is a warning sign.
| Check | Why it matters |
|---|---|
| FMB registration / building control | Vetting, code of practice, proper sign-off |
| Itemised written quote | Lets you compare fairly and spot gaps |
| References & recent work | Evidence the builder delivers |
| Insurance & Part P | Cover and certified electrics |
| Written contract | Scope, price, timescale and guarantee agreed |
Comparing on more than price
With your quotes in hand, weigh more than the headline figure. The cheapest quote can mean a thinner scope — less insulation, omitted making good, or no allowance for the floor — while the dearest is not automatically the safest. Look at how thorough the survey was, how clear the quote and contract are, and what independent reviews say. This is general information, not advice for your specific job; choose an FMB-registered or building-control-approved garage conversion specialist who handles building control, and check the details before you commit.
Compare garage conversion quotes
Apply these checks, then compare itemised quotes from FMB-registered or building-control-approved specialists in your area on a like-for-like brief.
Frequently asked questions
What should I check before hiring a garage conversion builder?
Check they are FMB-registered or work with building control, will arrange the building regulations sign-off, carry appropriate insurance, can show references and recent work, and will provide an itemised written quote and a clear contract covering scope, price, timescale and guarantee.
Should the builder handle building control?
Ideally, yes. A specialist who works with building control will manage the inspections and obtain the completion certificate, which buyers and their solicitors expect at resale. Confirm who is responsible for notifying and signing off the work before you start.
Is the cheapest quote the best choice?
Not necessarily. A lower price can mean a thinner scope — less insulation, omitted making good or no floor allowance — while the most expensive is not automatically the safest. Compare itemised quotes on the same brief and weigh credentials, clarity and reviews, not just the figure.
Sources & further reading
- Federation of Master Builders (FMB) — finding and checking registered builders
- Local authority Building Control — inspection and completion certificates
- GOV.UK / Building Regulations Approved Documents — standards and Part P electrics
- Planning Portal — permitted development for garage conversions
This is general information, not advice for your specific job. The right builder depends on your project and area, so check credentials, references and contracts before you commit. The work should be carried out by an FMB-registered or building-control-approved garage conversion specialist. We are an independent information and introduction service, not a builder.