The short answer
To choose a garden room company, compare three itemised, supplied-and-fitted quotes on specification rather than headline price, and check insurance, warranty, references and a clear written contract. Ask what insulation and glazing each quote includes, confirm the electrics are certified under Building Regulations Part P, and make sure who is responsible for planning, the base and snagging is written down. A good company is happy to itemise and answer questions; a poor one quotes a single round number and pushes for a quick deposit. These are general pointers, not an endorsement of any builder — see the main cost guide for typical figures.
A garden room is a significant purchase, often costing as much as a small car, yet the market is fragmented and unregulated. Some companies are long-established specialists with their own factories; others are one-person operations or general builders adding garden rooms as a sideline. The quality and after-sales experience varies enormously, and because the most important parts — insulation, the frame, the electrics — are hidden once the room is finished, it can be hard to tell good from bad until something goes wrong. This guide sets out how to compare companies fairly and what to insist on before you pay a deposit.
What to check at a glance
- Quotes to compare At least three, itemised
- Electrics Part P certified by the company
- Insurance Public liability in place
- Warranty Structure and weatherproofing, in writing
- Contract Written scope, stages and payments
- References Recent, local, ideally visited
Compare quotes on specification, not price
The single most useful thing you can do is get three quotes and lay them side by side. The trap is comparing them on the bottom-line figure alone, because a cheaper quote often hides a thinner specification: less insulation, single rather than double glazing on a door, a basic base instead of a proper one, or electrics left for you to arrange. Ask each company to itemise the base, the insulation values for floor, walls and roof, the glazing, the cladding, the roof covering and the electrical fit-out. Once the quotes are itemised, real differences appear — and a slightly dearer quote with a better thermal envelope is usually the better buy, because the insulation and glazing are the parts you cannot upgrade later.
| Ask about | Good sign | Warning sign |
|---|---|---|
| The quote | Itemised, specification listed | One round number, no detail |
| Electrics | Included and Part P certified | “You arrange your own” |
| The base | Specified to ground conditions | Assumed flat, not surveyed |
| Planning | Will advise / supply drawings | “Don’t worry about it” |
| Deposit | Reasonable, staged payments | Large cash deposit, pay in full up front |
Insurance, warranty and the contract
Check that the company holds public liability insurance — if a workman is injured or your property is damaged during the build, this matters. Ask what warranty is offered and get it in writing: a reputable garden room company typically warrants the structure and weatherproofing for a number of years, separate from manufacturer warranties on windows or doors. Insist on a written contract that sets out exactly what is included, the build stages, the payment schedule and what happens if things slip. Be wary of any company asking for a large deposit in cash or full payment before work starts; staged payments tied to milestones protect both sides. A clear contract also settles who is responsible for the base, for electrics and Wi-Fi, and for any planning drawings.
Responsibility and planning
Make sure it is written down who handles what. Most reputable companies will advise on whether your room is likely to be permitted development and can supply drawings if you need a Lawful Development Certificate, but the legal responsibility for planning rests with you as the homeowner — a company saying “don’t worry about planning” is a warning sign, not reassurance. The same applies to Building Regulations: if you plan to sleep in the room or it exceeds the size thresholds, regulations apply and someone must arrange the approval. Confirm all of this before signing. This is general guidance, not an endorsement of any particular company; always do your own checks, confirm planning with your Local Planning Authority, and read the contract carefully before paying a deposit.
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Frequently asked questions
How many garden room quotes should I get?
At least three, and ask for each to be itemised. Comparing three quotes on specification — insulation, glazing, base and electrics — rather than headline price is the best way to judge value and spot a thin specification hiding behind a low number.
What should be in a garden room contract?
A written scope of exactly what is included, the build stages, the payment schedule, the warranty, and who is responsible for the base, electrics and any planning drawings. Avoid companies that want a large cash deposit or full payment before work begins.
Should a garden room company sort out planning?
A good company will advise on whether your room is likely to be permitted development and can supply drawings, but the legal responsibility for planning stays with you as the homeowner. Treat “don’t worry about planning” as a warning sign and confirm the position with your Local Planning Authority.
Is a cheaper garden room quote a bad sign?
Not necessarily, but a cheaper quote often reflects a thinner specification — less insulation, a basic base, or electrics left for you to arrange. Itemise the quotes and compare like for like before deciding; the dearer quote is sometimes better value once the specification is clear.
Sources & further reading
- GOV.UK Planning Portal — outbuildings, permitted development and Lawful Development Certificates
- GOV.UK / Building Regulations Approved Documents L and P — energy efficiency and electrical safety
- Trade and industry guidance — typical garden room contracts, warranties and specification
- Your Local Planning Authority — for confirmation of planning status
This is general information, not advice for your specific property or project, and not an endorsement of any company. Always carry out your own checks, confirm planning with your Local Planning Authority, and read any contract carefully before paying a deposit.