12 essential questions to ask every garden room supplier, red flags to watch for, how to compare quotes on a like-for-like basis, and what separates good suppliers from bad ones.
How to Choose a Garden Room Supplier: 12 Questions to Ask
The garden room market in the UK has grown rapidly, and with it the number of suppliers — from established companies with decades of experience to new entrants who may have built only a handful of rooms. The quality, specification, and after-sales support varies enormously, and choosing the wrong supplier can result in a building that leaks, a guarantee that is worthless, or a project that is never completed.
This guide gives you a practical framework for evaluating suppliers and the 12 questions you should ask every company before committing.
Why Choosing the Right Supplier Matters
A garden room is a significant investment — typically £15,000–£50,000 — and unlike buying a product from a shop, you cannot return it if it is not right. The building will be in your garden for 20 years or more, so the quality of materials, construction, and weatherproofing matters enormously.
The garden room industry is largely unregulated. There is no mandatory licensing, no required qualifications, and no industry body that all suppliers must belong to. This means the responsibility for due diligence falls on you, the homeowner.
12 Questions to Ask Every Supplier
1. How long have you been trading?
Look for companies that have been trading for at least 3 years, ideally 5 or more. New companies are not necessarily bad, but a track record gives you confidence that the business is stable and that their buildings have been tested by a few winters. Check Companies House for the company's incorporation date and filing history.
2. Can you provide references from previous customers?
A reputable supplier should be happy to provide contact details for 2–3 previous customers who you can speak to directly. Ask the references about the quality of the build, whether the project was completed on time and to budget, and how the supplier handled any issues that arose.
3. Can I visit a completed garden room or showroom?
Seeing a completed building in person is far more informative than looking at photographs. Many suppliers have show sites or showrooms where you can see the quality of construction, the finish of the cladding and internal lining, and the feel of the space. If a supplier cannot show you a completed building, that is a concern.
4. What insulation do you use, and what are the U-values?
This is one of the most important technical questions. A good supplier should be able to tell you the insulation material (PIR, mineral wool, SIP), the thickness in walls, floor, and roof, and the resulting U-values for each element. Aim for wall U-values of 0.30 W/m²K or better for year-round use. If a supplier cannot answer this question clearly, they may not be building to a high enough standard. For more on insulation, see our insulation guide.
5. What is included in the quoted price?
This is where many homeowners get caught out. Ask specifically whether the price includes: foundations/groundworks, electrical connection from the house, internal lining (plasterboard or timber), flooring, lighting and sockets, heating, delivery, and installation. Items that are excluded can add £3,000–£15,000 to the total cost. For a full breakdown of costs, see our cost guide.
6. What is NOT included?
The flip side of question 5. Ask the supplier to list everything that is excluded from the quoted price. Common exclusions include foundations, electrics, internal decoration, landscaping, and building control fees (if applicable).
7. What guarantee do you offer?
Look for a minimum 10-year structural guarantee on the building, with separate guarantees on components such as windows (typically 5–10 years), electrics (typically 2–5 years), and the roof membrane (typically 10–20 years). Ask whether the guarantee is insurance-backed — this means you are protected even if the company ceases trading. An insurance-backed guarantee costs the supplier more but provides genuine peace of mind.
8. Do you carry out a site survey before quoting?
A reputable supplier will always visit your site before providing a final quote. The site survey allows them to assess access, ground conditions, drainage, proximity to boundaries and trees, and any other factors that might affect the build. A supplier who quotes without visiting the site is likely to add unexpected costs later.
9. What foundations do you recommend for my site?
A good supplier will advise on the most appropriate foundation type based on your soil conditions, access, and budget. They should be able to explain the pros and cons of different options (concrete slab, ground screws, pads) and either provide the groundworks themselves or recommend a trusted subcontractor. See our foundations guide.
10. Who does the electrical installation?
The electrical installation must be carried out by a Part P registered electrician. Ask whether the supplier uses their own electrician or a subcontractor, and whether the electrical work is included in the quoted price. The electrician should provide a Part P certificate (Building Regulations compliance certificate) on completion. See our electrics guide.
11. What is your current lead time?
Lead times vary from 3 weeks to 12 weeks or more depending on the supplier's order book and the time of year. Spring and summer are peak season, and popular suppliers may have longer lead times. If you have a deadline, confirm the lead time in writing before placing your order.
12. What happens if there is a problem after installation?
Ask about the supplier's after-sales process. How do you report a problem? What is the response time? Do they have a dedicated after-sales team? A good supplier will have a clear process for handling snags and warranty claims.
Red Flags to Watch For
Be cautious if a supplier exhibits any of the following warning signs.
No site survey: A supplier who quotes without visiting your site cannot give you an accurate price and is likely to add unexpected costs later.
Vague specifications: If a supplier cannot tell you the insulation type, thickness, and U-values, they are either not building to a high standard or not being transparent about what you are getting.
No written guarantee: A verbal promise of "we'll sort it out" is worthless. Insist on a written guarantee with clear terms.
Pressure to sign quickly: Legitimate suppliers do not pressure you into signing a contract on the spot. Take time to compare quotes and check references.
Unusually low prices: If a quote is significantly cheaper than competitors, find out why. It may be because the specification is lower, items are excluded, or the supplier is cutting corners.
No fixed business address: Check that the supplier has a permanent business address (not just a PO box or residential address) and is registered at Companies House.
Large upfront deposits: A deposit of 10–20% is normal. Be wary of suppliers who ask for 50% or more upfront before any work has begun.
Getting and Comparing Quotes
Get quotes from at least three suppliers and compare them on a like-for-like basis. Create a simple spreadsheet listing what each quote includes and excludes, the insulation specification, the guarantee terms, and the total price including all extras.
Do not automatically choose the cheapest quote. The best value is the supplier who offers the right specification, a solid guarantee, good references, and a fair price — not necessarily the lowest one.
Next Steps
You can browse our supplier directory to find garden room companies serving your area, or use our compare tool to evaluate suppliers side by side. Our free planning wizard generates a personalised report that helps you understand what specification and budget to aim for, which makes comparing quotes much easier.