Two garage conversion quotes land on your doormat. One says £9,000, the other £15,000. What is actually different? Comparing garage conversion quotes is hard because the price often depends on what each builder has chosen to include: insulation, damp proofing, electrics, building control and the paperwork you need when you sell. This guide shows what a fair garage conversion quote covers, what is often missing and how to compare garage conversion quotes like for like.
What Is a Garage Conversion Quote (and What Should It Cover)?
What Should a Garage Conversion Quote Include?
If you are asking what a garage conversion quote should include, use the groups below. Each one is a place where quotes commonly differ. This doubles as a garage conversion quote checklist.
| Group | What to look for |
|---|---|
| Structure | Garage door infill (bricking up), lintels, new wall, foundations and floor level |
| Insulation and damp | Floor, wall and roof insulation, and a damp proof membrane. Named products, not just “insulated” |
| Electrics, heating, lighting | New circuits, consumer unit changes, sockets, radiators or other heating, lighting |
| Windows and doors | Number, size and type of new windows and doors, including glazing |
| Finishes | Plastering, flooring, skirting, painting and decoration |
| Plumbing and drainage | Only if a bathroom, en-suite or utility is planned |
| Regulatory | Building control fees, drawings, any structural engineer’s report, completion certificate |
| Site costs | Waste removal, skip hire and VAT |
If a line only says “conversion works”, ask for the detail. Our guide on why “included in the price” can cause problems explains why vague wording matters.
Building Regulations vs Planning Permission: What Your Quote Should Say
These are separate. According to the Planning Portal, converting a garage into habitable space normally needs building regulations approval. Separately, planning permission is not usually required if the work is internal and does not enlarge the building. Planning can still be needed in some cases, for example where a condition on the original permission says the garage must be kept for parking, as some councils explain, or where a detached garage becomes a self-contained living space.
This guidance is England-focused. Rules differ in Scotland, Wales and Northern Ireland, and your local authority has the final say. Your quote should say who handles garage conversion building regulations, who pays the building control fees and whether you will receive a garage conversion completion certificate. That certificate matters when you sell, because buyers’ solicitors often ask for it.
Is building regs included in a garage conversion quote? Not always. Regulatory costs such as building control fees, drawings and any structural engineer’s report are sometimes outside the builder’s price, so ask who pays.
Why Garage Conversion Quotes Vary So Much
Why are garage conversion quotes so different? In practice, it comes down to scope and specification:
- Insulation and damp: thicker or better-specified insulation, and a proper damp proof membrane, cost more than a minimal job.
- Windows and doors: the number, size and quality of the new openings.
- Building control: included in one quote, left to you in another.
- Finishes: plastered and decorated, or left ready for others.
- Allowances: provisional sums or PC sums for items not yet chosen.
- VAT: included in some quotes, added later in others.
If one price looks far lower, read builder quote much cheaper than the others? before you decide. A garage conversion quote too cheap to be true usually means something is missing, though not always.
Worked Example: Two Quotes, Same Garage
These figures are illustrative only, not UK market prices or real quotes.
| Item | Quote A (£14,500) | Quote B (£11,000) |
|---|---|---|
| Building control fees | Included | Excluded |
| Insulation specification | Named products, floor and walls | “Insulated”, no detail |
| Electrics | New circuit and sockets | Sockets only |
| Completion certificate | Included | Not mentioned |
| Flooring and decoration | Included | Excluded |
| Skip and waste removal | Included | Excluded |
Quote B is £3,500 cheaper, but it leaves several items unpriced. Before comparing totals, ask Builder B to confirm and price each gap in writing. Do not assume the cheaper quote is worse, or the dearer one better. A clearer scope simply makes the comparison fair. This is also a good place to check any PC sum or provisional sum.
How to Compare Garage Conversion Quotes Like for Like
- Give every builder the same brief, including the intended use of the room.
- Ask for itemised quotes, not one lump sum.
- List every exclusion and ask what each would cost.
- Check allowances, such as a PC sum for flooring or windows, and how overspend is handled.
- Put VAT on the same basis for every quote.
- Compare insulation, damp proofing and electrical specifications by name.
- Compare programmes, payment stages and guarantees.
- Get answers in writing, then compare the revised totals.
How many quotes for a garage conversion? Three is a common starting point, but the number matters less than whether they cover the same scope. Garage conversion quote vs estimate: a quote should be a firm price for a defined scope, while an estimate can change. Our guide on quote or estimate explains the difference, and how to compare builder quotes covers the wider method.
Comparison Checklist Table
Use this as a garage conversion quote template in a spreadsheet, one column per builder.
| What to check | Builder 1 | Builder 2 | Builder 3 |
|---|---|---|---|
| Total price and VAT basis | £14,500 (VAT basis to confirm) | £11,000 (VAT basis to confirm) | £12,800, excl. VAT |
| Building control fees | Included | Excluded | Included |
| Structural engineer, if needed | Not stated | Not stated | Excluded, priced separately |
| Door infill and lintels | Not stated | Not stated | Included |
| Floor insulation and damp proofing | Named products, floor and walls | “Insulated”, no detail | Named products, floor only |
| Electrics and heating | New circuit and sockets | Sockets only | New circuit, sockets and radiator |
| Windows and doors | Not stated | Not stated | Included, 1 new window |
| Flooring and decoration | Included | Excluded | Plastering only |
| Waste removal | Included (skip and waste) | Excluded | Not mentioned |
| Completion certificate | Included | Not mentioned | Not provided |
Garage Conversion Quote Exclusions to Watch For
Garage conversion quote exclusions are rarely hidden on purpose, but they are easy to miss. Look for wording such as “by others”, “subject to inspection” or “client to arrange”. Common examples include a structural engineer’s report, building control fees, redecoration, new heating, and ceiling height problems that only appear once the work starts. Ask the builder to say whether each is included, excluded or priced separately, and put that in writing.
Red Flags in a Garage Conversion Quote
- Building regulations not mentioned
- Vague “conversion works” with no breakdown
- No insulation or damp proofing specification
- A large upfront deposit with no stages
- Cash-only requests
- No proof of insurance when asked
One flag alone is a reason to ask questions, not proof of a problem.
Questions to Ask Your Builder Before You Accept
- Does the price include building control fees and drawings?
- Will I receive a completion certificate?
- Is a structural engineer’s report needed, and who pays?
- What insulation and damp proofing will you use?
- How will the garage door opening be infilled?
- What electrical work is included?
- Are windows, doors and finishes included?
- Are waste removal and skip hire included?
- Is VAT included in this price?
- How will extra work be priced and agreed in writing?
Payment Stages and Deposit: What Is Normal?
There is no single answer. Ask what any deposit covers, whether payments are tied to stages of completed work and when the final payment is due. Put the terms in writing before you sign. See how much deposit a builder should ask for for what to look for.
How ScopeCheck Helps You Compare Garage Conversion Quotes
Once you have two or more garage conversion quotes, the hard part is lining them up. ScopeCheck lets you upload 2–5 quotes for the same job as PDFs, photos or pasted text. The report shows what each quote includes, what is missing and what to ask your builder, before you pay a deposit.
- Items marked as included, excluded, unclear or not mentioned
- VAT basis shown for every quote, never quietly adjusted
- An estimate of the cost of missing work, clearly separate from quoted prices
- Questions to send to each builder, and a dated report you can print or share
- Your own job list as the starting point, so every quote is checked against the same list
ScopeCheck does not take money from traders, and your quotes stay private and are never shared with traders. You can try a free preview of 2 quotes with no sign-up. See an example report, read how it works, or browse the compare quotes page. For related jobs, see loft conversion quotes and extension quotes.
ScopeCheck is an AI-assisted decision aid. It does not inspect your home, verify a builder or guarantee costs, and AI can miss details, so check the original quote wording. It is provided by Dashient Ltd, a UK digital growth agency.
Frequently Asked Questions
What should a garage conversion quote include?
Structural work, insulation, damp proofing, electrics, windows, finishes, regulatory costs, waste removal and VAT, plus clear exclusions and payment terms.
Is building regs included in a garage conversion quote?
Not always. Check whether building control fees, drawings and any engineer’s report are included, and who arranges the completion certificate.
Do I need planning permission for a garage conversion?
Often not, if the work is internal and does not enlarge the building, but conditions on the original permission may apply. Check with your local planning authority.
How much deposit should I pay for a garage conversion?
There is no single answer. Ask what it covers, whether payments are staged and get terms in writing.