28mm, 44mm or 70mm? Made to Measure Garden Rooms in the UK

Choose a made to measure garden room when you need an exact fit, proper insulation and a layout that suits how you actually live or work. You’ll pay more than you would for a basic flat-pack cabin, but you get better insulation, a longer lifespan and a room that fits your garden instead of the other way round. Read on for sizes, costs, planning rules and a simple checklist before you order.

TL;DR:

• For daily use throughout the year, choose a 70mm insulated wall and double glazing; 44mm suits part time offices, while 28mm fits seasonal rooms.
• Within 2 metres of a boundary, outbuildings face a 2.5 metre height limit; combined coverage cannot exceed 50% of the area around the original house.
• Under 15 square metres, rooms are often exempt; from 15 to 30, boundary distance or noncombustible materials matter, and sleeping space triggers Building Regulations approval.
• Basic cabins without insulation cost roughly £3,000 to £5,000; bespoke insulated rooms for year round use typically start around £10,000, before potential extras.
• Get itemized quotes that state whether VAT, foundations, groundworks, electrical connections, and planning or Building Control fees are included, since headline prices may omit them.

Table of Contents

• Which uses need which features
• Choosing sizes, wall thickness, insulation and glazing
• Planning permission and Building Regulations explained simply
• What a made to measure garden room actually costs
• Foundations, site preparation and the installation process
• How to brief and get the best quote
• Practical tips from building bespoke garden rooms
• Questions to ask before you order
• Payment and deposit terms for bespoke orders
• From order to completion: what to expect
• When bespoke is worth the extra cost
• Getting your own made to measure garden room
• FAQ
• Sources

Which uses need which features

Before you ask for a quote, think about what you’ll actually do in the room. A garden office needs different things from a gym, and a gym needs different things from a summer studio. Getting this right at the brief stage saves you from paying for features you don’t need, or missing ones you do.

A home office is used most of the year, often all day, so it needs good insulation and a heating plan that keeps running costs sensible. A studio for art, music or a workshop might need higher floor loading if you’re storing heavy equipment or a kiln, plus more electrical sockets than a standard room. A garden gym needs a durable, non-slip floor finish and proper ventilation, since exercise generates heat and moisture that ordinary cabins aren’t built to handle. An annexe for visiting family sits in a different category altogether: once you add sleeping space or plumbing, your project usually becomes “habitable accommodation” in the eyes of Building Control, which brings a stricter set of rules into play.

Layout matters just as much as use. Glazing placement affects both light and privacy, especially if your garden room backs onto a neighbour’s boundary. Multi-room layouts, such as an office with a separate storage area, need careful thought about where partitions go so you don’t lose useful floor space to corridors.

• Home office: good insulation, reliable heating and enough sockets for a desk setup.
• Studio or workshop: higher floor loading and extra power points for equipment.
• Garden gym: durable flooring and ventilation to manage heat and moisture.
• Annexe with sleeping or plumbing: treated as habitable space, triggering fuller Building Regulations checks.

Working through this list before you contact a supplier means your quote request already matches your actual needs, which makes it far easier to compare one supplier’s numbers against another’s.

Choosing sizes, wall thickness, insulation and glazing

This is where a made to measure build earns its name. Every choice here changes how the room feels day to day, and how much you’ll pay for it.

Wall thickness is one of the first decisions you’ll make, and it affects both warmth and noise. A 28mm wall suits a light-use summer house where you’re not fussed about winter comfort. A 44mm wall is a common middle ground, giving noticeably better heat retention for a part-time office or hobby room. A 70mm wall, often built with an insulated stud construction rather than solid log, is the usual choice for anyone planning to use the room through a full winter, since it holds heat and cuts down on outside noise far more effectively.

Insulation itself deserves its own conversation with your supplier. Ask for a target U-value, not just a vague promise of “well insulated”, and ask what layers make up the wall: insulation board, a vapour control layer and an internal lining are all standard parts of a properly built-up wall. Which? recommends insulated, double-glazed garden rooms for anyone wanting year-round comfort, rather than a single-skin timber cabin.

Glazing choices follow the same logic. Double glazing with a low-E coating keeps heat in during winter and out during summer, and it’s worth asking whether doors come with multi-point locking for security, particularly if the room will hold a laptop, tools or music equipment overnight.

Cladding and external finish round off the specification. Factory-applied paint finishes tend to last longer and need less upkeep than untreated timber, though untreated cladding weathers to an attractive silver-grey over time if you don’t mind the natural look. Composite cladding options trade some of that traditional appearance for lower long-term maintenance.

• 28mm wall: fine for light, occasional use such as storage or a summer retreat.
• 44mm wall: a solid middle choice for part-time offices and hobby rooms.
• 70mm insulated wall: the usual choice for daily, year-round use.
• Double glazing with low-E coating: keeps the room comfortable across seasons.
• Factory-painted cladding: lower maintenance than untreated timber over time.

Pro Tip: Ask every supplier for the same U-value target and the same wall build-up description, so you’re comparing like for like rather than one firm’s marketing language against another’s.

Planning permission and Building Regulations explained simply

Most garden rooms don’t need planning permission, but it pays to check the detail before you order rather than after.

Permitted development rights let most homeowners build outbuildings without formal planning consent, provided you stay within certain limits. Gov sets a height limit of 2.5 metres for any outbuilding within 2 metres of a boundary, and states that outbuildings must not cover more than 50% of the total area around the original house.

Building Regulations are a separate matter from planning permission, and this is where many buyers get confused. According to Building Regulations guidance, garden buildings under 15 square metres are often exempt altogether. Buildings between 15 and 30 square metres may still be exempt, but only if they sit at least 1 metre from any boundary or are built from substantially non-combustible materials. Anything over 30 square metres, or any room that includes sleeping accommodation, usually needs full Building Regulations compliance.

Even a planning-exempt garden room can still need Building Regulations sign-off once you add insulation, heating or electrical sockets, according to practical guidance on garden room regulations, so don’t assume a small room is automatically free of paperwork.

• Check your garden’s total outbuilding coverage against the 50% rule before finalising a size.
• Measure your proposed footprint against the 15m² and 30m² Building Regulations thresholds.
• Ask whether your room’s distance from any boundary affects its exemption status.
• Request Part P certification for any electrical work, since this applies regardless of the room’s size.

A quick call to your local planning department, alongside early advice from Building Control, costs nothing and can save you from a costly redesign later.

What a made to measure garden room actually costs

Prices vary enormously depending on size, insulation and finish, so it helps to think in bands rather than chasing a single figure.

Which? puts simple, uninsulated self-assembly cabins at roughly £3,000 to £5,000, which suits light, seasonal use such as storage or an occasional summer retreat. Luxury turnkey builds, with high-end internal finishes and full services included, typically cost more, and the final figure depends heavily on size and specification.

Whatever band you’re in, watch for what’s missing from a quote rather than just what’s included. Common exclusions are VAT, groundworks and foundation preparation, electrical connection back to your house, drainage, and any planning or Building Control fees. These costs aren’t hidden on purpose, but they’re easy to overlook if you’re comparing headline prices from different suppliers.

• Ask whether VAT is included in the headline price or added afterwards.
• Check if groundworks and foundation preparation are part of the quote or a separate cost.
• Confirm who arranges and pays for the electrical connection to your home’s supply.
• Ask whether planning or Building Control fees are factored into the total.

Pro Tip: Divide the full, all-in quote by the room’s internal floor area to get a true cost per square metre, then use that figure to compare suppliers fairly, rather than comparing headline prices for rooms of different sizes.

An itemised quote, broken down by structure, insulation, glazing, electrics and groundworks, makes it far easier to see where your money is going and to spot a supplier who’s bundled in extras you didn’t ask for.

Foundations, site preparation and the installation process

Getting the groundwork right matters as much as the cabin itself, since even the best-built room will struggle on an uneven or inadequate base.

There are three common foundation options. A concrete slab offers the most stable base and suits larger or heavier bespoke builds, though it takes longer to prepare and cure. Screw piles are quicker to install and cause less disruption to your garden, making them a popular choice for medium-sized rooms. Timber sleeper or beam systems sit between the two, offering a reasonably quick, cost-effective base for lighter structures. Which?'s guidance on building a garden room stresses that a perfectly level foundation is essential, and most suppliers will specify a particular base type before they’ll deliver your cabin.

Installation itself is usually quick once the groundwork is done. The same Which? guidance notes that a sturdy, insulated garden office can take around four to five days on site, while simpler summerhouses are often finished in one to three days depending on complexity and the foundation chosen.

A few things commonly cause delays: poor weather during assembly, restricted site access for delivery vehicles, or a base that wasn’t prepared to the exact specification the supplier requested.

1. Confirm your foundation choice matches the weight and size of your chosen cabin.
2. Prepare the base to the exact level and dimensions your supplier specifies.
3. Check site access is clear for delivery vehicles before your installation date.
4. On handover, check the foundations are level and electrics have been tested.
5. Keep your warranty documents and maintenance advice somewhere you can find them.

How to brief and get the best quote

A clear brief is the single best way to avoid surprises later, and it also makes it much easier to compare quotes from different suppliers on equal terms.

Your brief should include the precise external footprint you’re working with, your intended use, and every service you’ll need: electrics, heating and, if relevant, plumbing. Add your preferred internal finishes and flag any planning constraints you already know about, such as a nearby boundary or an existing outbuilding that counts towards your coverage limit.

When you speak to suppliers, ask the same set of questions each time so the answers are directly comparable:

• What’s the lead time from order to delivery, and does that include manufacturing?
• Are groundworks and foundation preparation included in the quote, or charged separately?
• What guarantee covers the structure, and does it include rot protection?
• Who arranges Building Control sign-off if your room needs it?
• Is VAT included in the price you’ve been given?

Before you sign anything, check the contract itself. It should set out an itemised scope of works, clear payment milestones tied to stages of the build, a defined period for fixing any defects after completion, and full warranty paperwork you can keep on file. A supplier who’s happy to put all of this in writing is generally one worth trusting with a bespoke order.

Practical tips from building bespoke garden rooms

Customers asking for a made to measure build tend to request the same handful of upgrades again and again, and it’s worth knowing why each one matters.

Factory-applied paint finishes come up often, mainly because they save years of maintenance compared with staining or painting on site. Extra glazing is another common request, usually to bring more natural light into a room used as an office or studio through the darker months. Thicker insulated walls are requested by anyone who already knows they’ll be using the room daily through winter, rather than just in summer.

Our bespoke log cabin design process starts with exactly this kind of conversation about use, size and finish, because a room built around your actual habits works far better than one built to a generic template. For readers planning a larger layout, our multi-room log cabins examples show how partitioned spaces can work in practice, and our apex roof cabins range gives a sense of how a traditional pitched roof changes the look and internal headroom of a bespoke build.

• Factory paint finishes cut down on years of future maintenance work.
• Extra glazing brings more natural light into offices and studios.
• Thicker insulated walls suit anyone planning daily, year-round use.
• Multi-room layouts need early planning to avoid wasted floor space on partitions.

Questions to ask before you order

Before you commit to a made to measure garden room, a short list of questions can save you a great deal of hassle later.

Ask what the warranty actually covers, and for how long, since rot protection and structural cover often run for different periods. Ask about delivery: will the supplier confirm a firm date once manufacturing is complete, or only a rough window? Check what after-sales service looks like if something needs adjusting once the room is installed, such as a door that’s settled slightly or a glazing unit that needs attention.

It’s also worth asking whether the price you’ve been quoted is genuinely final, or whether common extras like electrics, groundworks or Building Control fees will be added afterwards. A supplier who answers these questions clearly and in writing, rather than verbally and vaguely, is one you can trust to deliver what you’ve actually ordered.

Payment and deposit terms for bespoke orders

Bespoke builds are made to your specification, so most suppliers ask for payment in stages rather than a single sum upfront.

A typical structure starts with a deposit to confirm your order and begin the design and manufacturing process, followed by a further payment once the cabin is ready for delivery, with a final balance due on completion or handover. This staged approach protects both sides: you’re not paying the full amount before any work has started, and the supplier has confirmed funds before committing materials and labour to a custom design.

Always check what happens if you need to change the specification after placing your deposit, since bespoke orders are harder to amend once manufacturing begins. A clear written payment schedule, tied to specific stages of the build, is one of the clearest signs of a well-run supplier.

From order to completion: what to expect

A bespoke build follows a fairly predictable sequence, even though the exact timing depends on size and specification.

It typically starts with a design discussion, where your brief is turned into a firm specification and drawings for you to approve. Once you’ve signed off the design, the cabin moves into manufacturing, which takes longer for larger or more heavily customised builds than for a simple standard size. Delivery is scheduled once manufacturing is complete, and this is usually coordinated with your foundation work so the base is ready and fully cured by the time the cabin arrives. Installation follows, taking anywhere from one to five days on site depending on the room’s size and complexity, as outlined earlier. A final handover covers checking the finished room, testing electrics and handing over warranty documents.

Knowing this sequence in advance helps you plan around it, particularly the foundation work, since that needs to be finished well before your delivery date rather than rushed at the last minute.

When bespoke is worth the extra cost

Bespoke is worth it when your garden has an awkward shape, when you’ll use the room every day for years, or when insulation and finish matter more to you than the lowest possible price. A standard-size kit rarely fits an irregular plot neatly, and squeezing a generic footprint into an odd-shaped space often wastes the garden area you were trying to make better use of.

A standard kit still makes perfect sense for simpler needs. If you want a straightforward summer house for occasional weekend use, or you’re working to a tight budget, a standard range can deliver good value without the design time a bespoke project needs.

My honest view, after seeing how differently people use these rooms, is that the people who regret going bespoke are rare, but the people who regret settling for a size or layout that doesn’t quite fit are common. If you’re planning daily use for years to come, our bespoke log cabin design route is built exactly for that decision.

— Martin

Getting your own made to measure garden room

We build made to measure garden rooms around your exact footprint, your intended use and the finish you want, rather than asking you to adapt your plans to fit a standard size. Our Bespoke Log Cabin Service covers the full design conversation, and we offer professional installation alongside it if you’d rather leave the groundwork and assembly to experienced hands. Delivery runs across the UK mainland, so wherever your garden is, the same bespoke process applies.

To get started, send us your site dimensions, a few photos of the space and a note on how you plan to use the room. From there, we’ll talk through your design in a bit more detail and put together an itemised quote so you know exactly what’s included before you commit to anything.

• Share your plot dimensions and any boundary constraints you’re aware of.
• Tell us your intended use so we can recommend the right insulation and wall thickness.
• Send a few photos of the space so we can advise on access and foundation options.

If you’d rather browse examples first, our garden offices and contemporary garden buildings ranges show the kind of finishes and layouts we work from when building a bespoke specification. When you’re ready, head to our bespoke build service page to start the conversation.

FAQ

Is it cheaper to buy or build a garden room yourself?

A basic self-assembly kit is usually the cheapest route, with simple uninsulated cabins costing roughly £3,000 to £5,000. Building fully from scratch can work out similarly or more expensive once you account for materials, tools and your own time, so a kit often offers better value unless you already have the skills and equipment.

How much does it cost to have a garden room built?

Costs depend heavily on insulation and size: a simple, uninsulated self-assembly cabin typically runs £3,000 to £5,000, while a properly insulated, double-glazed bespoke room for year-round use usually starts upwards of around £10,000, according to Which?'s cost guidance. Luxury turnkey builds with full services cost more again, depending on specification.

What size garden room can I build without planning permission?

Under permitted development rules, your outbuilding generally can’t exceed a height of 2.5 metres if it sits within 2 metres of a boundary, and all outbuildings together must not cover more than 50% of the land around your original house, according to GOV.UK’s technical guidance. Checking your total garden coverage before finalising a size avoids an unwelcome surprise later.

What is the cheapest way to build a garden room?

A simple, uninsulated self-assembly cabin is the lowest-cost option, typically priced between £3,000 and £5,000 according to Which?. Keeping the footprint under 15 square metres can also help you avoid Building Regulations costs, since buildings below that size are often exempt.

Do I need Building Regulations approval for a garden room?

It depends on size and use: buildings under 15 square metres are often exempt, those between 15 and 30 square metres may be exempt if they meet proximity or material conditions, and anything over 30 square metres or containing sleeping accommodation usually needs full approval, according to Building Regulations guidance. Adding insulation, heating or electrical sockets can bring Building Regulations into play even for a planning-exempt room, so it’s worth checking early.

Sources

• Gov
• How to buy the best garden room - Which?
• Legislation
• Building Regulations for Garden Rooms Explained - PlansMadeEasy

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