How Much Does a Garden Room Cost?
Updated: 11 hours ago
An insulated garden room typically costs £15,000 to £25,000 at 9 to 12 square metres and £26,000 to £50,000 at 18 to 24 square metres, supplied and fitted including VAT, with a basic timber cabin below that and a bespoke hardwood glass garden room at the top of the market. What sets the price within each tier is the size, how much of it is glazed, the roof, what the room is used for, and the costs that sit outside the building itself: the base, the services run from the house and any approvals.
We design and build hardwood garden rooms that are glazed, insulated and made to order, and the guidance below covers the whole market for comparison.
Typical UK prices
Supplied and fitted, including VAT:
Insulated garden room, 3m x 3m: £15,000 to £20,000.
Insulated garden room, 12 to 15 square metres: £18,000 to £30,000.
Insulated garden room, 18 to 24 square metres: £26,000 to £50,000.
Bespoke, highly glazed garden room: £3,000 to £5,000 per square metre, so a well-specified 12 square metre office is £30,000 to £45,000.
Extras: lighting and power £300 to £800, heating or cooling from £1,000, a WC or shower room £2,000 to £6,000.
Bespoke glazed hardwood rooms like ours sit at the upper end. These are typical UK market prices from published cost guides as of 2026; bespoke designs are priced after a survey.
How much does a garden room cost by type?
An off-the-shelf timber cabin is the entry point. It is delivered as a kit, sits on a simple base and is usually uninsulated or lightly insulated. It suits storage, a summer studio or a hobby space. Prices are low and so is the performance.
A modular insulated garden room is the middle of the market. Factory-made panels, insulated walls and roof, double-glazed doors and a fitted interior. It works as a home office or gym for most of the year. The price rises with size and glazing, and the design is limited to what the system makes.
A bespoke hardwood glass garden room is designed for the site, and our guide to luxury garden rooms shows what that looks like. A durable hardwood frame, large glazed elevations, an insulated roof, a proper foundation and a specification chosen for how the room will be used. We price each one after a design visit, because the site, the glazing and the use set the figure, and the base and services sit on top of the building. If the room will be used every day, it is the one that is still comfortable, and still looks right in the garden, in twenty years. Our hardwood garden rooms page explains what the hardwood route involves.
What is included in the cost of a garden room?
The building is what most prices describe: frame, walls, roof, glazing and doors. On a bespoke room it includes the internal finish; on a modular room it may or may not.
The base is the first thing left out of a headline price. A garden room needs a level, insulated foundation, and on soft ground, a slope or near trees that means more than a few slabs. A concrete slab with insulation, or a screw-pile foundation where the ground is poor, is priced once the ground has been looked at, and it belongs in the budget from the start.
The services are the second. Power for lighting, heating and sockets means an armoured cable from the house and a consumer unit in the room, installed and certified by an electrician. Data for a home office is easy to add at the same time. Water and drainage, for a room with a bathroom or a kitchenette, is a bigger job and depends on the distance to the existing drains.
The finishes are the last. Flooring, decoration, blinds and lighting fittings. On a glazed room, blinds and lighting deserve to be designed rather than added.
What drives the cost of a garden room up?
Size, in the ordinary way, though the base and services are fixed costs that make a small room expensive per square metre.
Glazing more than anything else. A garden room with one glazed wall costs less than one glazed on three sides, and a glazed room needs better insulation elsewhere to stay comfortable. The glass itself matters: solar control coatings, triple glazing and large single panes all add.
The roof. A flat insulated roof is the simplest. A pitched roof, a lantern, or a green roof each add cost and character.
Use. A home office needs power and data. A gym needs a stronger floor and ventilation. A guest room needs a bathroom, which means water and drainage. The use should be settled before the design, because retrofitting services is far more expensive than designing them in.
Access. A garden room built at the bottom of a long, narrow garden costs more to build than one beside the house, because everything is carried by hand.
What do planning and regulations cost for a garden room?
Most garden rooms fall within permitted development as outbuildings, provided they stay within the height and area limits and are not used for sleeping. If an application is needed, a householder planning application in England has a national fee of £528 (from April 2025), with drawings on top; listed building consent has no fee, but the drawings and heritage statement it needs add cost. Our guide to garden room planning permission sets out when it applies.
Building regulations are separate. A garden room under 15 square metres with no sleeping accommodation is usually exempt. Between 15 and 30 square metres it is exempt if it is at least one metre from a boundary or built of substantially non-combustible materials. Above 30 square metres, or with a bathroom or bedroom, building regulations apply, and the application costs from around £300 for a notice to over £1,500 for full plans.
How much does a garden room cost per square metre?
Per-square-metre figures for garden rooms are less useful than they are for extensions, because the fixed costs are a large share of the total. The base, the services run from the house, the doors and the connection to power cost about the same for a 9 square metre room as for a 15 square metre one, so the small room is far more expensive per square metre. A modular room might quote a per-square-metre rate; a bespoke hardwood room is priced as a building on a site.
The more useful way to compare is by what is included at each price. A room that costs less per square metre but excludes the base, the electrics and the internal finish is not cheaper; it is quoted differently. Ask every supplier for a price that covers the same list, from foundation to the last coat of paint, and compare those.
How much does a garden office cost?
An office used every day costs more than a summer studio of the same size because it needs: insulation to walls, floor and roof so it holds a temperature; double glazing at least, with solar control on a south elevation; sockets, a wired data point and lighting that does not reflect in a screen; and heating, usually an electric panel or air-source unit, with ventilation for a room closed up all day. The base and services sit on top of the building.
What size garden room do you need?
Size is the first cost lever, so settle it by use rather than by what fits:
Around 3m x 2.5m: a one-person office or studio with a desk and a chair.
Around 3m x 3m to 4m x 3m: an office with room for a sofa, or a small gym.
Around 5m x 4m: a garden room for entertaining, a larger gym, or a studio with space to work and sit.
Keep it under 15 square metres with no sleeping accommodation and it is usually outside building regulations, which saves an application.
What should a garden room quote include?
Compare quotes against the same list:
The building, with its frame material, insulation and glazing specification.
The base, and who surveys the ground.
The electrical supply from the house, the consumer unit and certification.
Data, water and drainage if needed.
Internal finishes: flooring, decoration, lighting and blinds.
Delivery, access and removal of spoil.
VAT.
Garden room cost questions, answered
How much does a garden room cost in the UK?
Typically £15,000 to £25,000 for an insulated room of 9 to 12 square metres and £26,000 to £50,000 for 18 to 24 square metres, including VAT. A basic timber cabin costs less; a bespoke glazed room runs at £3,000 to £5,000 per square metre. Check whether the base and services are included, and we quote a bespoke room after a design visit.
Does a garden room add value to a house?
A well-built, properly insulated garden room with power adds usable space and is valued as such. A cabin or an uninsulated summerhouse adds little. Buyers value rooms they can use in January.
Does a garden room need foundations?
Yes. A level, insulated base is what keeps the room dry, warm and square. On poor ground a screw-pile or reinforced slab is needed. Slabs on sand are for sheds.
How long does a garden room take to build?
A bespoke hardwood room is made in the workshop and then assembled on the prepared base, and we confirm the lead time from order to completion with the quotation.
Talk to our design team
If you would like to talk to us about your project, we begin with the site and the use, and the design follows from both.
