Garden Room Cost UK (2026): Prices, Sizes & Planning Rules

How much does a garden room cost in 2026?

A garden room is a fully insulated, double-glazed building in your garden with power, lighting and heating, designed to be used all year. That is what separates it from a shed or summerhouse, and why it costs more. Prices depend mainly on size, how it is built (DIY kit, standard modular design or bespoke), the foundation your ground needs and how far the power cable has to run.

The figures below draw on several 2026 surveys. The Garden Room Guide’s October 2026 survey of published prices from 42 UK companies gives a typical £19,700 for a 3m × 3m room, including VAT and installation. Less.co.uk puts a typical insulated garden room at £10,000–£30,000 with an £18,000 average, MyJobQuote gives an average garden office cost of £15,000, and MyBuilder quotes £15,000–£25,000 for a professionally installed modular room. The spread reflects real differences in specification, so compare what is included, not just the headline price.

Garden room cost by size

Size	Floor area	Lower end	Typical	Upper end	Typical per m²
2.5m × 2m	5m²	£12,400	£15,700	£18,500	£3,140
3m × 2.5m	7.5m²	£13,800	£18,600	£25,200	£2,480
3m × 3m	9m²	£14,800	£19,700	£26,400	£2,190
4m × 3m	12m²	£17,500	£22,200	£30,800	£1,850
5m × 3m	15m²	£19,400	£25,500	£35,700	£1,700
6m × 3m	18m²	£21,300	£28,200	£39,300	£1,570
5m × 4m	20m²	£22,200	£29,800	£39,800	£1,490
6m × 4m	24m²	£24,300	£33,600	£43,900	£1,400

Notice how the price per m² falls as the room gets bigger. The Garden Room Guide found prices behave roughly like a fixed £12,400 plus about £900 per m², because design, delivery, doors, windows and electrics cost much the same whatever the size. Going from 3m × 3m to 4m × 3m typically adds only £2,000–£6,000, so size up if your garden and the planning rules allow it.

Garden room cost per m²

Sources measure this differently. The Garden Room Guide’s standard rooms work out at £1,400–£3,000 per m², bespoke rooms at £2,000 to over £3,000 per m². MyBuilder quotes £1,200–£2,500 per m² for professionally built rooms, and Less.co.uk a lower £800–£2,000 per m². MyBuilder warns that headline per-m² prices can exclude foundations, VAT and internal finishes, which can add £5,000–£15,000. For comparison, a single storey extension costs £1,800–£3,500 per m² before VAT, plus fees.

Garden room prices by type

Type	Typical price	What is usually included
Self-build log cabin kit (3m × 3m)	£3,600 – £5,400	Kit only; no base, electrics or insulation lining
Insulated panel or flat-pack kit (3m × 3m)	£5,000 – £13,000	Insulated panels; base, assembly and electrics extra
Garden office pod	£3,500 – £7,000	Small prefabricated unit for one desk
Standard modular garden room, installed	£15,000 – £30,000	Insulated, glazed, internal wiring, flooring, often a base
Bespoke garden room	£25,000 – £40,000+	Designed for the site, premium cladding and glazing
Brick-built garden room	£15,000 – £40,000+	Built on site like a mini extension
Garden studio with shower room	£30,000 – £60,000+	Plumbing, drainage and hot water included

DIY kit vs professionally installed

A self-build kit is the cheapest route, but the price rarely includes the base, electrics, insulation lining or decoration, and log cabin kits are not insulated to the standard you need for year-round office use. Less.co.uk estimates a kit saves £3,000–£8,000 against a fully installed room. Remember that the electrical connection must be installed and certified by a qualified electrician under Part P whichever route you choose.

Garden office cost

A garden office is the most common use for a garden room. For one person, a 3m × 3m or 3m × 2.5m room is usually enough; two desks or a meeting space need 4m × 3m or more. MyJobQuote puts small, fully insulated timber garden offices with electrics at £9,000–£15,000, medium at £12,000–£20,000 and large at £18,000–£30,000. Budget extra for a reliable internet connection: running an ethernet cable or mesh link costs around £100–£300 (Less.co.uk), and air conditioning £1,500–£3,000 if the room faces south.

Cladding choice moves the price too. MyJobQuote’s 2026 data puts a typical garden office at £11,500–£14,500 in exterior-grade board, £12,000–£15,000 in treated softwood and £15,000–£19,000 in cedar.

Foundations: ground screws vs concrete

A garden room needs a level, solid base. The main options are:

• Ground screws: steel screws driven into the ground in a few hours. The Garden Room Guide puts ground screws or a fitted base at roughly £1,000–£2,500 for a 3m × 3m to 4m × 3m room. They suit sloping gardens, cause little mess and avoid digging near tree roots.
• Concrete slab: MyBuilder quotes £80–£120 per m², but the Garden Room Guide found full concrete bases priced at £3,000–£6,500 once excavation, waste removal and reinforcement are included, more on slopes or poor ground.
• Timber frame on concrete pads: a cheaper option for lighter buildings on firm, level ground.

Prices vary because ground conditions vary, so most companies only price the base after a site survey. The Garden Room Guide found that 11 of the 20 companies it checked in detail included a base in their price.

Electrics, insulation and heating

Electrical connection

Internal wiring (lights and sockets to a consumer unit in the room) is almost always included, but the connection to the house usually is not: only 3 of 20 companies in the Garden Room Guide’s survey included it. Allow about £1,500–£3,500 for a typical 10–20m armoured cable run, according to the Garden Room Guide. Less.co.uk and MyBuilder quote lower figures of £500–£1,500 and £800–£1,500 for a basic supply. The cost depends on the distance, whether the cable is trenched or clipped, and whether your house consumer unit needs upgrading.

Insulation

For year-round use, Less.co.uk recommends 50–100mm of rigid PIR or phenolic insulation in the walls and at least 100mm in the roof; 25mm or less is not enough. Insulation materials are relatively cheap (about £500–£1,500 for a whole room, according to MyBuilder), so this is not the place to cut corners on an insulated garden room.

Heating and cooling

Electric panel heaters cost around £200–£500 for two or three units and an infrared panel £100–£400 (Less.co.uk). Underfloor heating costs £500–£1,500 (MyBuilder).

Adding a toilet or shower room

Plumbing is the biggest single upgrade. Less.co.uk puts a WC at £1,500–£2,500 and a full shower room at £2,500–£3,500; MyBuilder gives a total of £3,000–£8,000 including drainage, which alone can cost £1,500–£3,000. The distance to your drains and the fall of the ground make the biggest difference, so get a site visit before committing. New drainage also needs building regulations approval.

Garden room prices by region

Region	Typical 12m² insulated garden office, fully installed	vs national
London	£22,000	+25%
South East	£20,000	+14%
South West & East of England	£18,000 – £19,000	+3% to +8%
Midlands	£17,500	average
North of England & Wales	£15,000 – £16,500	−6% to −14%
Scotland & Northern Ireland	about £16,000	about −9%

Full garden room cost breakdown

Cost item	Typical cost	Notes
Garden room supply and installation	£15,000 – £30,000	Standard insulated room, 9–20m²
Foundations	£1,000 – £6,500	Ground screws at the low end, concrete slab at the high end
Electrical connection to the house	£800 – £3,500	Depends on cable length and consumer unit
Heating	£200 – £1,500	Panel heaters to underfloor heating
Internet or data cabling	£100 – £300	Rarely included
WC or shower room (optional)	£1,500 – £8,000	Drainage distance is key
Landscaping and path	£500 – £2,000	Often forgotten
Blinds and fit-out	£400 – £1,900	Blinds, shelving, desk
Lawful development certificate (optional)	£274	England, from 1 April 2026
Householder planning application (if needed)	£548	England, from 1 April 2026
Building control (if needed)	£600 – £1,200	Larger rooms near a boundary, sleeping use, or new drainage
Contingency	10%	Ground conditions and extras

Garden room planning permission

Most garden rooms in England are built as outbuildings under permitted development (Class E), so they do not need planning permission. According to the Planning Portal, the main conditions are:

• Not forward of the principal elevation: no outbuilding in front of the main front wall of the house.
• Single storey, with eaves no higher than 2.5m.
• Maximum height of 4m with a dual-pitched roof or 3m with any other roof (including the flat roofs most garden rooms have).
• No more than 2.5m high if within 2m of a boundary. This is the rule that catches most garden rooms, so many are designed to be just under 2.5m tall.
• Outbuildings and extensions together must not cover more than 50% of the land around the original house.
• No verandas, balconies or raised platforms over 0.3m high.
• The use must be incidental to the house: not separate self-contained living accommodation and not a bedroom.

Extra limits apply on designated land. In National Parks, the Broads, National Landscapes (AONBs) and World Heritage Sites, outbuildings more than 20m from the house are limited to 10m², and in these areas and conservation areas, an outbuilding at the side of the house needs permission. Any outbuilding within the curtilage of a listed building needs permission, and flats and maisonettes have no permitted development rights. Which? also notes that a garden office with regular client visits may need planning permission because it is no longer incidental to the home. If in doubt, a lawful development certificate (£274) gives you proof the room is lawful. Our extension planning permission guide explains how permitted development works in more detail.

Do garden rooms need building regulations?

Detached outbuildings are often exempt from building regulations. Based on the exemptions summarised by St Albans City and District Council and Which?:

• Under 15m² internal floor area: normally exempt, provided there is no sleeping accommodation.
• 15–30m²: normally exempt if there is no sleeping accommodation and the building is either at least 1m from any boundary or built substantially of non-combustible materials.
• Over 30m², or any room used for sleeping: full building regulations approval is needed.

Even an exempt garden room still needs its electrics certified under Part P, and any new drainage for a WC or shower needs building regulations approval. Keep all certificates, because a buyer’s solicitor will ask for them.

How long does a garden room take?

1. Survey, design and quote: 1–3 weeks
2. Lead time: popular companies can be booked several weeks or months ahead in spring and summer
3. Lawful development certificate (optional): up to 8 weeks
4. On site: MyJobQuote estimates about 2 days for a small or medium modular build and 7–10 days for a large one; bespoke and brick-built rooms take longer

How to save money on a garden room

• Compare like for like. Check whether the base, electrical connection, flooring, heating and VAT are included; the Garden Room Guide found most companies do not include the house connection.
• Keep the cable run short by siting the room closer to the house, where the garden allows.
• Choose standard sizes and cladding. Changing cladding moves the price by only around 3%, but bespoke shapes add much more.
• Buy outside the spring and summer peak, when many companies offer better prices.
• Stay within permitted development and under the building regulations thresholds to avoid fees and delays.
• Consider a kit only if you are handy, and still use a qualified electrician for the connection.

Does a garden room add value?

Possibly, but there is no reliable official figure. The most quoted estimate, from estate agent Barrows and Forrester in 2023, suggested a garden office could add around 7.5%, but the Garden Room Guide points out this is one agent’s estimate rather than a measure of sale prices. Rightmove has reported that far more listings mention garden offices than a decade ago, so they are a selling point. A garden room does not add a bedroom, though, so if adding value is the main goal, a loft conversion or a garage conversion usually delivers more.

Frequently asked questions

How much does a 3m × 3m garden room cost?

A fully insulated 3m × 3m garden room typically costs £14,800–£26,400 installed, with a typical price of about £19,700 including VAT (The Garden Room Guide, October 2026). An insulated self-build kit of the same size costs around £8,800–£13,000 before the base, assembly and electrics.

Do I need planning permission for a garden room?

Usually not, if it meets the permitted development rules for outbuildings: single storey, not in front of the house, no more than 2.5m high within 2m of a boundary, and no more than half the garden covered. Listed buildings, flats and some designated areas need permission.

Can I sleep in a garden room?

Not under permitted development. Outbuildings must be incidental to the house and cannot be used as a bedroom or self-contained accommodation without planning permission, and sleeping use also brings the building under full building regulations.

Is a garden room cheaper than an extension?

Yes, per project. A 12m² garden office typically costs £17,500–£30,800 installed, while our calculator puts a 16m² standard single storey extension at £44,500–£59,000 all-in in the Midlands. An extension, however, adds space to the house itself and usually more value.

How much does it cost to run electricity to a garden room?

Typically £800–£3,500, depending on the distance from the house, whether the cable is buried and whether your consumer unit needs upgrading. The Garden Room Guide suggests allowing £1,500–£3,500 for a 10–20m run.

Are ground screws better than a concrete base?

For most lightweight timber garden rooms, ground screws are quicker, cleaner and work well on slopes or near tree roots. Concrete slabs suit heavier or brick-built rooms. Your supplier should recommend the right base after a site survey.

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