Garden annexes 25 to 35sqm
Between 25 and 35sqm, a garden annexe has room for a full kitchen and a proper sitting area, and towards the top of the range a separate bedroom. It is the size at which most people choose between a studio and a one-bedroom layout.
Illustrated from a scale model by The Garden Room & Annexe Guide.
In short
- Layout: a studio with a full kitchen from around 25–30sqm, or a compact one-bedroom annexe from around 30sqm.
- Shape: most are 6–9m long and 3.5–5m deep. A 6m × 4.8m building gives 28.8sqm.
- Cost: a compact one-bedroom annexe of 25–35sqm is typically advertised at £70,000–£85,000 for the building, and £85,000–£105,000 all-in.
- Planning: a self-contained annexe needs full planning permission with Building Regulations, or the Caravan Act route, built to BS3632 with a Lawful Development Certificate. See planning and the Caravan Act route.
Studio or one bedroom at 25 to 35sqm?
This is the range where a bedroom wall becomes possible. Below about 30sqm a separate bedroom tends to leave both rooms cramped; above it, a wall with a pocket door still leaves a comfortable living area.
- Studio with a full kitchen · 25–31 sqm
- One room for living, cooking and sleeping, with a full kitchen rather than a kitchenette. Garden Annexes’ 29.4sqm Ivyo 540 zones the room under a vaulted ceiling, and the owner of Garden Annexes’ 30.9sqm Annexxa 635 chose a sofa bed so the whole room is living space by day.
- Compact one-bedroom · from around 30 sqm
- A separate bedroom, a shower room and a kitchen-living area. Swift Unlimited’s 31.5sqm annexe in Dorset was designed for an autistic adult, and Ark Design Build’s 30sqm one-bedroom annexe uses an angled wall to fit an awkward garden.
- Multi-use · 30–35 sqm
- Some annexes at this size are used as an office or gym by day and guest accommodation at night, such as A Room in the Garden’s 34sqm office, gym and guest bedroom annexe.
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Annexes of 25 to 35sqm built by UK companies
Every annexe of 25 to 35sqm featured on The Guide, in a random order. Each one links to the full write-up, with the floor plan and the company that built it.
Garden Annexe in Scotland
JML Garden Rooms built this 33sqm annexe in Scotland, providing independent living for a family’s mother. Featuring off-site SIPs construction, quick installation, and a modern design, the light-filled home includes a vaulted living room, kitchen, bedroom, and shower room.
1-Bed Annexe for an Awkward-Shaped Garden
Ark Design Build created a 30sqm one-bedroom garden annexe featuring an angled wall to maximise an irregular garden space. The design includes a kitchen, living area, ensuite bedroom, and strategically placed sliding doors, offering modern, light-filled accommodation.
Replace a Garage with a Holiday Let
A garden annexe can generate rental income with proper permissions. Miniature Manors transformed the site of an old garage into a stylish, self-contained holiday let with a double bed, kitchen, shower room, and decked terrace. Required Planning Permission & Building Control.
29.4sqm Open-Plan Ivyo by Garden Annexes
This 29.4 sqm open-plan Ivyo 540 by Garden Annexes is finished in Midnight Black with a vaulted ceiling, exposed trusses and zoned living, kitchen and bedroom space. En-suite shower room and a full turnkey handover, including groundworks and services.
5 Sided Garden Annexe
Executive Garden Rooms designed a unique five-sided garden annexe with no 90-degree corners, maximising space and functionality. This 30sqm, self-contained home features an open-plan layout and pressurised water system. Supplied on a turnkey basis including planning services and groundworks.
31.5sqm One Bedroom Annexe in the Garden
Swift Unlimited designed this 31.5sqm one-bedroom garden annexe in Dorset for an autistic adult, ensuring privacy and independence while keeping family support nearby. Featuring Douglas Fir cladding, large sliding doors, a stylish kitchenette, and an en-suite shower room, it’s a bespoke, low-maintenance home.
Garden Office, Gym and Guest Bedroom Annexe by A Room in the Garden
This annexe by A Room in the Garden delivers a home office, gym and self-contained guest accommodation in one garden building — giving a busy family the space they need and genuine privacy for everyone on the property.
The Bothy by JML Garden Rooms: A Pitched-Roof Garden Room and Annexe
In a market of flat-roofed garden rooms, JML Garden Rooms’ Bothy stands out. This bespoke 31sqm pitched-roof annexe on Loch Fyne uses its height for a mezzanine office above a ground-floor games room, kitchenette and shower room — built to withstand an exposed Argyll lochside.
Frequently asked questions
- Is 30sqm big enough for a one-bedroom annexe?
- Yes, just. From around 30sqm a separate bedroom, a shower room and a kitchen-living area will fit, although the rooms are compact. Below that, most designers keep the layout open-plan so the space is not split into two small rooms.
- Should a 25–35sqm annexe be a studio or one bedroom?
- It depends on who lives there. A studio feels larger than its size and suits one person. A separate bedroom matters more for a couple who keep different hours, or for a carer staying over.
- How much does a 30sqm annexe cost?
- A compact one-bedroom annexe of 25–35sqm is typically advertised at £70,000–£85,000 for the building, with a realistic all-in budget of £85,000–£105,000 once any groundworks and connections not in the price are added. Whether VAT is included depends on the planning route.
Find annexe specialists that cover your area
The Garden Room & Annexe Directory lists UK annexe specialists, filtered by location, planning route and design approach.
Last updated October 2026 · Part of our garden annexe guide.
