Garden Annexes
A self-contained home in your garden: bedroom, bathroom, kitchen and living space, built for a parent, adult child or future care needs. We explain the planning rules, realistic costs and what separates a proper annexe from a glorified shed, then connect you with suppliers who can deliver it.
Is this the right service for you?
This route suits families with a reasonable garden (most annexes need at least 40-50 sqm of plot) who want maximum independence for the relative moving in: their own front door, their own space, and privacy for everyone. If your garden is small or access is tight, a garage conversion or extension may work better.
What's Included
Planning route mapped first
Self-contained garden accommodation usually needs planning permission, and the ancillary-use condition matters. We explain the routes, householder application or lawful development certificate, before you commit money.
Full building regulations compliance
Any building someone sleeps in must meet building regs: structure, insulation, fire safety, drainage, electrics. We show you what a compliant specification looks like so you can compare quotes properly.
Realistic cost expectations
Garden annexes run roughly £20,000-£70,000 for modular builds and £60,000-£160,000+ for brick, before groundworks and services. We break down what drives the price.
Design for later life
Level thresholds, wider doorways, walk-in showers and future-proofed layouts cost little extra at build time and everything to retrofit.
Matched supplier quotes
Tell us about your garden, budget and timescale, and we will point you at annexe suppliers suited to your project so you can compare like-for-like quotes.
What separates an annexe from a garden room
The industry blurs the line deliberately: plenty of 'garden rooms with a shower' are sold as annexes. The legal difference is use. A building where someone lives, sleeps, cooks and washes is a dwelling in planning terms and must meet full building regulations. A garden office does not.
That difference drives everything: foundations, insulation levels, fire safety, drainage connections and, crucially, planning. Buying a garden-room specification for a relative to live in risks enforcement action and a building that is cold, non-compliant and unsellable.
A properly consented, building-regs-signed-off annexe is a genuine asset: family accommodation now, home office or guest space later, and documented compliance when you sell.
Common Questions
How big can a garden annexe be?
Practically, most single-storey annexes are 25-60 sqm. Planning, not permitted development, governs a residential annexe, so the limit is what your council will approve for your plot: garden coverage, neighbour impact and access all count. A studio annexe works from around 25 sqm; a comfortable one-bed needs 35-45 sqm.
How long does a garden annexe take?
Planning typically takes 8-10 weeks from a validated application. Modular annexes are then manufactured in 6-12 weeks and installed in days once the base is ready. Brick builds take 3-5 months on site. End to end, allow 5-9 months from first enquiry to moving in.
Do I need separate utilities for an annexe?
Most annexes share the main house supplies, with sub-metering if you want to track usage. Fully separate connections are possible but expensive and can strengthen the case for separate council tax banding. Drainage is usually the constraint that shapes the design, so get it assessed early.
Discuss Your Project
Tell us about your project and we'll point you at the right route and suppliers worth talking to. No pressure, no obligation.
Get Annexe Quotes