The boom in garden rooms since 2020 has produced a huge market of products ranging from well-insulated, properly constructed timber studios to essentially glorified sheds at premium prices. Understanding what you're actually getting — and whether it serves your needs better than a conventional house extension — is the first decision to make.
Key Differences
A house extension is connected to the main dwelling, adds to the legal floor area of the property, forms part of the building for EPC and council tax purposes, and requires planning permission (or permitted development compliance) and building regulations approval. It has structural foundations, connecting floors, and integrated services. It can accommodate any use — including sleeping or living.
A garden room is a separate structure in the garden. Properly constructed, it can be year-round usable. But it involves crossing the garden to reach it (in the rain, at night, in winter), it cannot have sleeping accommodation without becoming a separate dwelling requiring planning permission, and it adds less value to the property than an equivalent floor area added to the house itself.
When a Garden Room Makes Sense
A garden room is the right choice when: you need a dedicated space for work, exercise, or hobbies that benefits from separation from the house; your permitted development rights allow it without planning permission; you need the space quickly (garden rooms are typically installed in 1–2 weeks); and you don't want the disruption of a conventional build.
It's the wrong choice when: you need to add living space connected to the house (a kitchen, a bedroom, a dining room); you want to maximise property value; or your garden is already small and a structure will further reduce usable outdoor space.
Quality Differences
The quality range in garden rooms is extreme. A well-specified garden room has: engineered timber frame, 90–100mm insulated walls (PIR or mineral wool), double-glazed thermally broken windows and doors, breathable membrane, proper ventilation, and tanked or DPC-protected floor. A poorly specified one has: thin single-skin timber panels, single-glazed units, no thermal break, and is cold in winter despite the heating running constantly.
Always ask suppliers for their wall, floor and roof U-values. A good garden room should achieve around 0.18–0.22 W/m²K for walls — comparable to building regulations requirements for extensions.
Costs Compared
| Option | Cost per m² | Lead time |
|---|---|---|
| Quality garden room | £1,500–£3,500/m² | 6–12 weeks |
| Single-storey extension | £2,000–£3,500/m² | 6–12 months |
| Double-storey extension | £1,500–£2,500/m² | 9–18 months |