Most garage conversion advice talks about square footage and finishes, as if a garage is a garage. It isn't. Whether yours is integral, attached, or fully detached from the house changes almost every practical decision that follows — often before you've thought about what you actually want the room to become.
The three types, in plain terms
- Integral garage — built into the footprint of the house itself, sharing walls, roof and foundations with the rest of the building. The simplest and usually cheapest to convert.
- Attached garage — joined to the house by a shared wall or a short connecting structure, but not fully absorbed into the house's original footprint.
- Detached garage — a separate structure entirely, often further from the house, sometimes with its own access from the road.
Integral and attached: the easier route
Because an integral garage already shares structure with the house, you're rarely starting from scratch. The roof, walls and foundations are typically already built to (or close to) house standard, which means less structural work and a faster project. In most cases, using the internal space of an existing integral or attached garage as part of the main house doesn't in itself count as a formal change of use requiring planning permission — though as we cover in our planning FAQs, it's still always worth a written check before work starts.
The trade-off is proximity to the rest of the house. In most homes there's already an opening between the garage and the living space, so no new structural opening is needed at all. Where one is required, a concrete lintel is normally enough — a structural engineer and steel beam only tend to come into play for a genuinely large span, which is the exception rather than the rule.
Detached: more freedom, more to build
A detached garage gives you a genuinely separate space — useful if you're thinking about a home office you can properly leave at the end of the day, a gym, or eventually a small annex. But because it's not sharing structure with the house, more of the fabric of the building needs upgrading to habitable-room standard: insulation, damp-proofing, and often a completely new electrical supply run from the house.
Detached garages also tend to sit further from mains services, so if you're picturing plumbing — a kitchenette, a shower room — the run of pipework and drainage can add meaningfully to both cost and complexity compared with an integral garage a few metres from an existing bathroom.
The practical upside of detached
You can usually keep living in the house completely undisturbed while a detached garage conversion is underway — no dust sheets through the hallway, no noise through a shared wall. For a project you want to run in the background of normal life, that's worth factoring in.
How this changes your regulatory picture
Both routes still need Building Regulations approval for insulation, damp-proofing, electrics and fire safety — that doesn't change based on garage type. What can change is planning permission: detached structures, structures near a boundary, and anything in a Conservation Area or affecting a Registered Building face different (usually tighter) rules than a straightforward integral conversion. Our full planning permission guide goes through this in more depth.
How this changes your cost
As a rough rule: integral and attached conversions tend to sit toward the lower end of typical cost ranges, because less new structure is needed. Detached conversions — especially anything involving plumbing — sit toward the higher end, for the reasons above. Our costs guide breaks this down further, but the short version is that "detached" and "plumbing" are the two words most likely to move your budget upward.
The garage type isn't a detail to mention to your builder — it's the first thing that shapes what your conversion can realistically become.
So which is right for you?
| You want… | Best suited to |
|---|---|
| The cheapest, fastest conversion | Integral or attached |
| A space that feels separate from the house | Detached |
| Minimal disruption while you're still living there | Detached |
| A room with plumbing, close to existing services | Integral or attached |
| A future self-contained annex | Detached (usually, though check planning status) |
This guide is general context, not a site-specific assessment. Every property is different — the fastest way to know what applies to yours is to have it looked at directly.