Electrics every conversion needs
- —A new circuit from the consumer unit, sized and certified separately from the existing garage supply if one exists.
- —Double sockets at a density suited to the use — more for an office or gym than a playroom.
- —Lighting on its own switched circuit, with additional circuits for task lighting in an office or gym.
- —Smoke detection linked to the house system where required by the building warrant.
- —An RCD-protected circuit for any electric underfloor heating or outdoor-adjacent sockets.
When plumbing is needed
A home office, gym, playroom or cinema needs no plumbing at all. Plumbing becomes necessary the moment the room includes a kitchenette, a shower room, or a utility function such as a washing machine — each of those needs a water supply and a drainage connection.
Drainage and the soil stack
Connecting a new shower room or kitchenette to the existing drainage depends on how close the garage sits to the house's soil stack. A short run keeps cost down; a long run, or one that needs to go uphill, requires a pumped connection called a macerator system, which adds £700 to £1,400 to the job.
Consumer unit capacity
An older consumer unit may not have spare capacity for the new circuits a conversion needs. Where it doesn't, the unit is upgraded as part of the job — this costs £450 to £900 and is confirmed at survey, not discovered mid-build.
What gets certified, and by whom
Electrical work is certified by a registered electrician independently of the building warrant's own inspection stages, and the certificate is handed over at completion alongside the warrant's completion certificate. Keep both documents together — a solicitor will ask for them at any future sale.