Have you built a garden annexe, if so how much was it?

[Fressia123]

We'll probably need to build one in our patio as it's the only we can potentially add a fourth bedroom. I know they have to comply with building regulations but haven't been able to find any pricing. Tia.

We recently finished building ours, it's a large 6m square room with double height ceiling and mezzanine office with bathroom and walk in storage, with added workshop, laundry and garden store. All in all it cost around £150k, although we could have done it more cheaply, eg we wanted it to be oak framed and oak clad.