For a side extension to a detached Property in Essex. A builder measured it to be about 8m long and 2.7m wide. .

You will need to contact your local planning department, to see what they allow, but you will need buildings regs.

no you dont need planning for this extension , but you will need build regs. the build inspector still as to come out and pass the project at diffrent stages , hope this is helpfull to you . paul

Yes you will need planning permission.

Ground floor extensions not exceeding between 50m3 and 70m3, depending on local rules, no higher than 4m do not need planning permission. But they must be within the permitted development area of a property's original boundaries, which means any previous extensions should be taken into account. So as long as the house has no previous extensions and it is single story and for arguments sake say 3m high then yes you probably would be allowed to build with building regs only as total build would be in the region of 64m3. Work out exact m3 and pop down to planners, as local rules apply.