You will need to have it inspected as extensions are not an exempt structure. You could easily do it under what is called a building notice (no drawings submitted for approval) but you may still want to have some form of drawings to help back up any agreement or contract between you and a contractor.
Louise
UK Property Services
Answered29 May 2013
1
Anonymous user
Hi Charlie49
Building control would be required if you make any structuural alteration or addition to your property, even if planning permission was obtained under permitted development.
Any purchasers solicitor would check for a building control completion certificate if you've had building work done to your property should you ever decided to sell it.
I hope this helps.
Tom
Link Design and Build