For a projected to be completed and/or completion certificate to be issued LABC or Approved Inspectors have to be reasonable satisfied that all the work complies with the requirements, unfortunately they are not project managers, nor have the resources to check projects everyday. So have to take...
Building Control would ensure the same standard to any habitable room in the roof whether it is called a bedroom or an office. Was your house built on land previously used as employment land?? There is a development local to me where houses were built on land that previously housed a factory so...
It sounds like you need to employ a project manager to oversee the project on your behalf. Building control officers (whether LABC or Approved Inspectors) are there to ensure the building regs are complied with. If you want a service over and above that then employ the appropriate professional. 8)
Yes it is controllable work and constitutes building work which is not covered by any competent persons scheme. An application will be required. Schemes such as FENSA will only cover replacement windows where size of openings remain the same (both height and width). Speak with your local LABC...
If you are carrying out a simple kitchen refit then your work is probably not controllable under the BRs therefore any mechanical extract would be up to you what standard you choose.