Who is responsible for supervision and quality control?
Your contractor and you are both responsible for ensuring that the work is carried out to acceptable standards and in accordance with the approved plans and contract documentation. Your contractor is responsible for ensuring that any work carried out by sub-contractors is to an acceptable standard.

Regular contact and discussions should happen between you and your contractor as this allows for problems to be discussed and addressed as, and if, they arise.

It may be worth considering using a private building consultant or inspector to inspect the works and raise any issues with your contractor.

Certifiers are required to act in the public interest in regard to health and safety but can not undertake a supervisory role or report on the quality of work on your behalf.

Additional information is available in BSA's Facts for Smart Building and Renovating