15. Where an application is made to a building control authority for a fire safety certificate, the authority, in considering such application, shall—

( a) be restricted to considering only the extent to which the design of the building or works complies with the requirements of Part B of the Second Schedule to the Building Regulations, and

( b) have due regard to any dispensation or relaxation in respect of, or which is relevant to, the works or building to which the application relates.