my bulder has built a new two floor extension, with 2 internal doors to the main house. . The B.I inspector says they should be fire doors, with 30 minute fire resistance. The builder says fire doors are only needed to garages and similar sites, and anyway the building is a listed building and all the other doors are not fire doors and do not need to be changed. He also says that all he did was replace two existing doors with two new ones. Who is right?