If a structural change is made (dormer, roof window, new roof structure, etc.) the owner generally requires a permit from the authorities. If the renovation involves a conversion or extension, documents must be obtained for the building permit. However, there are generally also a few exceptions to this rule when a project can be carried out without requiring a building permit or a building application or declaration. However, to avoid violating the law, it is advisable to contact your local building authorities before commencing your roof renovation.