If you own a listed building or a scheduled monument, a specific consent is needed if you want to make changes.
Works to scheduled monuments need scheduled monument consent from Cadw on behalf of the Welsh Ministers.
In the case of listed buildings, alterations, which include demolition or extensions, need a listed building consent from the local authority, or from the Welsh Government in the case of local authority buildings. There are call in or appeal powers for the Welsh Ministers. Special arrangements (ecclesiastical exemption) are in place for listed places of worship in the care of one of six exempted denominations.
Properties in conservation areas and within the scope of a World Heritage Site may need consents too — your local authority conservation officer will be able to advise you.