You will need to apply for listed building consent if either of the following cases apply.
You want to demolish a listed building.
You want to alter or extend a listed building in a manner which would affect its character as a building of special architectural or historic interest.
You may also need listed building consent for any works to separate buildings within the grounds of a listed building. Check the position carefully with the council - it is a criminal offence to carry out work which needs listed building consent without obtaining it beforehand.
If your application for listed building consent is refused, granted with conditions or not determined within 8 weeks of it being validated by the council then you have the right to appeal to the Welsh Ministers.