If you suspect or know unauthorised works have been carried out to a listed building, including your own, you should contact your local authority as soon as possible.
Os ydych chi'n amau neu'n gwybod bod gwaith anawdurdodedig wedi'i wneud ar adeilad rhestredig, gan gynnwys eich eiddo eich hun, dylech gysylltu â'ch awdurdod lleol cyn gynted â phosibl.