If your flat is a listed building it is likely you will need listed building consent and you should contact your local planning authority for advice before you start work.
Os yw’ch fflat yn adeilad rhestredig, mae’n debygol y bydd angen caniatâd adeilad rhestredig arnoch, a dylech gysylltu â’ch Awdurdod Cynllunio Lleol i ofyn am gyngor cyn dechrau ar y gwaith.