It also includes where more or fewer dwellings are created within an existing building, such as where a house is converted to multiple flats or a block of flats converted to a single house.
Mae hefyd yn cynnwys lle mae mwy neu lai o anheddau’n cael eu creu mewn adeilad presennol, fel lle mae tŷ’n cael ei droi’n fwy nag un fflat neu floc o fflatiau wedi’i droi’n dŷ sengl.