It covers the new dwellings started (where building work has commenced) as well as new dwellings completed (where building work has finished and the dwelling is ready for occupation).
Mae hyn yn berthnasol i’r Cynlluniau Rheoli Basnau Afonydd a gyflwynwyd i’w cymeradwyo’n wreiddiol, yn ogystal ag unrhyw fersiynau diwygiedig a ailgyflwynwyd.)