Yes. Any competent DIYer can install a ShowerDec wetroom floor former. ShowerDec can rest on top of the floor joists, you just need to ensure it is fully supported around the 4 edges. ShowerDecs offset waste outlet is positioned to avoid clashing with joists. Once installed on top of the joists the remaining floor will need to be boarded over to bring it level with the ShowerDec and create a true walk in shower.