Is it permissible to build a mortuary washroom for the deceased within mosques, or is it better to wash them in their homes?

Building a washing facility for the deceased inside a mosque is impermissible, due to the necessity of safeguarding the mosque from impurities. However, building it outside, near the mosque, is permissible. There is no special virtue in doing so. The requirement for a place where the deceased is washed is that it be concealed, like a house or a tent.