The general rule is to complete all first fix plumbing before any plastering takes place. This is also true for other trades, such as electricians, who will also carry out first fix before the plasterers come in. Once the first fix is finished, all the plastering related work will be completed.
Is Plumbing Work done after Plastering?
All the plumbing should be done before starting the cement plaster, because you don't want to break the plaster and install pipes later.
