The installation package
Separate below-floor work from the visible basement bathroom installation. Ask whether the scope includes investigating the drain route, opening and restoring the slab, and any required pumping equipment. Coordinate overhead services and ventilation with the shower height and enclosure before ordering materials.
Before accepting a proposal
Check that the written proposal names the products, defines the demolition boundary and explains the connection to retained work. Identify any allowance or unresolved selection, and ask who coordinates the relevant trades. Agree how concealed conditions will be documented and how changes require authorization. A broad installation label leaves too much room for different assumptions about what the finished project includes.
What should the proposal say about the slab?
Whether it will be opened, what information supports the proposed pipe route, and who restores it. Unconfirmed buried conditions should be identified as uncertainties rather than concealed inside a fixed description of finish work.
The owner should confirm the proposed service scope and provider availability independently. This guidance does not identify an approved contractor, establish coverage for a specific property or guarantee acceptance of the project.