Put the decision into the scope
Treat a built-in bench as part of the shower assembly, including support, waterproofing, surface drainage and finish joints. Coordinate its dimensions with the base, enclosure and control locations. The installer should detail corners and penetrations rather than treating the bench as furniture added to a completed shower.
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.
Why decide bench dimensions before installation?
They affect usable floor space, wall detailing and water-management junctions. Changes after waterproofing can disturb the assembly and may require more than simply adjusting the finish material.
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.