Size and scope

A half bath, a hall bath and a primary bath are different jobs. Most of the cost is labor, so more surface means more time.

Moving plumbing

Keeping the toilet, tub and sink where they are saves the most. Moving a drain in a slab home means cutting concrete.

Tile and pattern

Small tiles and patterns like herringbone take longer to lay than large plain tiles.

Glass

A frameless glass door is one of the bigger single items. A fixed panel or a curtain costs far less.

What is behind the walls

Old leaks, rotten framing or outdated wiring show up once the walls open. Ask how surprises are priced.