Bathroom remodeling in Oregon has to respect a house that may never fully dry out west of the Cascades. A valley bungalow bath, a coast bath, and a drier east-side bath are not one showroom. The fan has to leave the building. Plenty of older ducts end in a crawl or an attic, and that is how the shower becomes wood rot. Find the end of the duct before you choose tile or a surround.
A window in the shower wall is a classic wet-side leak, and rain on that opening for months is not a caulk problem. Ask what goes behind the new walls and whether the alcove is square. Moving a toilet over a crawl means joists you can actually see and a drain that may already sag. A prefabricated base and a tiled shower fail in different places.
Layout changes are harder when the stack drops through a tight crawl or a plaster wall nobody wants to open twice. Say if access is from below. Adhesives and waterproofing want a house that is dry enough to cure. Do not open an exterior wall into a week of rain. Grab bars need blocking if this is the only bath. A curbless opening may mean cutting the floor.
Sort roof leaks from bath leaks before you bury either one. On a wet-side house they meet in the same wall and then both get blamed on the fixture. Keep the waterproofing specific: a sheet, a liquid, or a prefabricated base, and how the floor slopes to the drain. A pretty fixture on a flat floor is a pond. East of the mountains the air is drier and the fan still has to exit, because the shower does not care about the desert.
Say the town, tub or shower, and whether the layout stays. Mention a fan that dies in the attic, a shower window, or a crawl that already smells wet. You do not need a drawing. You need the room and whether the wood behind it is still sound. Call the number on this page.