Tub-to-shower conversion is the specific version of a shower conversion where the original alcove tub comes out and a tiled walk-in goes into the same footprint. Berkeley is full of candidates: 1905 to 1930 Craftsman and brown-shingle homes where the original cast-iron tub is still sitting on wood framing that has flexed under it for a century, and postwar homes in the flats with steel tubs nobody has bathed in for years. Cost typically lands at $16,000 to $28,000 for a straight swap with mid-grade tile and a standard glass panel. Timeline runs 3 to 4 weeks. The recurring Berkeley surprise is what lives under the old tub, soft subfloor, corroded galvanized branches, sometimes the original lead drain bend, and a good quote anticipates that rather than change-ordering it mid-build.