Boise, Idaho

Tub-to-Shower Conversion — Boise North End

A 1920s North End bathroom where the original cast-iron tub came out and a low-curb tiled shower went in, inside the same 60-inch alcove and the same tight floor plan.

Finished tub-to-shower conversion in a 1920s Boise North End bathroom with white subway tile, hex mosaic shower floor and a glass door — Boise North End conversion — the original 60-inch tub alcove rebuilt as a low-curb tiled shower with period-appropriate finishes. Representative photography of the work described — being replaced with job-site photos from this project.

Project data

Location: Boise, Idaho — North End (Ada County)
Project type: Tub-to-shower conversion
Approximate wet area: 60 x 32 inch alcove
Duration on site: Roughly two and a half weeks
Tile: 3x6 ceramic subway walls, hex mosaic floor
Waterproofing: Liquid-applied membrane over cement board, pre-sloped pan

Existing condition

An original cast-iron tub with a 1990s tub surround glued over the old plaster and tile. Water had been getting behind the surround at the valve for years; the wall framing at the corner was soft and the subfloor at the tub apron had gone spongy. The drain stub was galvanized.

What the homeowners wanted

The homeowners wanted a walk-in shower they could actually use daily, in period-appropriate finishes, without giving up the tiny amount of floor space the bathroom has.

Scope of work

Remove the cast-iron tub in sections, plus the surround and old wall substrate
Replace soft framing at the valve wall and the subfloor section at the apron
Replace the galvanized drain stub while the floor was open
New pressure-balancing mixing valve
Pre-sloped pan with liquid-applied membrane and a low tiled curb
Subway tile walls with a recessed niche in a stud bay
Hex mosaic shower floor for grip and slope tolerance

The problem we hit

Nothing in a 1920s bathroom is plumb, square or level, and the alcove was out of square by close to an inch corner to corner. Running a rigid stacked tile layout would have exposed every bit of it.

How it was solved

We shimmed and re-planed the substrate to get the walls close, then laid out the subway tile from the most visible corner outward so the taper landed at the back inside corner where the eye never goes. The niche was placed in an existing stud bay rather than cutting one, which kept the framing intact in a wall that has already been modified twice in a century.

Materials and systems

Waterproofing: Liquid-applied membrane, reinforced fabric at seams and corners
Pan: Pre-sloped pan with bonded drain flange
Wall tile: 3x6 ceramic subway with dark grout
Floor tile: Hexagon porcelain mosaic
Glass: Framed sliding door sized to the existing alcove

Where to go next

Questions about this project

Do older Boise bathrooms always turn up rot?: Not always, but often enough that we scope pre-war homes with framing repair as a possibility rather than a surprise. On this project the damage was limited to two studs and a section of subfloor.
Can a cast-iron tub be removed from a small upstairs bathroom?: Yes. They come out in pieces rather than whole. It is loud and dusty for an hour, and it is far safer than trying to carry several hundred pounds down a narrow staircase.