Quick answer: A walk-in shower that lasts is built in layers you never see: a properly sloped and waterproofed shower pan, cement board walls instead of drywall, a waterproofing layer over the walls, and carefully sealed niches, benches, and valve openings. Tile and grout are not waterproof on their own. If the layers behind the tile are wrong, the shower will leak into the walls and subfloor no matter how good the tile looks.
The Layers of a Well-Built Shower
- Framing and blocking: solid backing for the bench, niche, grab bars, and glass.
- Valve rough-in: the shower valve set at the right depth so the trim fits after tile.
- Shower pan: sloped to the drain and waterproofed so water can’t sit or soak into the floor.
- Cement board walls: in the Longmont remodel shown above, USG Durock cement board went on the shower walls, bench, and niche.
- Waterproofing: a membrane over the cement board, with corners, seams, and every penetration sealed.
- Tile and grout: the finish layer, installed last.
Niches and Benches Need Extra Care
A recessed niche and a built-in bench are the most common leak points in a custom shower. Both have flat surfaces where water sits, so they need slope toward the shower and fully sealed corners. The niche in this project was framed and built into the cement board before waterproofing.
Signs an Old Shower Was Built Wrong
- Loose or hollow-sounding tiles.
- Grout that keeps cracking or turning dark.
- Soft floor or stains on the ceiling below the bathroom.
- A musty smell that doesn’t go away.
For budgets, see our bathroom remodel cost guides.
Frequently Asked Questions
What goes behind tile in a shower?
Cement board or another tile backer over the framing, then a waterproofing membrane, with a sloped, waterproofed pan on the floor. Regular drywall should not be used in a shower.
Is grout waterproof?
No. Grout and tile shed water but let moisture through. The waterproofing behind the tile is what keeps water out of the walls and floor.
Can a tub be converted to a walk-in shower?
Yes. A tub-to-shower conversion is a common bathroom remodel. The floor, drain, and valve are reworked and a new waterproofed shower is built in the space.
Planning a shower remodel? Josh Brooks Construction and Renovation is a licensed general contractor in Longmont with 30 years in construction. Call 720-828-7997 or text 720-453-5095.
