Shower Waterproofing.

The short version.

What you can actually pick.

• Schluter Kerdi sheet membrane

  Pros — Fast install, modular system, well-trained installer base, 10-year manufacturer warranty.

  Cons — Requires perfect substrate flatness, premium price for accessories (drains, curbs).

  $8–$14 / sqft of shower area30+ years

• Hot-mopped pan + cement-board walls

  Pros — Bulletproof when done correctly, code-compliant for decades, repairable.

  Cons — Few qualified crews remaining, longer install time, fumes during install.

  $10–$18 / sqft of shower area40+ years

• Liquid-applied (RedGard, Hydro Ban)

  Pros — Goes over any sound substrate, no seams, fast cure.

  Cons — Requires careful mil-thickness verification, less suited for floor pans.

  $6–$11 / sqft of shower area20–25 years

What we deliver.

• ▸Demo of existing shower down to studs and subfloor
• ▸Subfloor evaluation — repair any rotted plywood, sister joists if needed
• ▸Pre-slope mortar bed at 1/4 in per foot to the drain
• ▸Waterproofing membrane install per manufacturer spec
• ▸Niche framing and waterproofing (often the highest-risk leak source)
• ▸Curb framing and full waterproofing including outside face
• ▸Drain integration — bonding flange or two-part clamping drain per system
• ▸24-hour static pressure test, documented with photos
• ▸Mortar bed for tile, or direct-bond tile per manufacturer spec
• ▸Tile install with silicone (not grout) at change-of-plane joints
• ▸Final inspection before bath enclosure or fixtures

The code parts most owners miss.

• §ANSI A118.10 listing is required for shower membrane systems — verify on the manufacturer's data sheet before specifying.
• §Pan slope: 1/4 in per foot minimum to the drain (UPC §411.7).
• §Curb waterproofing extends up the outside face of the curb minimum 2 in (commonly 4 in for safety).
• §Niche waterproofing must wrap all three interior surfaces continuously — most niche leaks are at the corner seams.
• §Drain must be a bonding flange or clamping type compatible with the membrane — not a standard tub drain.
• §Change-of-plane joints (wall-to-floor, wall-to-wall corners) must be silicone, not grout — code-required (TCNA EJ171).

Why getting this right pays off.

What goes wrong — and how to avoid it.

• ✕Skipping the pre-slope — flat membrane pools water, leaks at curb or wall
• ✕Niche corner seams not double-lapped — leaks behind the tile, undetectable until framing rots
• ✕Standard drain instead of bonding flange — water bypasses membrane through the drain housing
• ✕Grout at change-of-plane joints — cracks within a year, water enters the substrate
• ✕Tile-installer waterproofing instead of dedicated waterproofing trade — different skill set
• ✕No 24-hour pressure test — leaks not caught until tile is on

After we hand you the keys.

• ▸Re-caulk silicone at change-of-plane joints every 3–5 years
• ▸Watch for grout cracks — repair within weeks (use mildew-resistant grout)
• ▸Pull and re-seal the shower drain cover annually
• ▸If you remodel the kitchen above, inspect the shower ceiling for any new movement
• ▸Treat any persistent dampness or mildew as a leak indicator until proven otherwise

In short.

What's the best shower waterproofing system?

Schluter Kerdi for most California bathrooms — well-trained installer base, predictable result, fast install. Hot-mopped is still the gold standard when you have a qualified crew. Liquid-applied works well for walls but is less suited for floor pans.

How much does shower waterproofing cost?

$1,800–$5,500 for a typical 35 sqft shower. Schluter $8–$14/sqft. Hot-mopped $10–$18/sqft. Liquid-applied $6–$11/sqft. These are the waterproofing layer only — tile, fixtures, and glass are separate.

Why do showers leak?

Almost always due to one of: skipped pre-slope, un-lapped niche corners, wrong drain type, or grouted (not siliconed) change-of-plane joints. All four are catchable with proper install practice and a 24-hour pressure test.

What's a pressure test and do I need one?

After waterproofing is complete and before tile starts, we plug the drain and fill the pan with water for 24 hours. Loss of more than 1/8 inch means there's a leak that must be repaired now, not after tile. Yes, you absolutely want this test.

Can I use a regular drain in a tiled shower?

No — tile-ready showers require either a bonding-flange drain (for sheet membranes) or a two-part clamping drain (for hot-mopped pans). A standard tub drain lets water bypass the waterproofing through the drain housing.

What about the niche — that always leaks, right?

Niches are a common leak source because the corner seams are easy to skip. Done correctly (corners double-lapped, membrane continuous on all interior surfaces, slope toward the shower for water evacuation), niches are leak-free for decades.

How long does shower waterproofing last?

Properly installed Schluter or hot-mopped: 30–40 years. Liquid-applied: 20–25 years. Re-caulking the silicone joints every 3–5 years extends life. The waterproofing layer itself doesn't fail with age — installation errors fail.

Do I need a curb?

Most CA showers have a 4–6 in curb that contains water and gives a clean transition. Curbless (zero-threshold) showers are increasingly popular for aging-in-place and aesthetics — they require a recessed subfloor and a linear drain, adding $1,500–$4,000 to the project but are fully waterproof when designed correctly.

Keep reading.

• Shower Glass Enclosure

  Custom-templated tempered glass — frameless is the standard now.