You can spend a fortune on beautiful tile, premium fixtures, and a stunning vanity - but if the waterproofing behind it isn't done correctly, your bathroom remodel has an expiration date.
Waterproofing is the single most important step in any shower or tub area renovation. It's also the step that gets cut or rushed by contractors trying to save time. Here's why it matters and what to look for.
What Waterproofing Actually Does
Tile and grout are not waterproof. They're water-resistant at best. Over time, water works its way through grout joints and behind tile. Without a proper waterproof membrane behind the tile:
- Water seeps into the wall cavity causing mold, rot, and structural damage
- Subfloor deterioration leads to soft spots, cracked tile, and eventually floor failure
- Damage to adjacent rooms: water travels, and you might not notice a leak until it shows up as a stain on the ceiling below
In Chicago's older homes, this is especially risky because many buildings have plaster walls and wood framing that are particularly vulnerable to moisture.
The Right Way to Waterproof a Shower
A properly waterproofed shower uses a system, not just a single product:
1. Cement board substrate
Drywall (even "green board" moisture-resistant drywall) should never be used in a shower. Cement board (Durock, HardieBacker, or similar) provides a stable, non-organic substrate that won't deteriorate when exposed to moisture.
2. Liquid or sheet membrane
This is the actual waterproofing layer. Options include:
- **Liquid-applied membranes** (RedGard, Hydroban, Laticrete Hydro Ban) - painted on in two coats
- **Sheet membranes** (Kerdi, Noble) - bonded directly to the substrate
- Both work well when applied correctly; the key is full coverage with no gaps
3. Sealed seams and penetrations
Every joint, corner, pipe penetration, and transition point needs to be sealed with membrane and reinforcing fabric. These are the most common failure points.
4. Proper slope to drain
The shower floor must slope at a minimum of 1/4 inch per foot toward the drain. This prevents standing water and ensures everything flows where it should.
Red Flags During a Remodel
If your contractor is doing any of these, ask questions:
- Tiling directly over drywall in a shower: this will fail
- Skipping the waterproof membrane: "the tile is waterproof" is not true
- Only one coat of liquid membrane: two coats minimum, applied perpendicular to each other
- Not waterproofing the shower curb: the curb is one of the most common leak points
- Rushing the cure time: liquid membranes need proper drying time between coats and before tiling
The Shower Pan: Get This Right
The shower pan (floor) is where most leaks originate. A properly built shower pan includes:
- Pre-slope under the waterproof membrane that directs water to the drain
- Waterproof membrane covering the entire floor and extending up the walls at least 3 inches above the finished curb height
- Weep holes in the drain assembly that allow trapped water to exit
What Good Waterproofing Costs
Proper waterproofing is a small addition to the overall project compared to the cost of ripping everything out and starting over when a shower fails. It's the best insurance you can buy.
Our Approach
At AAA Construction, waterproofing is non-negotiable. We document the waterproofing process with photos before tile goes up, and we use manufacturer-approved systems that carry material warranties. It's the part of the job you'll never see once it's finished - and that's exactly the point.
Questions about your upcoming remodel? Let's discuss your project.
