Kitchens and bathrooms
Shower is leaking behind the tile - what went wrong?
Short answer
Almost always the waterproofing, not the grout. Grout was never waterproof; the membrane behind the tile is what keeps water out. Once water has been getting behind for a while there is usually wet framing, so a surface repair is money thrown away.
Grout is not the problem
Grout is a filler between tiles. It is porous by design and it was never the waterproof layer. When a shower leaks, what has failed is the system behind the tile, and re-grouting buys you a season at most.
What actually failed
- Cement board installed with no membrane over it.
- A pre-formed pan that was never sloped correctly, so water stands.
- A membrane that was not lapped up the curb and into the corners.
- A mixed system, where two incompatible waterproofing products meet and neither manufacturer will stand behind the joint.
Why the honest fix is a tear-out
By the time it is visible outside the shower, water has usually been in the wall for months. That means wet framing and sometimes mould, and neither is fixed from the tile side. The repair is normally a tear-out to the studs on the wet wall, new waterproofing installed as a single system, then tile.
I would rather tell someone that at the start than sell them a re-grout that fails in eight months and costs them the same money twice.
Making the next one last
- One manufacturer system throughout: pan, membrane, corners, bonding flange.
- Slope and flood-test the pan before any tile goes on.
- Waterproof the full height of the wet wall, not just the lower band.
- Silicone, not grout, in every change of plane — corners and the floor-to-wall joint move.
If you are rebuilding anyway, it is the moment to consider converting the tub to a walk-in shower. For the money side, what a bathroom costs here.
How to tell how far it has gone
- Staining or soft drywall on the other side of the wet wall.
- A musty smell that is stronger near the shower.
- Loose or hollow tiles low down, especially at the corners.
- Damage to the skirting or the floor outside the shower.
Any of those means water has been leaving the shower for a while. At that point a moisture meter on the adjacent framing tells you whether this is a shower repair or a shower and a wall, and it is worth knowing before anyone quotes.
Krisi Kakarova, World Properties Group
A licensed Florida Realtor (SL3327932) and a Certified Residential Building Contractor (CRC1335654), working in Seminole, Orange and Volusia County. Holding both is why these answers price the transaction and the construction together — more about how I work.
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