A bathroom is the only room in a house that gets deliberately soaked several times a day, every day, for decades. It is also the room where almost all of the engineering is invisible by the time the job is finished. That combination is why bad bathrooms get built. On the day the last piece of trim goes on, a bathroom built properly and a bathroom built badly look exactly the same — and they will keep looking the same for two or three years.
Here is the thing most homeowners are never told. Tile is not waterproof. Grout is definitely not waterproof — it is cement, and cement is porous by design. Water passes through a tiled surface routinely and in normal use. Everything therefore depends on what that water hits next, and on whether it can get back out.
In a bathroom built correctly, what it hits is a waterproofing assembly: cement backer board rather than paper-faced drywall on every wet wall, a waterproofing membrane rolled or sheeted over that and lapped into the corners and up from the pan, and a shower floor sloped consistently to the drain and flood-tested before anything decorative goes near it. In a bathroom built badly, what it hits is ordinary drywall, or backer board with no membrane at all, and it soaks into the studs.
Nothing visible happens for a while. That is the trap. Water wicks into the framing, the framing stays damp because there is no way for it to dry, and the damage accumulates out of sight. By the time it announces itself — a soft spot in the floor near the tub, grout that will not stay put in one corner, a stain appearing on the ceiling of the room below — the repair is no longer a bathroom job. It is a framing job with a bathroom on top of it.
The shower pan deserves its own paragraph, because it is where the most expensive mistakes happen. A pan has to slope to the drain at a consistent fall across its whole area, and the waterproofing layer underneath has to slope with it. A pan that is flat in one corner holds water permanently under the tile. A pan waterproofed flat and then sloped with mortar on top drains the tile surface but keeps a permanent reservoir sitting on the membrane. Both are invisible. Both eventually smell.
There is a simpler failure worth knowing about too, and it accounts for a lot of the rotten subfloors we find: the joint between the tub and the tile above it. That joint moves — a filled tub with a person in it deflects measurably — and it must be sealed with flexible sealant, not grouted. Grout in that joint cracks within a season, and then every shower sends water straight down the back of the tub into the floor framing. It is a five-dollar detail that decides whether the floor is sound in ten years.
So what should you actually ask for? Ask what is going on the wet walls, and listen for cement board rather than 'moisture-resistant drywall' — green board is not a waterproofing product. Ask what membrane is being used and whether it is being lapped into the corners. Ask whether the pan will be flood-tested before tiling, and ask to see it. Ask whether the tub-to-tile joint will be sealed or grouted. Any contractor doing this properly will be pleased to be asked, because it is the part of their work that is otherwise impossible to see.
And if you have an existing bathroom showing signs — a persistently loose tile, grout that keeps failing in the same spot, a floor that gives slightly by the tub, a musty smell that cleaning does not fix — those are not cosmetic. That is the assembly telling you it has been letting water through for a while. It is a great deal cheaper to deal with at that stage than after the joists go.
Top Line Remodel LLC remodels bathrooms across Benson, Clayton, Garner, Raleigh, Durham and the rest of the Triangle. Call (919) 396-2777 for a free on-site estimate.