Bathroom problems

Failed waterproofing. Water passes through grout and through backer board. If there is no compliant lining or bonded membrane behind the tile, it soaks the framing instead of draining out. Nothing shows for years. Then you get a stain on the ceiling below, or a soft spot in the hallway floor, and the repair is a full demolition. Prevention is a one-time detail during construction; there is no retrofit.

The shower pan. The IRC requires the lining to extend at least 2 inches beyond the rough jambs and 2 inches above the finished threshold. If it is cut short or punctured by a fastener, water goes around it. This is why inspectors flood-test pans — and why you should ask whether yours was tested and photographed.

Ventilation. A bathroom with no fan, an underpowered fan, or a fan ducted into the attic instead of outdoors will grow mold no matter how good the tile is. The IRC's minimum local exhaust for a bathroom or toilet room is 50 cfm intermittent or 20 cfm continuous. Confirm the duct terminates outside the building, not into a soffit cavity or attic space.

Rot found mid-project. This is the most common cause of blown budgets. This Old House reports roughly 70% of homeowners doing tub-to-shower conversions encountered unexpected costs. It is not usually a contractor gouging you — it is what was behind the wall. Which is exactly why the change-order rate belongs in the contract before demolition starts.

How to choose

Watch the ceiling below the bathroom

A stain or a nail pop on the ceiling under a shower is the earliest visible sign of a leak. Investigate then, not when the floor gets soft.

Push a fingertip along the base of the toilet and tub

Spongy flooring or lifting caulk at the base means water has been getting under the finish. It gets worse, never better.

Insist on a flood test of the shower pan

Plugging the drain and filling the pan is the standard verification. Ask that it be done and photographed before tile.

Verify the fan ducts outdoors

Go into the attic and look. A duct dumping moist air into insulation is a common and serious defect.

Get the change-order rate in writing

Before demo, agree what per-hour and per-material rates apply to hidden damage. It converts a fight into an invoice.