We're occasionally the first call in a bathroom remodel. More often we're the call two years after — when the beautiful new tile has to come up because of what was left underneath it. Every mistake on this list comes from a real job where someone's finished bathroom became a plumbing access panel. Learn from their contractors.
1–2: Entombing old pipes in new finishes
Mistake one: tiling over original galvanized supplies or a corroded cast-iron drain because 'they're working fine.' The remodel is the cheapest moment those pipes will ever have to be replaced; two years later, the same work requires demolition. Mistake two, its underground cousin: not scoping the drain lines before a major remodel. A camera inspection costs a fraction of one square meter of imported tile and reveals whether the lines beneath deserve the finishes above.
3–4: Slope and venting shortcuts
Mistake three: shower pans and curbless floors without correct slope — water finds the low corner, then the wall, then the ceiling below. Mistake four: skipping proper venting when fixtures move. A relocated toilet or a new freestanding tub needs vent geometry, not just a drain connection; the symptoms of bad venting — gurgling, slow drains, trap siphoning, sewer smell — arrive after the walls close and are miserable to retrofit.
5–6: Valve and access decisions
Mistake five: burying valves with no access. Every shower mixing valve and shutoff eventually needs service; a remodel that provides no access panel schedules a future tile demolition. Mistake six: reusing tired shutoffs and supply lines behind gleaming new fixtures — the twenty-dollar parts that fail and flood the new floor. Every remodel should include new stops and supplies as a matter of course.
7: The flange and the floor
Mistake seven, the most common of all: new tile raising the floor height above the toilet flange without correcting the flange. The toilet then sits on a recessed flange, sealed by hope and a doubled wax ring, rocking slightly — and leaking at every flush into brand-new subfloor. The correct fix during tiling is a flange spacer or replacement set to the new floor height. It's a small item on remodel day and a floor replacement afterward.
The pattern: remodel day is when plumbing corrections are cheap and afterwards is when they're heartbreaking. Have the rough plumbing assessed before finishes go in. Lumin Drain NJ provides pre-remodel inspections, rough-in work, and fixture setting across New Jersey: 929-662-1816.