What it usually looks like
- A yellow or brown ring on the ceiling directly below a toilet, tub or shower
- Bubbling or sagging drywall, or paint peeling in a patch
- A drip from a ceiling light fixture or fan below the bathroom
- The stain darkens or spreads after someone showers
- The toilet upstairs rocks slightly or the floor around it feels soft
- A musty smell in the room below, strongest in the morning
Likely causes, most common first
Failed wax ring or loose toilet
The wax seal between the toilet and the flange gives out when the toilet rocks, the flange is below the finished floor, or the bolts corrode. Each flush sends a little water into the subfloor. The stain is usually offset a bit from directly under the toilet, because water follows the joists. This is the most common source we find in the 1960s and 70s two-story homes around Bremerton and Port Orchard.
Tub drain or overflow gasket leaking
The drain shoe under the tub and the overflow plate behind the tub spout both rely on rubber gaskets. They dry out, the drain shoe corrodes, or the slip joint under the tub loosens. Water escapes only while the tub is draining or when someone fills it high enough to use the overflow. The stain appears after baths and showers, not flushes.
Shower pan, tile or grout failure
A tile shower depends on a waterproof pan under the tile and sealed corners. Cracked grout in the corners, a failed liner or a curb with no waterproofing lets water into the floor. These leaks are slow, show up after long showers, and get worse over months.
Supply line or shower valve leak in the wall
A pinhole in copper, a loose compression nut on a toilet or sink supply, or a cracked shower valve body will leak around the clock. The stain grows whether or not anyone uses the bathroom, and the water meter moves with everything off. This one causes the most damage because it never stops.
Caulk and splash water at the tub rim
Where the tub meets the tile, a gap in the caulk lets shower spray run behind the tub. It looks like a drain leak but shows up only after showers with the curtain or door not fully closed.
Condensation or a roof and vent leak
A bath fan duct that is uninsulated in the attic drips condensation back down in winter, and a roof leak around a plumbing vent flashing can stain a ceiling near a bathroom. The weather and the season give these away.
Safe things to check yourself first
- Do not flush or shower for a day and mark the edge of the stain with a pencil. If it grows anyway, you have a supply leak; shut the main.
- Read the water meter with everything off and read it again in thirty minutes. Movement confirms a pressurized leak.
- Run a controlled test: flush the toilet several times and watch the stain, then the next day fill and drain the tub, then run the shower for fifteen minutes, waiting between tests.
- Press on the floor around the toilet base and try rocking the bowl. Any movement means the seal is suspect.
- Pour water directly around the tub drain and overflow with a cup, without running the faucet, to isolate the drain from the valve.
- Check the caulk at the tub rim and the corners of the shower for gaps and cracks.
Stop and call if
- The ceiling is sagging, bulging or dripping steadily
- Water is coming through or near a light fixture, fan or outlet
- The stain grows with the bathroom unused and the meter is moving
- The toilet is loose and the floor around it is soft, which means subfloor rot
- You can smell sewage below the bathroom
How we diagnose and fix it
- Run the same controlled fixture tests, often with a moisture meter on the ceiling and thermal imaging, to identify the source before any ceiling is cut.
- Reset the toilet with a new wax or waxless seal, replace a corroded or broken flange, and shim and secure the bowl so it cannot rock.
- Replace tub drain and overflow assemblies, including the slip joints and gaskets, from above or through the ceiling below when there is no access panel.
- Repair or replace a leaking shower valve, supply stop or pinholed pipe in the wall, and pressure-test the repair.
- Advise plainly when a tile shower has a failed pan, which is a rebuild rather than a repair, and quote the plumbing side of that project.
- Open the smallest possible ceiling section when needed, keep it neat, and document the source for your insurance claim and the drywall contractor.
Around Kitsap, Pierce and Mason counties
Two-story homes are a smaller share of the housing stock here than ramblers, but the split-levels and tri-levels built around Bremerton, East Port Orchard and University Place in the 1970s put bathrooms over living rooms and garages, and those are the ceiling stain calls we get most. Older tubs in those homes have original brass drain shoes that are corroded through. The damp climate makes it worse: a slow leak that would dry out between uses in a drier region stays wet from October to April here and grows mold behind the drywall before the stain is even visible.
Questions people ask
Do you have to cut the ceiling to find the leak?
Not usually to find it. Testing fixtures one at a time with a moisture meter on the ceiling identifies the source most of the time. Repairs to a tub drain sometimes need a small opening below, and we cut it clean so the patch is simple.
Can I just paint over the stain once the leak is fixed?
After the drywall has dried completely, usually a week or two, prime it with a stain-blocking primer and paint. If the drywall is soft, crumbling or shows mold, the section should be replaced instead.
Why does the stain only show up in winter?
Either it is condensation from an uninsulated bath fan duct, or a slow leak that evaporates in summer stays wet in the damp months. The fixture tests above tell which.
Is a leaking wax ring a big repair?
Usually not, if caught early. The toilet is pulled, the flange checked, a new seal set and the toilet reinstalled in about an hour. If the subfloor has rotted, that becomes a carpentry repair before the toilet goes back.
Who fixes the ceiling after the plumbing is repaired?
A drywall or restoration contractor. We fix the leak, make the access opening as small as practical and write up what we found, which is what your insurance and the drywall contractor need.