Shower leaking into the room below in my Calgary home, source?

Shower leaks that show up in the room below are almost always one of four things, and pinning down which one matters before anyone opens a ceiling or wall.

Where the water is actually coming from

The most common source is the shower pan or liner. In a tiled shower, the waterproof liner sits beneath the tile and mortar bed; a crack, a failed seam or a deteriorated drain collar lets water through slowly, and it travels along the subfloor before dripping through to the ceiling below. You may not see standing water in the shower itself, which is what makes this one deceptive.

The second source is the drain assembly. The connection between the drain body and the liner, or between the drain and the drain pipe below, can work loose over time. A slow drip here only happens when the shower runs, so the staining below tends to appear after showers rather than continuously.

Third is the supply plumbing: the valve body, the shower arm connection at the wall, or a fitting behind the tile. A supply leak runs whenever the water is on and sometimes between uses if a cartridge is failing. This one is more urgent because it can wet framing and insulation continuously.

Fourth, and often overlooked, is the grout and caulk. Failed grout joints or a cracked caulk bead at the wall-to-floor junction let water into the substrate during every shower. This is slower damage, and it shows up more as tile and grout age.

A plumber's first step is to isolate which source it is before cutting anything open. A simple dye test (food colouring in the drain area) can confirm whether the liner is holding. Running the shower with the drain plugged tests the pan separately from the drain pipe. Running only the supply without the drain open tests the valve and supply connections.

On the ceiling side, the location of the stain relative to the drain and the supply valve gives a plumber a strong starting clue. A stain directly below the drain points to the drain assembly or liner; a stain toward the wall where the valve sits points to supply plumbing.

Permit and who should do the work.

Paid work on the shower valve and drain piping in Calgary is for a certified journeyperson plumber or a registered apprentice working under one, under Alberta's Skilled Trades and Apprenticeship Education Act. Under Alberta's Permit Regulation, changing a valve, trap or fixture without changing the piping does not need a plumbing permit; altering or adding to the piping does, and the City of Calgary issues that permit. The plumber should confirm which applies once the source is found.

Before hiring, ask to see the plumber's trade certificate and a WCB-Alberta clearance letter, and check that any deposit is covered by an Alberta prepaid contracting licence (Service Alberta).

A written quote for this job should include the diagnostic method, the scope once the source is confirmed, whether the ceiling or wall will be opened and by how much, who patches it afterward, the permit if one is needed, and the labour warranty. When you have two quotes side by side, compare those line items rather than the totals, because a quote that excludes ceiling patching or the permit can look cheaper while costing more in the end.