Quick answer
Upper-floor shower leaks are almost always failed waterproofing, perished silicone, a cracked tray, or a leaking waste connection — not the supply pipes. Supply leaks run constantly; shower leaks only appear after the shower is used, which is the tell. Water tracks along joists for weeks before it shows on the ceiling below, so by the time you can see a stain the leak has usually been running for some time.
Common causes
- Failed waterproofing membrane under the shower floor
- Cracked grout or perished silicone at the floor-to-wall junction
- Leaking shower waste fitting where it passes through the floor
- Cracked acrylic tray flexing on an inadequately supported base
- Failed seal on the shower door frame letting water behind the tiles
- Blocked or slow waste causing the tray to pond above the waterproofing upstand
What you can do now
- 1Confirm the timing — a stain that appears only after showering rules out supply pipes
- 2Rake out and replace perished silicone at all internal corners, then re-test
- 3Block the waste, fill the tray shallowly and leave it standing to test whether the tray or the waste is at fault
- 4Check the door seals and whether water escapes past the frame onto the bathroom floor
- 5Stop using that shower until it is diagnosed — every use adds to the damage
When to call a professional
Book the same week. Long-running shower leaks rot timber floors, saturate insulation and eventually bring ceilings down, and the repair scope grows every week it continues. A plumber will isolate whether it is the waste, the tray or the waterproofing before anything is broken out — which determines whether this is a re-seal or a full re-waterproof and re-tile.
Typical cost in Johannesburg
Re-silicone R450 · Waste replacement R650–R1,200 · Re-waterproof R3,500+
Indicative ranges only. We provide written, itemised quotes before any work.
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