Guided evidence worksheet
Shower leak paths: splash, drain, supply and waterproofing
Change one condition at a time: supply pressure, drain loading, spray location and standing water. Record the delay to the first leak.
Reasoning guardrail
Separate the routes before choosing a repair.
A wet ceiling below the shower does not identify whether the drain, supply or waterproofing failed.
- Trigger
- Leak timing during spray, standing water and fixture use is the strongest separator.
- Area
- Bathroom
- Provenance
- Original explanatory diagram, not a site photograph.
1. Freeze the evidence
What happened first?
2. Competing hypotheses
Record evidence for and against each route.
Pressurized supply or valve leak
A fitting or supply route leaks while the valve is open, even when water does not reach the drain.
Evidence that raises fit
Evidence that lowers fit
Notes
Drain body or waste connection leak
Water escapes when the drain or trap receives flow or standing water.
Evidence that raises fit
Evidence that lowers fit
Notes
Waterproofing transition or splash escape
Water crosses a wall, curb, door or penetration boundary during spray exposure.
Evidence that raises fit
Evidence that lowers fit
Notes
3. Decision points
Change one condition at a time.
Does the leak occur with the valve on while water is captured before it reaches surfaces and drain?
Yes: Move pressurized supply components to the front.
No: Separate drain loading from spray exposure.
Observed answer and evidence
Does a drain-only test reproduce the leak?
Yes: Prioritize drain body, trap and waste connections.
No: Map spray direction, curb and waterproofing transitions.
Observed answer and evidence
Safety boundary
Stop rather than create a better clue.
- Stop testing if water approaches lights, wiring or an occupied ceiling cavity.
- Do not perform repeated flooding tests that can increase concealed damage.
5. Current conclusion
