Testing, Inspection, and Quality Control
What this domain tests
Testing confirms the assembly before it is buried. Candidates must know the flood test (plug the drain, fill to a specified depth above the highest point of the membrane, hold for a specified period, inspect from below), inspection hold points, and documentation.
Key concepts
- Flood test is performed after the membrane is complete and before tile or the top bed covers it.
- Water depth is measured above the highest point of the membrane, not the drain.
- The test period is a defined duration; the assembly must be observed for level loss and inspected from the underside where accessible.
- Hold points: preslope inspection, membrane inspection, flood test, and final slope verification.
Traps
- Flood testing after the top mortar bed is installed - the membrane is no longer visible or testable.
- Measuring water depth at the drain, which understates the depth at the high point.
- Accepting a test with no observation record or with the drain plug leaking.
- Skipping the underside inspection when the ceiling below is accessible.
Rule of thumb
Test the layer you cannot see again. If the next trade will bury it, it gets tested and documented first.
Worked example
A flood test shows 1 in. of water at the drain but only 1/2 in. at the far corner. Correct reading: depth is measured at the highest point of the membrane, so the test depth is 1/2 in. - likely below the required minimum, meaning the test is invalid and must be redone at proper depth.