Moisture in the shower
The following diagram has been simplified for illustrative purposes and is largely self-explanatory.
Component Breakdown:
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Stud wall
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Blue board or water-resistant substrate – The surface to which tiles are adhered, following application of the waterproof membrane
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Waterproof membrane – Applied over the substrate to prevent moisture ingress
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Tile adhesive and grout
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Tiling surface – Typically ceramic or porcelain tiles
A properly constructed shower recess is designed to accommodate a degree of moisture between the tile surface and the waterproof membrane. Moisture within this zone is acceptable, provided it does not breach the membrane.
Our instruments detect moisture within a depth field of up to 30mm. However, this reading cannot determine the exact position of the moisture relative to the membrane without invasive investigation (i.e., wall delamination), which is beyond our inspection scope. Accordingly, moisture presence in this context is not automatically considered a defect.
The blue area in the diagram highlights a typical zone subject to surface moisture from porous tiles – a common issue due to the widespread use of budget-grade tiles in modern construction. Ideally, quality tiles should be non-porous, allowing the moisture meter to return a dry reading.
If elevated moisture levels are detected, we recommend the following:
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Engage a licensed plumber to conduct a water pressure test to rule out plumbing leaks behind the membrane
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Check that tapware penetrations are adequately sealed to prevent water tracking behind the waterproofing
Finally, always request warranties or receipts for any repair or construction work on the shower recess, particularly if the works are less than 7 years old, as these may still fall under statutory warranty or builder liability.
