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What Is Involved in a Waterproofing Inspection?

A waterproofing inspection isn't just "look at the membrane and tick a box." Done properly, it's a structured staged audit that captures evidence at the points where waterproofing actually succeeds or fails: substrate prep, junction detailing, membrane thickness, terminations, and final flood-test performance. Here's what we actually do on site and what ends up in the report.

1. Pre-Membrane Substrate Inspection

Before any membrane goes down we check the substrate is dry (moisture meter readings logged), free of laitance, dust and bond-breakers, and falls have been formed to satisfy AS 3740 / AS 4654.2 minimums. A flat or back-falling substrate gets red-flagged before the membrane is applied — once the membrane is down, fall correction means a screed topping or full removal.

2. Bond-Breaker and Detailing Check

We verify bond-breaker tape is in place at every movement joint, pipe penetration is properly sleeved, and floor wastes have been recessed and dressed with a flange (not just a hole in the slab). Internal corners get checked for fillets, and external corners for sheet-membrane reinforcing patches.

3. Membrane Application — During and After

• Sheet membranes — laps measured (typically 50–100 mm), heat-welded or self-adhered with proper roller pressure, no fish-mouths or air pockets.
• Liquid membranes — wet film thickness checked with a comb gauge during application; dry film thickness verified afterwards with a Tooke gauge or destructive coupon at agreed locations.

Manufacturer-specified dry film thickness is the single most-cheated parameter on liquid jobs. We measure it.

4. Termination and Upturn Verification

Internal upturns are checked against AS 3740 (≥150 mm above FFL at shower walls). External upturns are checked against AS 4654.2 Table A1, which sets the height based on the project wind classification — not a fixed 150 mm. For higher wind regions, you need 100 mm, 150 mm or 180 mm upstands. Most failures we see come from contractors defaulting to "150 mm everywhere" without checking the wind class.

5. Flood Test

Where the deck is flood-testable, we witness a 24-hour ponded flood test to AS 4654.2 with the outlets dammed and water depth photographed. A failed flood test gets traced to a specific junction or termination and rectified before tiles or topping go down.

6. Report and Documentation

The inspection report you receive contains: location plan with each inspection point pinned, dated photos at every stage hold, DFT readings, flood-test results, a defect log with rectification recommendations, and a signed certificate of compliance referencing the specific Australian Standards verified. This is the documentation pack a certifier, insurer or strata committee actually needs — not a single-page "all good" letter.