Why fixing/waterproofing matters

Of all new-home defects, waterproofing failures are the most expensive to fix retrospectively. A bathroom that leaks in year 2 means:
– Tile removal
– Substrate replacement (usually mouldy)
– Re-waterproofing
– Re-tiling
– Re-grouting

Cost: $8,000–$25,000 per bathroom. All preventable by inspecting at fixing stage before the tiles go down.

What we check at fixing/waterproofing

A thorough fixing-stage inspection covers:

Waterproofing

• Coverage — every wet-area floor and 150mm minimum up walls (more in showers per AS 3740)
• Membrane integrity — no pinholes, tears, or thin patches; correct membrane type for the substrate
• Penetrations — every plumbing fixture penetration sealed and reinforced; correct flange detail
• Floor falls — minimum 1:80 to floor wastes; no flat spots; no back-falls
• Hob heights — shower hobs at correct height; thresholds at correct fall
• Junction details — wall/floor junction reinforced with bond breaker fillet; correct treatment at corners

Internal fit-off readiness

• Door installation — frames plumb and square; consistent reveals; correct strike plate alignment
• Architraves and skirting — mitres tight, scribes correct, fixings concealed
• Cornices — uniform; no visible joins; no cracks
• Pre-paint substrate — sanded smooth, no visible joints/tape, dust controlled

Tile-readiness

• Substrate flatness — within AS 3958.1 tolerance for the chosen tile size (large-format tiles need flatter substrates)
• Cement sheet substrate — fixings flush, taped joints, ready for tile adhesive
• Tile setout — visualise the tile pattern; flag any obvious set-out issues now

Other

• Insulation — final pass; no compressed insulation or missing patches
• Service penetrations — sealed against vermin and air infiltration

Common defects we find at fixing/waterproofing

• Membrane not extended high enough up shower walls — AS 3740 minimum height not met
• Floor waste not at the lowest point — water pools instead of draining
• Pin-hole gaps in membrane at corners or penetrations — invisible until water finds them
• Tile set-out issues — small slivers at thresholds, awkward cuts at corners
• Door reveals inconsistent — 3mm one side, 8mm the other
• Cornice cracks at frame stage carried forward — should have been remedied
• Skirting scribes poor — visible gaps between skirting and uneven floors

Why VBA-registered inspectors matter here

Waterproofing inspection requires reading AS 3740 against the as-applied membrane. A VBA-registered builder has installed waterproofing membranes — they know what a properly applied membrane looks and feels like, where defects hide, and what corner detail tells you the work was rushed.

A generic inspector who’s never installed a membrane will tell you “looks fine.” A registered builder will catch the missing reinforcement at the floor waste flange.

Frequently asked questions

When is fixing/waterproofing stage inspected?

After plasterboard is up, waterproofing is applied to wet areas, but before tiling. Your builder will notify you when the stage is reached.

How long does the inspection take?

1-1.5 hours on site for a standard 4-bedroom home. Same-day photo-rich written report.

Will the builder fix waterproofing defects?

Yes, contractually they must. Waterproofing must comply with AS 3740 and the NCC. Documented defects = punch-list items.

What if tiling has already started?

Then it’s late. Stop work, document, and have the inspection done before more tile goes down. Removing tile to fix waterproofing is feasible but costly.

Book a fixing stage inspection

New Home Stage Inspections — Melbourne West — VBA-registered builder, four-stage inspections, same-day reports.

Related guides:
– The 5 Stages of a New Home Build
– Lock-Up / Pre-Plaster Inspection Guide
– PCI Checklist — Practical Completion Handover

Call Michael direct on 0412 014 216 to book.