Repair Systems — 01
Cementitious flexible waterproofing membranes
Technical product reference for two-component polymer-modified cementitious waterproofing membranes. Covers product classification, AS 4858 class ratings, system selection, application requirements, and brand comparisons for Australian Class 2 strata building applications.
What are flexible cementitious waterproofing membranes?
Flexible cementitious membranes are polymer- or latex-modified cementitious coatings (1- or 2-component) that bond tenaciously to concrete and masonry — including damp/SSD substrates — to form a flexible, crack-bridging waterproof layer. They are used under tile and screed for balconies and wet areas, and (in negative-side-rated grades) for below-grade, foundation, pool and tank waterproofing. Selection turns on components (1C vs 2C), AS 4858 flexibility class, crack-bridging, positive- vs negative-side capability, and whether the product is exposed/trafficable on its own or only when overcoated with a UV/wear top coat.
Class 2 (NCC) — balconies, roofs & podiums: specify only a membrane with current Australian test certification (see the “Class 2 / NCC tested” field on each card). A product shown as N/A is unverified — not a substitute for a certified system.
Product Reference
Individual products — one card each — scroll to view all
ARDEX Australia
ARDEX WPM 002
2-part modified cementitious membrane — under tile/screed
ARDEX WPM 002 is a two-part modified cementitious waterproofing membrane (Part A liquid 20 kg + Part B powder 20 kg) compliant to AS 4858 and AS 4654, applied in 2 coats under tiles, screeds and paver/decking systems internally and externally (16–24 m² per 40 kg kit). Recoat 1–2 h; ready to tile 24 h; full cure 3 days; primer WPM 300/265/368/Multiprime. CONFIRM AS 4858 class and crack-bridging against the current Ardex Australia TDS.
Mapei Australia
Mapei Mapelastic Smart
2-component high-flexibility cementitious mortar
Mapei Mapelastic Smart is a two-component, high-flexibility cementitious mortar with crack-bridging >2 mm and 170% elongation (AS/NZS 4858 Class II, tested by CSIRO; AS 4654.1 exposed, non-trafficable), applied by trowel or roller for waterproofing balconies, terraces, bathrooms and swimming pools. CONFIRM coverage, DFT and primer against the current Mapei Australia TDS.
Mapei Australia
Mapei Mapelastic Foundation
2-component flexible cementitious — positive/negative side
Mapei Mapelastic Foundation is a two-component, flexible cementitious mortar for waterproofing concrete and masonry under positive or negative water pressure — basements, pools, foundations and below-grade structures. CONFIRM AS 4858 class, crack-bridging, coverage and primer against the current Mapei Australia TDS.
Davco / Sika Australia
Davco K11 Flex
2-part acrylic-modified cementitious membrane
Davco K11 Flex is a flexible, 2-part acrylic-modified cementitious waterproofing system whose components react to a hard, elastic film bonded to concrete and masonry. Applied by brush or float over a saturated (SSD) substrate; first coat ~1–1.5 kg/m², wet film 0.7±0.1 mm per coat. CONFIRM AS 4858 class, crack-bridging, total coats/DFT and primer against the current Davco / Sika Australia TDS.
Fosroc / Parchem
Fosroc Nitoproof 410
Water-based 2-part polymer-modified cementitious (fast-dry)
Fosroc Nitoproof 410 is a water-based, fast-drying, flexible two-component polymer-modified cementitious waterproofing membrane (Part A 12.5 L + Part B 12.5 kg) for under toppings, tiles and other protected environments. It may be used as a foot-trafficable exposed roof or balcony deck membrane only when overcoated with Nitoproof Top Coat UV. CONFIRM AS 4858 class, crack-bridging, coverage and primer against the current Fosroc / Parchem TDS.
Sika Australia
Sika Sikalastic-1K
1-component fibre-reinforced flexible cementitious
Sika Sikalastic-1K is a one-component, fibre-reinforced cementitious mortar for flexible waterproofing. The AU TDS PDF was not machine-readable at time of writing — CONFIRM AS 4858 class, crack-bridging, coats/DFT, coverage and primer against the current Sika Australia Sikalastic-1K TDS.
Westox Building Products
Westox Flexible Cement Membrane (FCM) Kit 18 kg
2-component latex-cementitious membrane (Australian-made)
Westox Flexible Cement Membrane (FCM) is a two-component, latex-based cementitious emulsion that mixes to a flexible waterproof coating — 100% Australian-owned and made. Apply a minimum of 2 × 1 mm coats at approximately 1 m² per litre per coat. CONFIRM AS 4858 class, crack-bridging, primer and substrate prep against the current Westox TDS.
System Comparison
Flexible cementitious membranes — confirm all selections against the current manufacturer TDS before specifying.
Scroll the table sideways to see every column →
Do not confuse cementitious flexible membranes with:
- Polyurethane and hybrid liquid membranes (ARDEX WPM 157, Sikalastic-487, Bostik Dampfix PU, Gripset P39 and similar) — these are polymer-based, not cement-based, and typically have higher elongation — listed on the liquid applied PU and hybrid membrane page
- Single-component acrylic and SBR membranes (Crommelin Wetite, Gripset 38FC and similar) — water-based polymer systems, not cementitious — listed on the liquid applied acrylic membrane page
- Crystalline waterproofing (Xypex, Krystol and similar) — penetrating admixture systems, not surface-applied membrane-forming products
- Rigid cementitious coatings — non-flexible cement coatings such as Maxseal Super or similar rigid tanking products — not the same as flexible two-part polymer-modified systems
- Epoxy moisture barriers — two-part epoxy primers applied under floor adhesives — these are moisture barriers, not waterproof membranes
- Sheet membranes — factory-manufactured sheet products (torch-on bitumen, self-adhesive butyl) — not liquid or trowel-applied systems
Disclaimer
This page provides general technical information only. Final product selection must be confirmed against the current manufacturer technical data sheet, project specification, substrate condition, exposure level, drainage, required finish, NCC requirements, AS 4858 and AS 4654 requirements where applicable, and applicator warranty conditions. Do not rely on this reference as a substitute for professional engineering or waterproofing consultant advice.