Duram 195 Waterproofing Membrane

Duram 195 is a single-pack, moisture-curing polyurethane waterproofing membrane that forms a tough, seamless Class III elastomeric barrier. It is used across roofs, decks, balconies, podiums, gutters, planter boxes and protected wet areas, with exposed applications requiring the Duram-specified protective top-coat system.

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How it works

Duram 195 uses a self-leveling, moisture-curing polyurethane chemistry that bonds directly to primed substrates, eliminating the risks of joints, seams, or laps. Unlike conventional aromatic polyurethanes, it incorporates UV stabilisers, UV absorbers, and antioxidants to provide enhanced stability during the construction phase. Because the formulation is completely bitumen and tar-free, it will not stain grout or tiles when covered. The cured membrane also inhibits mould and biological growth, protecting covered internal wet areas from under-tile degradation.

Numbers that matter

• Class III Elongation (400% at break): Tested to AS 4654.1 Appendix A, providing high elasticity to bridge thermal movement in exposed balconies, roofs, and timber-to-concrete junctions without rupturing.
• 1.5mm dry film thickness (DFT): The minimum required thickness for standard horizontal applications without a top coat, achieved by applying two coats at 0.75m² per Litre per coat (0.66mm WFT per coat).
• 1.2mm minimum DFT system spec: When applied as a system with Duram Multithane ATC top coat, the minimum dry film thickness is 1.2mm as per Test Report DC12517-002.
• 48-hour full cure: Based on standard conditions of 25°C at 50% Relative Humidity. Touch dry in 4 to 6 hours, with a recoat window of 6 to 24 hours.
• Low VOC (<100 g/L): Compliant with the Green Building Council of Australia (GBCA) Green Star environmental criteria.

Where to use it

Duram 195 is suitable for above and below-ground applications on clean, sound, and dry substrates including concrete, cementitious screeds, masonry, and lightweight composite sheeting. On exposed roofs, decks, terraces, balconies, podiums, and gutters, it must be top-coated with Duram Multithane ATC to prevent UV degradation. In tiled or covered wet areas, it provides long-term waterproofing under screeds and finishes.

Limitations

• Do not apply directly to damp or slightly damp surfaces, as this prevents adhesion and causes gassing and bubbling of the membrane. The surface must be completely dry.
• Not suitable for direct and prolonged contact with chlorine concentrations above 10 ppm.
• Not designed as a trafficable membrane; only infrequent maintenance foot-traffic is acceptable during construction.
• Direct tile adhesion is not advised. For direct-stick tile applications, seek technical advice from Duram. An unbonded screed is typically required.
• Do not use particleboard sheeting as a substrate for this waterproofing system.
• In exposed areas, the membrane must be coated with Duram Multithane ATC or covered to prevent slow degradation from direct sun exposure.

Surface preparation and priming

Cementitious substrates must be cured to a minimum compressive strength of 20MPa. Substrate moisture must measure below 75% RH via in-situ probe testing (ASTM F2170) or below 4.5% via non-destructive comparative testing (ASTM F2659). Slab-on-grade elements require an effective damp-proof membrane underneath. All laitance must be removed via shot blasting, sandblasting, or grinding to achieve a clean profile.

Lightweight sheeting must be dry, clean, and installed to the manufacturer's structural recommendations with all sheet edges supported on framing. Cut edges must be treated to maintain water resistance, and sheet joints must be detailed using Perm-a-fab, Duram Leak-Seal Tape, or a DualFlex Bandage.

Surfaces should be primed with Duram Primeseal MC at a rate of no less than 1 Litre per 4m² (or Duram Primeseal SP at 1 Litre per 7m²) and allowed to dry. If there is a risk of entrapped substrate moisture causing outgassing, apply two coats of Duram Primeseal MC. For metal surfaces, abrade to meet AS 1627.4 Class 2.5 and prime with Duram ME Primer.

Installation and detailing

For internal wet areas, install joints, fillets, and bond breakers in accordance with AS 3740 using a 12mm bead of compatible sealant. For external above-ground applications, install fillets in accordance with AS 4654.2 using a 15mm x 15mm bead of compatible sealant, and chamfer all external corners.

Treat non-structural static cracks under 1.6mm wide with a 150mm wide detail coat of Duram 195. Cracks wider than 1.6mm and construction joints must be ground out to a minimum width of 6mm, filled with a compatible sealant over a backing rod or bond-breaker tape to maintain a 1:1 width-to-depth ratio, and then treated with a 150mm wide detail coat of membrane before full application.

Apply the membrane by brush, roller, broom, or squeegee in a minimum of two coats. Apply the second coat within 36 hours of the first to ensure strong inter-coat adhesion without repriming. If dilution is necessary due to site temperature or viscosity, thin only with Duram Solvent up to a maximum of 1 Litre per 15 Litre pail. Do not use alternative solvents, as they will cause curing failure, slow drying, gassing, or gelling.