Repair Systems — 01
TPO/FPO sheet membrane systems — exposed roofs and decks
Technical product reference for TPO and FPO heat-weldable sheet membrane systems used on exposed roof decks, balconies, and utility platforms in Australian Class 2 strata apartment buildings. Covers product type classification, installation method selection (fully bonded, loose-laid), substrate compatibility, heat-welding requirements, trafficability, and AS 4654.1 compliance.
What are TPO / FPO exposed sheet membranes?
TPO / FPO membranes are thermoplastic-polyolefin single-ply sheets, heat-welded at the laps, designed for direct exposure on roofs and decks with high resistance to heat, UV and ozone ageing. They are mechanically fixed or adhered and finished exposed (no tile or paver cover). Selection turns on thickness/grade, the fixing method and wind-uplift design, and the Class 2 (NCC) test evidence to AS 4654.1.
Class 2 (NCC) — roofs & podiums: specify only a sheet with current Australian test certification (see the “Class 2 / NCC tested” field on each card). A product with no value is unverified.
Product Reference
Individual products — one card each — scroll to view all
ARDEX Australia
ARDEX WPM 715
FPO/TPO heat-weldable single-ply (WeldTec) — exposed
ARDEX WPM 715 (WeldTec) is a 1.5 mm FPO/TPO heat-weldable single-ply membrane for exposed decks and rooftops, with excellent resistance to ageing from heat, sunlight and ozone and excellent gas impermeability. BRANZ tested to AS 4654.1, wind-uplift certified, and AS/NZS 4020 potable-water compliant. Supplied 1.4 m × 20 m rolls.
ARDEX Australia
ARDEX WPM 717
FPO/TPO heat-weldable single-ply (WeldTec) — exposed
ARDEX WPM 717 (WeldTec) is an FPO/TPO heat-weldable single-ply membrane for exposed decks and rooftops — the heavier-grade companion to WPM 715. Confirm the exact thickness/grade and its BRANZ AS 4654.1 test report with the current Ardex Australia TDS.
System Comparison
TPO / FPO exposed sheet membranes — confirm all selections against the current manufacturer TDS before specifying.
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Do not confuse TPO/FPO exposed membranes with:
- Single-ply PVC ballasted membranes (Wolfin IB, Cosmofin, Fatrafol 810v, Sarnafil G 410-L) — PVC with plasticiser, covered by ballast (pebble or pavers), not UV-exposed — separate product category on this site
- Liquid-applied polyurethane and hybrid membranes (ARDEX WPM 157, Sika Sikalastic-487) — applied by roller or brush as a liquid, not a factory-manufactured sheet product
- Torch-on modified bitumen sheet membranes (SBS and APP bitumen) — bituminous chemistry, heat-applied by gas torch, not TPO — different material, different installation, different performance profile
- HDPE sheet membrane systems — high-density polyethylene, different chemistry, typically used below-slab, in planter boxes, or on podium structures with overburden — not UV-exposed
- Cementitious flexible membranes (ARDEX 8+9, Mapei Mapelastic) — two-part cement-based systems applied by brush, not sheet systems
ARDEX WA 98 contact adhesive must not be applied to heat-weld seam zones
ARDEX WA 98 is the solvent-based contact adhesive used to bond WPM 715 to the substrate in fully bonded installations. A critical installation rule applies: WA 98 must not be applied to any area of the membrane or substrate where adjacent sheets will be seam-welded. Contact adhesive contamination prevents the hot-air welding equipment from forming a correct seam — the adhesive residue degrades the weld, and the seam will fail. Plan adhesive application zones carefully before installation to ensure all seam overlap areas (minimum 40mm from the sheet edge on both sheets) remain adhesive-free. Mark seam lines on the substrate before applying WA 98.
All seams and laps must be heat-welded using an approved hot-air welding unit — no cold bonding at seams
ARDEX WeldTec TPO membranes are thermoplastic systems — seams and laps are formed by heat-welding with an approved hot-air welding machine, not by cold bonding with adhesive. Cold-bonded seams are not acceptable and will fail over time. Minimum 40mm overlap is required at all side and end laps before welding. The membrane surface must be solvent-wiped before welding to remove contamination — unwashed membrane surface will not weld correctly and the seam will delaminate. ARDEX requires installation to be carried out by trained and approved applicators using an approved welding unit — confirm accreditation requirements with ARDEX Australia before commencing work.
Sika Sarnafil AT — FPO mechanically fixed membrane — confirm Australian availability
Sika Sarnafil AT is a confirmed FPO (flexible polyolefin) single-ply membrane available internationally in AT-15, AT-18, and AT-25 variants, designed for mechanically fixed exposed roof applications with UV resistance. It is confirmed in Sika UK and Sika global documentation but was not confirmed on the Australian Sika website (aus.sika.com) at the time of publication. If Sarnafil AT is being considered for an Australian Class 2 strata roof project, confirm current Australian product availability, accredited applicator access, and current technical specifications directly with Sika Australia at aus.sika.com or by contacting Sika Australia technical on 1300 22 33 48. Do not specify based on international documentation alone.
Disclaimer
This page provides general technical information only. Final product selection must be confirmed against the current manufacturer technical data sheet, project specification, substrate moisture content, installation method suitability (fully bonded vs loose-laid), AS 4654.1 compliance status, wind uplift requirements, and NCC requirements. Substrate moisture content must be within ARDEX limits before WPM 715 or WPM 717 installation — confirm with ARDEX Australia. WA 98 contact adhesive must not be applied to areas where heat-welded seams will be located. All seams require heat welding with an approved hot-air welding unit — minimum 40mm overlap — solvent-wiped before welding. Maintenance inspection obligations apply to exposed membranes per ARDEX TB272. Do not rely on this reference as a substitute for professional waterproofing consultant advice.
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