Repair Systems — 01
Vapour Control Layers — Warm Roof
Technical product reference for polyethylene and foil-faced vapour control layer (VCL) membranes installed below insulation in warm-roof balcony and podium assemblies to prevent interstitial condensation in Australian Class 2 strata apartment buildings.
What are vapour control layers (warm roof)?
A vapour control layer (VCL) sits on the warm side of the insulation in a warm-roof balcony/podium build-up to limit water vapour driving into the assembly and condensing within it. VCLs range from fixed high-resistance poly/foil barriers to humidity-variable ('intelligent') membranes that also allow seasonal inward drying, and reflective metallised grades that add radiant-heat control. A VCL is not a waterproofing membrane and is the opposite role to a vapour-permeable breather — selection turns on vapour resistance for the assembly, airtight taped detailing, and a dew-point/condensation analysis.
Product Reference
Individual products — one card each — scroll to view all
Kingspan Insulation Australia
Kingspan Nilvent
Breathable / non-tenting waterproof underlay membrane
Kingspan Nilvent is a breathable (vapour-permeable), waterproof, airtight, non-tenting membrane for unventilated pitched roofs and timber-frame walls — it lets the assembly dry outward rather than acting as a high-resistance vapour barrier.
DuPont / Tyvek
DuPont Tyvek AirGuard Reflective
Metallised airtight vapour control layer (low-emissivity)
DuPont Tyvek AirGuard Reflective is a robust, 100% airtight vapour control layer with a metallised low-emissivity surface that reflects up to 95% of radiant heat, installed on the warm side of the insulation in roofs, ceilings and walls. Seal all laps, penetrations and cuts with Tyvek Metallised Tape.
Pro Clima / Rothoblaas
Pro Clima DB+
Humidity-variable (intelligent) vapour control membrane
Pro Clima DB+ is a humidity-variable ('intelligent') vapour control membrane whose vapour resistance changes with humidity — higher in winter to limit vapour drive, more open in summer to allow inward drying — installed on the warm side of the insulation in roofs and walls. Confirm the current Australian distributor and availability.
Generic
Heavy-Duty Polyethylene / Foil VCL
Polyethylene / foil vapour barrier (commodity)
A heavy-duty polyethylene or foil-faced vapour barrier is a low-cost, high-resistance (fixed) vapour control layer placed on the warm side of the insulation in roof/wall build-ups. Confirm the specific product, thickness and vapour-resistance class, and seal all laps/penetrations for continuity.
System Comparison
Vapour control layers — confirm all selections against the current manufacturer TDS before specifying.
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Disclaimer
Information is general only. VCL specification must be confirmed by condensation analysis (Glaser method or dynamic hygrothermal simulation) for the specific warm-roof assembly, climate zone, and building use. Product selection must be confirmed against AS/NZS 4200, NCC energy efficiency requirements, and the current manufacturer technical data sheet. A VCL is not a substitute for correct waterproofing membrane detailing. Do not rely on this reference as a substitute for professional engineering, building physics, or waterproofing consultant advice.