Repair Systems — Insulation and Falls
Tapered and flat roof insulation board systems — roofs and podiums
Technical product reference for tapered insulation board systems used on roof decks and podium slabs. Covers warm roof and inverted roof assemblies, PIR vs XPS vs mineral wool selection, falls creation, vapour control layers, condensation risk, NCC Section J compliance, and Australian brand comparisons.
What are tapered insulation board systems?
Tapered (falls) insulation boards create drainage falls within the insulation layer of a warm-roof podium or roof build-up, so water runs to the outlets without a separate concrete falls screed. They range from high-performance PIR boards (Kingspan Thermataper, Recticel, Fatra, Bauder) cut to a bespoke project layout, through closed-cell XPS for moisture-resistant and inverted-roof positions, to non-combustible mineral wool where the fire engineer or NCC requires it. Selection turns on the warm-roof vs inverted position, the material for the duty, a project-specific tapered layout to achieve the fall, and the facing/compatibility with the membrane above. Confirm every value against current Australian manufacturer data.
Product Reference
Individual products — one card each — scroll to view all
Kingspan Insulation Australia
Kingspan Thermataper TT46 / TT47
PIR foil-faced tapered roof insulation
Kingspan Thermataper TT46/TT47 are PIR tapered insulation boards with composite foil facings, part of Kingspan's Therma Tapered Roofing range and listed on kingspan.com/au. TT46 is designed for mechanically fixed single-ply (PVC/FPO/TPO) warm roofs in 1:60 and 1:80 fall systems; TT47 is the constant-thickness companion board. Kingspan provides a project-specific tapered layout design service with boards labelled for placement.
Recticel (Gradient) — WPD Group
Recticel Eurothane Silver A
PIR foil-faced tapered insulation board
Recticel Eurothane Silver A is a PIR rigid foam tapered insulation board with multi-layer foil facing on both faces, used in warm flat roof assemblies to provide thermal insulation and create drainage falls without a concrete screed. Recticel's tapered division (Gradient) designs a bespoke layout plan per roof or podium showing board positions, thicknesses, ridges and valleys. In Australia it is available through WPD Group.
Fatra Australia
Fatra PIR Tapered Insulation System
PIR tapered system within complete Fatra warm roof
Fatra Australia designs and manufactures project-specific PIR tapered insulation as part of its complete warm roof system — incorporating the tapered PIR board, a FatraVap or Fatrapar vapour control layer, and the Fatrafol PVC membrane above. It is offered in fully adhered (FatraVap + Fatrabond PU adhesives + Fatrafol 807v) and mechanically fixed (Fatrapar + Fatra Pad System + Fatrafol 810v) configurations, both non-penetrative through the membrane field.
Enduroflex Australia
Enduroflex Tapered Insulation Service
Warm-roof tapered insulation design & install service (NSW)
Enduroflex provides warm-roof tapered insulation design and installation in New South Wales, with condensation risk analysis offered alongside the tapered insulation specification. Enduroflex supplies the DuO waterproofing membrane (BRANZ appraised) for exposed roof deck, podium and balcony applications and offers tapered insulation as part of a complete warm-roof package. Confirm current range and geographic reach before specifying outside NSW.
Generic (XPS)
XPS Extruded Polystyrene Board
Closed-cell moisture-resistant rigid insulation
Extruded polystyrene (XPS) is the standard insulation for inverted (protected-membrane) roofs where the board sits above the waterproofing membrane and is permanently exposed to draining water; its closed-cell structure gives low moisture absorption. In an inverted roof it is laid loose above the cured membrane and held by the ballast/pavers above. It is also used in warm-roof and podium build-ups where moisture resistance matters and as protection board.
Generic (mineral wool)
Mineral Wool Flat Roof Board
Non-combustible rigid insulation board
Mineral wool (stone wool) rigid boards are non-combustible and are the preferred or required insulation where the NCC, fire engineer or certifier specifies non-combustible construction in the roof build-up. They are used in warm-roof assemblies above the VCL and below the membrane, compatible with single-ply PVC/FPO (mechanically fixed) and compatible torch-on systems. Thermal performance is lower than PIR, so thicker board is needed for a given R-value.
Bauder
Bauder Tapered Insulation (BauderPIR FA TE)
PIR tapered insulation within Bauder warm-roof systems
Bauder offers PIR tapered insulation as part of its complete warm-roof systems, with a project-specific tapered design service to create drainage falls in the insulation layer beneath bituminous or single-ply membranes. Confirm the facing type, membrane compatibility and current Australian distribution with Bauder before specifying.
System Comparison
Tapered insulation board systems — confirm all selections against the current manufacturer TDS before specifying.
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DO NOT USE PIR INSULATION IN AN INVERTED ROOF ASSEMBLY ABOVE THE WATERPROOFING MEMBRANE
PIR (polyisocyanurate) insulation is designed for warm roof assemblies where it is positioned below the waterproofing membrane, protected from moisture by the membrane and VCL below. PIR is not suitable for inverted roof (protected membrane) assemblies where the insulation is positioned above the waterproofing membrane and is exposed to moisture draining through the ballast, paver, or growing medium layers above. In permanently wet above-membrane conditions, PIR absorbs moisture over time, degrading thermal performance and potentially causing structural issues. The correct insulation for inverted roof assemblies above the waterproofing membrane is XPS — which has a closed-cell structure that resists moisture absorption. Do not substitute PIR for XPS in an inverted roof assembly without specific manufacturer and building physicist confirmation.
A VAPOUR CONTROL LAYER IS MANDATORY IN WARM ROOF ASSEMBLIES OVER HABITABLE SPACES — OMISSION CAUSES INTERSTITIAL CONDENSATION
In a warm roof assembly over a habitable space (occupied apartments, car parks with habitable floors above), warm moist air from below will rise through the structural deck and condense within the insulation layer if a vapour control layer (VCL) is not installed between the deck and the insulation. Interstitial condensation within the insulation degrades thermal performance, causes moisture damage to the structure, and may result in mould growth on the underside of the deck. A VCL — typically a self-adhesive bituminous sheet, reinforced polyethylene, or aluminium-foil-faced board — must be installed on the warm side of the insulation (between the deck and the insulation) in all warm roof assemblies over habitable spaces. Confirm the VCL specification with a building physicist or the insulation system designer before specifying.
TAPERED INSULATION IS A BESPOKE MANUFACTURED PRODUCT — THE LAYOUT MUST BE DESIGNED BEFORE ORDERING
Tapered insulation boards are not stocked items that can be ordered off the shelf and cut on site. The taper profile, board thickness at each position, fall direction, ridges, valleys, and hips in the insulation layout must be designed by the insulation manufacturer or a roof drainage engineer based on the roof or podium geometry, outlet positions, and required fall. The designed layout is then used to manufacture boards with the correct taper for each board position, labelled for site placement. This design and manufacture process takes time — confirm lead times with the supplier well before the project installation programme. Do not order tapered insulation without a confirmed layout design — once boards are cut to a specific layout they cannot be repositioned to a different plan.
CONFIRM NCC SECTION J REQUIREMENTS BEFORE SPECIFYING INSULATION THICKNESS
NCC Section J sets minimum thermal performance (R-value) requirements for roof and podium deck assemblies in Class 2 strata buildings. In remediation projects, confirm with the building certifier and a thermal performance assessor whether the remediation scope triggers a Section J upgrade requirement and what R-value must be achieved. The required R-value determines the insulation type and minimum thickness — do not assume a standard insulation thickness will meet Section J requirements without a thermal performance calculation. Different insulation materials (PIR, XPS, mineral wool) achieve different R-values at the same thickness — confirm the material and thickness against the calculated required R-value before specifying.
Disclaimer
This page provides general technical information only. Final product selection must be confirmed against the current manufacturer technical data sheet, project specification, roof assembly type (warm or inverted), structural loading, compressive strength requirements, NCC Section J thermal performance requirements, vapour control layer specification, condensation risk analysis, drainage design, fire performance requirements, and building certifier requirements. Tapered insulation requires bespoke project-specific design before manufacture and ordering — confirm lead times with the supplier before committing to programme dates. Do not rely on this reference as a substitute for professional building physicist, thermal performance assessor, structural engineer, or waterproofing consultant advice.