For inverted roof waterproofing.


Inverted roof waterproofing system with ballast.


  • 20–40 mm washed ballast or paving slabs on supports.
  • Water Flow Reducing Layer (WCL): Filter layer/ water control layer. High performance and thermally bonded.
  • Enertherm XPS insulation: Lightweight, lap jointed, rigid extruded polystyrene (XPS) boa
  • Armourplan P waterproof covering: UV stable waterproofing membrane with high mechanical properties.
  • Spectratex Separation Layer: Polyester geotextile isolation and protection fleece.
  • Screed and concrete deck (by others).


For inverted roof waterproofing.

General information

Uniclass 2015

Ss_30_40_30_79 Single layer sheet inverted roof covering systemsPrimary


J42/120 Inverted roof covering

Specification data - Single layer sheet inverted roof covering systems

Product Reference

Inverted Armourplan P on 300 g/m² Fleece, with Ballast, Water Flow Reducing Layer and Enertherm XPS

Separating layer



Spectratex Separation Layer – Polyester geotextile


300 g/m²

Roll size: 50 x 2 m (l x w). Standard.

500 g/m²

Roll size: 25 x 2 m (l x w).

800 g/m²

Roll size: 25 x 2 m (l x w).

Waterproof covering



Armourplan P


1.06 m

1.5 m

2.12 m



Mid grey




Enertherm XPS


Insert requirement, available 50–245 mm.

Filter layer

Water Flow Reducing Layer (WCL)


20–40 mm washed ballast

– Rounded washed river stones sourced from the Moray Firth.

Paving slabs on supports

Standard product features

Water Flow Reducing Layer (WCL):

  • Material: Tri-laminate of polypropylene; spun bonded outer layers and microporous inner layer.
  • Roll size (l x w): 100 x 1.5 m.
  • Weight: 95g/m²
  • Tensile strength (to BS EN 12311-1): 185 N/50 mm/ 130 N/50 mm (MD/ TD).
  • Nail tear resistance (200 mm folded): To BS EN 12310: 55 N/200 mm; to BS EN 13859: 65 N/200 mm.
  • Water resistance (to BS EN 20811) 1.5 m of water head.
  • Water vapour transmission: 1200 g/m².
  • UV stability under constant exposure (to BS EN 1297): Up to four months.
  • Laps: 300 mm.

Armourplan P:

  • Material: Plasticized polyvinyl chloride (PVC-P) with polyester knitted fabric.
  • Thickness: 1.2 mm.
  • Length: 20 m.

Enertherm XPS:

  • Material: Rigid extruded polystyrene (XPS).
  • Size (l x w): 1250 x 600 mm.
  • Edges: 15 mm rebated on all four sides.
  • Overlap: 15 mm.
  • Nominal density: 32 kg/m³.
  • Thermal conduction coefficient: <100 mm thickness: 0.035 W/mK; ≥100 mm thickness: 0.034 W/mK.
  • U-value: Dependent on thickness, consult manufacturer's literature for information.
  • Compressive strength: 300 kPa (at 10% compression).
  • Water vapour resistance (to BS EN 12086): 625 MBs/g.
  • Moisture absorption (to BS EN 12087): 0.6% by volume.
  • Zero ozone depletion potential (ODP) and a global warming potential (GWP) of <5.
  • Maximum service temperature: 70°C.

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