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OMEGA MONOTOP 330 SK DUO Roof Underlay

OMEGA MONOTOP 330 SK DUO Roof Underlay
Vapour permeable roof underlay for roofs where there is an increased need for raintightness in accordance with ÖNORM B 4119. Use for roof pitches starting from 5°.
  • outdoor exposure up to 6 months
  • anti-slip and stable with two integrated adhesive stripes
  • easier to process
  • no wave formation

Available dimensions

Article number Type Roll width Roll length Rolls / Pallet Total area Inquiry List
2OM330P SK DUO 1.5 m 25 m 24 rolls 900 m²

Field of application

  • for vented pitched roofs
  • for roofs with increased need for rain-tightness
  • for installation directly on thermal insulation / wood sheathing


  • rain-tight
  • wind-tight
  • six months uv-resistance
  • anti-glare
  • water-tight
  • easily cut

Product data

is a vapour permeable roof underlay for installation directly on the thermal insulation or the wood sheathing. The underlay can be welded on the joints. The roof underlay is suitable for roofs with increased need for rain-tightness (because of small roof pitch for example). According to German classification it is UDB-A and USB-A. The membrane guarantees extreme resistance against wind-driven rain while humidity in form of vapour still can pass the construction.
Material composition
Monolithic membrane with PES fleece on both sides and two two-way acrylate adhesive strips
1 mm
Dark grey
330 g/m²
0.15 m
(+0,05 / -0,08)
Temperature resistance
-40 °C
Temperature resistance
100 °C
6 months
Resistance to water flow
Resistance to water flow
EN 1928
Elongation - lengthwise
30 % (-10 / +20)
Elongation - crosswise
50 % (±20)
EN 12311-1
Tensile strength - lengthwise
550 (-60 / +50) N / 50mm
Tensile strength - crosswise
350 (-60 / +50) N / 50mm
Tensile strength
EN 12311 - 1
Tear propagation resistance - lengthwise
250 ( -50 / +30) N
Tear propagation resistance - crosswise
250 ( -50 / +30) N
Tear propagation resistance
EN 12310-1
Cool and dry
Fire performance
Fire performance
EN 13501-1 / EN 11925-0

Processing guideline

(1) UNDERLAY (unsupported)

OMEGA roof Underlay is nailed parallel to the eaves with a slight drape and laid and mechanically fixed above the rafters. Vertical overlaps/joins must always lie on a rafter.
All overlaps must be bonded with OMEGA QUILLI Sealing Compound. Horizontal underlay panels can be joined using SK DUO adhesion as provided or with OMEGA QUILLI Sealing Compound (no pressure need be applied).
(1) UNDERLAY (unsupported)

(2) UNDERLAY (supported)

OMEGA roof underlay is laid on sheathing parallel to the eaves. The blankets are fixed with concealed nails spaced at 10 cm at the ridge-side edges (marks at edge). All overlaps/joins must be bonded with OMEGA QUILLI Sealing Compound (without applying pressure) or the integrated adhesive strips (applying adequate pressure). For the raintight version (temporary cover) a nail-seal under the counter batten (OMEGA QUILLI Sealing Compound or OMEGA NDB Nail Sealing Tape ) is necessary. The single-sided nail-seal tape must be attached to the roof underlay directly beneath the counter batten!
(2) UNDERLAY (supported)


We recommend an eaves construction with drainage below the gutter so that snowmelt build-up can easily drain off. We recommend the use of a metal sheet to drain off water.


The ridge area is closed directly when covered with OMEGA roof underlay. This provides immediate protection against water penetration. In non-insulated lofts and/or ventilated interior insulation the ridge formation must be made open: the blankets end 3 cm before the ridge apex, counter battens are mounted and a
50 cm wide strip of OMEGA roof underlay must be attached over the roof apex.


The first step in valley formation is to lay a continuous valley blanket.


Sections cut out for roof penetrations (extractor pipes, roof windows, chimneys, etc.) should be kept as small as possible and the ends of the sheets must be fixed so that no rain or snow can penetrate. To achieve a perfect seal the suitable adhesive technology by ISOCELL GmbH & Co KG must be used.
Make sure that the substrate is clean! The manufacturer can accept no liability for mechanical damage. The applicable regulations and guidelines (e.g. of the ZVDH (Central Association of German Roofers) for Germany, Austrian Standard, ÖNORM B 4119, for Austria, ...) must be observed!
The roof underlay does not replace roof covering. The roof must be covered during the period of the specified weathering time. Early covering has a positive effect on the resistance to ageing.