DriStud RU24 Roof Underlay

Vapour Permeable Synthetic Self Support Roof Underlay (Non Fire Retardant)

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DriStud RU24 is non-fire retardant self-supporting black faced synthetic roofing underlay.

It is a tri-laminate consisting of engineered synthetic materials and it is water resistant and vapour permeable. DriStud RU24 must not be installed where fire retardant roof underlay is specified.

It is intended for use on new and existing buildings in wind zones up to and including ‘Extra High’, as defined in NZS 3604:2011.

CodeMark Certified


  • CodeMark™ Certified
  • Self-supporting
  • Can be installed over timber and steel roof framing
  • Breathable & Absorbent
  • UV exposure: 10 days
  • Direct fix with absorbent and non-absorbent cladding including metal
  • Low cost synthetic underlay with FR Index of 9 (Non Fire Retardant)
  • Easier and Quicker to install with 150mm laplines
Weight (m²)170 ±5 g/m2
Flammability indexAS1530.2-19939
Fire RetardantNo
Water Vapour ResistanceASTM E96 Procedure B0.303 MNs/g; Pass
AbsorbancyAS/NZS 4201: Part 6Requirement ≥150 g/m²; Pass
Air ResistanceBS ISO 5636-5:2003≥0.1 MN s/m³; Pass
Air BarrierYes
Water ResistanceAS/NZS 4201.4:1994≥100mm H₂O; Pass
Resistance to UV exposureASTM G15510 days
Durability (years)50
SupportedSelf Supporting
Roof Pitch˃3°


Overlaps / support
DriStud roofing underlays must be installed with all writing and imagery facing out and with as minimal a number of overlaps as possible. Where overlaps are unavoidable a lap of 150 mm minimum must be used. DriStud RU24 must not span more than 1.2 m between adjacent supports.

RU24 is affected by exposure to UV radiation and should not be installed where it is exposed to prolonged sunlight.

If installing on a roof with a pitch greater than 10° then DriStud roofing underlays may be installed either horizontally or vertically.

If the roofs pitch is 10° or less it is recommended to be run horizontally with the higher layers sitting on top of the lower layers. It can be installed without supporting netting for horizontal installation.

When it is not practical to place underlay horizontally, DriStud RU24 can be run vertically on a minimum side lap of 150 mm. Underlays must be pulled taut to ensure there are no sagging. If any doubt, it is recommended the joins are taped.

The netting and underlays must be installed flat and taut to ensure condensation will drain to the gutter. If any doubts vertical laps are recommended to be sealed with 75mm DriStud Cool window flashing tape or DriStud Joining Tape to ensure it.

DriStud RU24 must have support on netting or safety mesh if used: * On roof pitches less than 10° when installed vertically * If support spacing > 1200mm

When DriStud roofing underlays are being used in conjunction with masonry tiles, anti-ponding boards should be used at the lower edges of the tiles.

Available Sizes


1250mm x 40.0m (50m²)
1500mm x 40.0m (60m²)
2200mm x 50.0m (110m²)