DriStud FRU36 Roof Underlay

150gsm Fire Retardant Vapour Permeable Synthetic Self-Support Roof Underlay

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Product Overview

DriStud FRU 36 is white synthetic tri-laminate roofing underlays that are water resistant, vapour permeable and fire retardant. The FRU 36 is a self support roof underlay however FRU 36 can be used for both self support and heavy weight applications. 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.

DriStud FRU 36 is a lighter grammage self-support roof underlay, whereas DriStud FRU 38 is heavier grammage self-support roof underlay.

Technical Properties

PropertyStandardValue
Weight150 ±5 g/m2
Roll Sizes (m²)1350mm x 56m (75m²), 2700mm x 37.04m (100m²)
Flammability indexAS1530.2-19931
Fire RetardantYes
Water Vapour ResistanceASTM E96 Procedure BRequirement ≤7 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°

Features

  • CodeMark™ Certified
  • Self Supporting
  • Can be installed over timber and steel roof framing
  • Fire Retardant
  • Breathable & Absorbent
  • UV exposure: 10 days
  • Durability: 50 years
  • Direct fix with absorbent and non-absorbent cladding including metal cladding
  • DriStud FRU36 can be used to line roof, wall and ceiling.
  • Roll sizes: 1350mm x 56m (75m²), 2700mm x 37.04m (100m²)
  • DriStud FRU36 can be used to line roof, wall and ceiling.

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 FRU36 must not span more than 1.2 m between adjacent supports.

Installation

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 FRU36 can be run vertically on a minimum side lap of 150 mm. Self-support roof underlays must be installed on supporting netting or equivalent system.

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 FRU36 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.