DriStud FRU 38 is a white synthetic tri-laminate roofing underlay that is water resistant, vapour permeable and fire retardant. The FRU 38 is a self-supporting, roof underlay.
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 38 is a Heavier grammage self-support roof underlay, whereas DriStud FRU 36 is a lighter grammage self-support roof underlay.
- CodeMark™ Certified
- Self Supporting
- Can be installed over timber and steel roof framing
- Fire Retardant (FR Index: 1)
- Breathable & Absorbent
- Durability: 50 years
- Direct fix with absorbent and non-absorbent cladding including metal cladding
||220 ±5 g/m2
|Roll Sizes (m²)
||1250mm x 40m (50m²)
|Water Vapour Resistance
||ASTM E96 Procedure B
||Requirement ≤7 MNs/g; Pass
||AS/NZS 4201: Part 6
||Requirement ≥150 g/m²; Pass
||BS ISO 5636-5:2003
||≥0.1 MN s/m³; Pass
||≥100mm H₂O; Pass
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 FRU 38 must not span more than 1.2 m between adjacent supports.
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 DriStud roofing underlays is recommended to be run horizontally with the higher layers sitting on top of the lower layers. When it is not practical to place underlay horizontally, DriStud FRU 38 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 tapes to ensure it.
DriStud FRU 38 must have support on netting or safety mesh if used:
- Under dark coloured metal cladding
- On roof pitches less than 10°
- If support spacing > 1100mm
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.
TCL Hunt Ltd warrants that all DriStud roofing underlays will be free from manufacturing defects. Upon receiving of DriStud roofing underlays, it is recommended that a visual check is made. Where defects are observed, these will be replaced at the discretion of TCL Hunt, provided that they are returned to point of purchase.
If installed in accordance with TCL Hunt installation requirements, TCL Hunt warrants that DriStud roofing underlays will comply with all relevant provisions of the NZ Building Code. DriStud roofing underlays will have a serviceability equal to that of the roof cladding provided that:
- the balance of the external wall is installed in accordance with the NZ Building Code, and,
- all necessary maintenance is undertaken in respect of the external wall system.
Please refer to DriStud website www.dristud.co.nz for more information on warranty and disclaimer.