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DriStud Synthetic Roofing Underlays Engineered for All NZ Weather Conditions

Specifically designed and tested to the NZ Building Code standard, DriStud Synthetic Roofing Underlays are weathertight and are an essential element within the moisture management system within roofs.

TCL Hunt offers four different types of DriStud Synthetic Roofing Underlay — two fire retardant and two non-fire retardant.

Where fire retardant roofing underlays are specified, either FRU 38 (Self Support) or FRU 36 (Heavy Weight) are recommended.

DriStud non-fire retardant roofing underlays RU 24 (Self Support) and RU 22 (Heavy Weight) are economical and are a great alternative to bituminous based roofing underlays — recommended when fire retardancy is not required.

DriStud Roofing Underlay Property Chart
  FRU 38 FRU 36 RU 24 RU 22
CodeMark Certified
Heavy Weight    
Fire Retardant    
FR Index 1 1 9 17
Durability: 50 years (B2.3.1 (a))
Wind Zones up to and including 'Extra High' (NZS 3604:2011)
Can be installed over timber and steel roof framing
Can be direct fixed behind all claddings
Can be used for skillion roofs, commercial and industrial roofing

DriStud Synthetic Roofing Underlays meet NZ Building Codes B2, E2, C3 and all roofing underlay requirements as referenced in MRM Code of Practice:-

  1. To provide a temporary means for the accumulation of condensation by absorption
  2. To provide a permeable membrane to allow the passage of water vapour
  3. To prevent the ingress of external moisture into roof or wall cavities
  4. To provide a separation barrier between the metal cladding and copper preservative treated timber.
 Property Parameters for FRU 38 and FRU 36 (Tested according to NZ Standard 2295:2006):-
  1. Water Vapour Resistance 2. Absorbency 3. Water Resistance 4. Flammability
Test Method ASTM E 96 Procedure B AS/NZS 4201: Part 6 AS/NZS 4201.4:1994 AS 1530.2:1993
Roofing Underlay Requirements ≤ 7MNs/g ≥ 150 g/m² ≥ 100mm head water ≤ Index 5
FRU 38 Fire Retardant, Self Support Roofing Underlay Pass 225 g/m² Pass Index 1
FRU 36 Fire Retardant, Heavy Weight Roofing Underlay Pass ≥ 160g/m² Pass  Index 1

DriStud's synthetic roofing underlays are intended for use on new and/or existing buildings with steel or timber framing. The roofing underlay must be installed according to and comply with the New Zealand Building Code.

View more information on DriSpace, including contact details.
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