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Metdek 855 Deep Trough Roofing and Wall Cladding System

Metdek 855 Roofing and External Wall Cladding system is comprised of a long run steel sheet with a 60mm deep trough profile, along with associated design and installation information. 

Metalcraft fabricates the Metdek 855 sheets from steel manufactured by New Zealand Steel. This steel is supplied with different protective coatings which are designed to withstand conditions in specific New Zealand Corrosion Zones. 

Key Features
  • 60mm deep trough profile
  • Sheets can be run onsite to any length
  • Ideal for low pitch roofs (3° minimum)
  • Suitable for roofing, and as vertical cladding
  • Concealed clip system
  • Metdek 855 is available in Colorsteel® Endura®, Galvsteel®, Colorsteel® Maxx®, and Zincalume®
  • Metdek 855 is available in the following sizes:
    • Thicknesses: 0.4mm, 0.48 and 0.55mm
    • Width: Cover = 855mm, Sheet = 925mm
Scope of Use

Metalcraft Roofing supply the Metdek 500 system as a external vertical wall cladding and on roofs with a defined pitch of a minimum of 3 degrees, for use on commercial and residential buildings within the following scope:


  • In wind zones:
  • Up to and including Extra High as defined by NZS-3604:2011
  • Subject to specific engineering, if the engineer has satisfied themselves that the product, pitch and fixings will meet the conditions
  • In all climate zones as defined by NZS-3604:2011, subject to the limitations set out below
  • On buildings located within 1m of the relevant boundary, in respect of fire spread only


  • On new buildings that have been designed and constructed to comply with the NZ Building Code (NZBC) using timber or steel framing
  • On existing buildings using timber and steel framing where the designer and installer have satisfied themselves that the building is suitable for the intended building work
  • In conjunction with a vapour permeable building wrap that has a permeability of 36g/m2/day of a vapour resistance of no more than 500MNs/g
  • Can be used in conjunction with a potable water collection system
Limitations on Use


  • Metdek 855 may be used as a roof cladding system in exposure zones B, C & D. For use in 'Microclimatic considerations,' (as defined in Sec 4.2.4) refer to Metalcraft Roofing
  • Metdek 855 may be used as a wall cladding system in exposure zones B & C. Where Metdek 855 is to be used as a wall cladding in exposure Zone D, then only Colorsteel® Endura® or Colorsteel® Maxx® may be used


  • Where Metdek 855 is used in an insulated building in conjunction with steel framing, a thermal break is required. This will depend on the location of the insulation layer. Timber thermal breaks are recommended
  • Contact with other materials must be in accordance with Table 21 (E2/AS1), or compatible with the The New Zealand Metal Roofing Manufacturers Association Inc (NZMRM) Code Of  Practice
  • Building height and design wind speed is limited by the Metdek 855 design load span tables
  • Where it is used as a roof cladding, Metdeck 855 sheet lengths of ≤40m must be installed on a roof with a minimum pitch of 3°. Metdeck 500 sheet lengths of > 40m but ≤ 60m must be installed on a roof with a minimum pitch of 4°
  • Metdek 855 can be used in conjunction with a potable water collection system
  • When used as a wall cladding, Metdek 855 must be installed in conjunction with a drained cavity
3° Minimum Roof Pitch Required
NZS 3604 Corrosion Zone D suitable
Corrosion Exposure Zone D
NZS 3604 Wind Zone Extra High suitable
Extra High Wind Zone
NZS 3604 Wind Zone Specific Design suitable
Specific Design Wind Zone
Statement of Building Code Compliance

If designed, installed and maintained in accordance with all Metalcraft Roofing requirements, the Metdek 855 Roofing and External Cladding system will comply with or contribute to compliance with the following provisions of the NZ Building Code:

  • B1 Structure: B1.3.1, B1.3.2, B1.3.3 (a, b, c, d, g, i)
  • B2 Durability: B2.3.1 (b)
  • C3 Fire Affecting Areas Beyond the Fire Source: C3.4(a), C3.5, C3.7 (a)
  • E2 External Moisture: E2.3.1, E2.3.2, E2.3.7 (a-c)
  • F2 Hazardous Building Materials: F2.3.1

See product technical statement for full information.

Other Performance Attributes
  • Metdek 855 Roofing and External Cladding system will not contaminate potable water — AS/NZS 4020:2005
B1 Structure compliant
B2 Durability compliant
C Protection from Fire compliant
Protection from Fire
E2 External Moisture compliant
External Moisture
F2 Hazardous Building Materials compliant
Hazardous Building Materials
Loadspan Graph and Fixing Table
Product Technical Statement


Fire Testing Document
Environmental Category Brochure
Colour Range
Additional Information
CAD/PDF Details
Commercial Roof Details
Commercial Roof Details DWG
Commercial Roof Details DXF
Commercial Vertical Cladding Details
Commercial Vertical Cladding Details DWG
Commercial Vertical Cladding Details DXF
Commercial Roof Details RVT
Commercial Vertical Cladding Details RVT

Metalcraft Roofing are a privately owned building product rollformer and installer with an extensive range of longrun roofing profiles, lightweight metal tiles and rainwater system solutions.

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