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VENT Skillion Mono Pitch Roof Ventilation System

Through the design and installation of specific product combinations, an unimpeded passive ventilation system is created.

For a Skillion Mono Pitch Roof (any degree pitch) the following product combinations are recommended:

  • G2500N VENT Over Fascia Vent (which allows calculated airflow into the roof cavity)
  • VB20 VENT Vented Batten performs two functions:
    • a) Placed on top of the purlins the VENT Vented Batten ensures unimpeded airflow above the purlin. (as recommended by BRANZ (Build 155 "Vents in skillion roofs"))
    • b) allows the naturally warm moist air to escape through the barge and at the same time creates negative pressure to draw air through the roof cavity.

A Skillion Pitched Roof of any degree pitch requires continuous airflow of 25.000mm² per lin/m at eaves level, unimpeded airflow through the roof cavity and ventilation at the ridge. Ventilating the roof cavity in this way will ensure that internal moisture is greatly reduced in the roof cavity which safeguards the roof from damp, mould and structural decay.

Key Features
  • Creates negative pressure to ensure air flows in and out of the roof cavity 
  • Eradicates condensation in the roof cavity
  • Allows calculated airflow into the roof space
  • Allows moisture escape
  • Reduces the temperature above the thermal envelope of the building
  • Ensures unimpeded airflow through the roof cavity
  • Ventilates above and below the purlin (as recommended by BRANZ)
  • Reduces margin for error during insulation installation process
  • Prevents ingress of nesting insects into the roof cavity
  • Easy to install
Scope of Use

These passive ventilation systems can be applied to all building types in all areas.

VENT's passive ventilation roofing systems allow a calculated amount of fresh air to enter the roof cavity.  

Vent passive ventilation systems can be used with roof types such as long run, pressed metal, asphalt shingle and concrete tiles.

The system also works well with mechanical ventilation systems that are not externally ventilated i.e they do not ventilate from outside the building but from inside the roof cavity.

Limitations on Use

VENT's passive ventilation roofing systems and products focus on the ventilation of roof spaces only. 


Statement of Building Code Compliance

VENT's Passive Roof Ventilation Products comply with the following provisions of the NZ Building Code:

  • B1.3.1, B1.3.2
  • B1.3.3 (a)
  • B1.3.4 (a, b, c, d, e)
  • B2.3.1 (a)
  • B2.3.2 (a)

Evidence: All products are manufactured by Manthorpe Building Products Ltd (UK) who are ISO 9001 accredited by SGS Certificate # GB12/84769, certified since 2011.

In-Service History

Passive Ventilation has been used in Canada, America, the United Kingdom and Europe for almost four decades. By introducing passive ventilation into roofs these countries have significantly reduced internal moisture and prevented what was called 'sick home syndrome'.

More recently in New Zealand, since changes to E3:AS1 1.1.4.b of the New Zealand Building Code in 2014, passive ventilation has become more widely understood and the need to ventilate the uninhabited spaces in a building has been more widely acknowledged. Industry experts BRANZ have endorsed passive ventilation as a necessity in skillion roof types and have recommended that all roof types are passively ventilated as redundancy to eradicate internal moisture.

The NZMRM is currently revising the Metal Roofing Code of Practice to incorporate ventilation into certain roof design and strongly recommending passive ventilation in all metal roof types.  

Since the amendment of E3:AS1 hundreds of New Zealand buildings have incorporated passive ventilation into building design and application, These buildings include MOE school Reroof projects, residential new build and renovations and commercial projects.

Product Technical Statement


Passive Ventilation System: Skillion Mono Roof <15°


BRANZ Appraisal 979


Maintenance and Warranty




Product Information Setting Out: G2500N, G1200N
Video: Why Is Passive Roof Ventilation Necessary


CAD/PDF Details
VENT Over Fascia Vent G2500N 15 Degrees and Skillion Roofs
VENT Over Fascia Vent G2500N Under 15 Degrees and Skillion Roofs No Eaves
Full Set of drawings with Final Extra Batten

Full Set of drawings with Final Extra Batten


Full Set of Roof Drawings

Full Set of Roof Drawings


VENT provide complete passive ventilation systems that ensure healthy homes free from internal moisture and condensation.

Product Enquiries

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