You are using an outdated browser version not supported by this website.
Click here to upgrade your browser

VENT Retro Cold Roof 15°-30° Ventilation System
Description

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

For a Retro Cold Roof Pitch of 15°-30° the following product combinations are recommended:

  • G700 VENT Circular Soffit Vent 
  • EV25 VENT Eaves Vent 

A RETRO Cold Roof Pitch of 15°-30° degrees requires continuous cross airflow of 10.000mm² per lin/m at eaves level. 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
  • 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
  • Protects the insulation from moisture transfer and wind movement
  • Ensures 25mm gap between insulation and roofing underlay
  • 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.  

As part of the VENT passive ventilation roofing system, the VENT Eaves Vent (EV25)  ensures a 25mm gap is maintained between rigid or flexible roof underlays and insulation to avoid moisture transfer and air disturbance, to meet the requirements of most insulation products.

Whilst recommended for RETRO fit projects this product combination can be applied to NEW build projects as well. 

The system 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. 

Documents
Data Sheet: G700

2021

Appraisal, Accreditation, Certification and Testing

2021

Accreditation
Brochure

2021

Video: Why Is Passive Roof Ventilation Necessary

2021

CAD/PDF Details
VENT Circular Soffit Vent - G700
Full Set of drawings with Final Extra Batten

Full Set of drawings with Final Extra Batten

2021

Full Set of Roof Drawings

Full Set of Roof Drawings

2021

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

Product Enquiries

News from VENT

VENT Ridge Vents Now Even Easier to Specify and Install
Why Specify the VB20 Ventilated Batten?
A Tested Solution for Ventilating Roofs and Preventing Heat Loss
Get a free weekly digest of essential news

New and updated architectural products, design solutions, inspiration, technical advice and more when you sign up for EBOSS.