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A school lesson (roof ventilation) - Build 180(2020)

Abbreviation
A school lesson
Valid from
01/10/2020

Information provider
BRANZ Limited
Information type
BUILD article
Format
Website, PDF

Description

BRANZ was called into a Dunedin school where too much ventilation caused excessive condensation in a large roof space. Understanding why this happened points to warm roofs being better in some locations.

Ventilating roofs is generally considered to be a good approach to managing moisture in the roof space and to make the overall roof assembly more robust, reducing the risk of condensation.

A valid question is, can there be too much roof ventilation? We recently saw a school where too much ventilation caused excessive condensation in a large roof space. To find out why this happened, we looked at climatic conditions, location, orientation and building design.

Scope

This article includes:

  • Building design, orientation, solar gains
  • Roof fitted with wind-driven ventilators
  • High risk of condensation in this case
    • Air condenses on cladding and underlay
    • Extractor fan brings in more moist air
    • Air barrier may help but not enough
    • Even passive vents could be risky here
  • Warm roof a better solution here
  • Ventilating cold roofs usually helpful
For assistance with locating previous versions, please contact the information provider.
View on Information Provider website Download this resource (PDF, 12.5MB)
For assistance with locating previous versions, please contact the information provider.
This resource is not cited by any other resources.

A school lesson (roof ventilation) - Build 180(2020)

This document is not CITED BY any other resources:

A school lesson (roof ventilation) - Build 180(2020)

Description

BRANZ was called into a Dunedin school where too much ventilation caused excessive condensation in a large roof space. Understanding why this happened points to warm roofs being better in some locations.

Ventilating roofs is generally considered to be a good approach to managing moisture in the roof space and to make the overall roof assembly more robust, reducing the risk of condensation.

A valid question is, can there be too much roof ventilation? We recently saw a school where too much ventilation caused excessive condensation in a large roof space. To find out why this happened, we looked at climatic conditions, location, orientation and building design.

View on Information Provider website Download this resource (PDF, 12.5MB)
A school lesson (roof ventilation) - Build 180(2020)
Description

BRANZ was called into a Dunedin school where too much ventilation caused excessive condensation in a large roof space. Understanding why this happened points to warm roofs being better in some locations.

Ventilating roofs is generally considered to be a good approach to managing moisture in the roof space and to make the overall roof assembly more robust, reducing the risk of condensation.

A valid question is, can there be too much roof ventilation? We recently saw a school where too much ventilation caused excessive condensation in a large roof space. To find out why this happened, we looked at climatic conditions, location, orientation and building design.

View on Information Provider website Download this resource (PDF, 12.5MB)
This resource does not cite any other resources.

A school lesson (roof ventilation) - Build 180(2020)

This resource does not CITE any other resources.
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