A school lesson
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.
This website is best viewed on a newer browser than the one you are using. Learn about upgrading your browser (opens in a new window/tab)
Welcome to BRANZ Build. Skip to main content.
Showing results 1-7 of 7
Do you want to try searching all of BRANZ?
Order by:
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.
Twenty years ago, roofs didn’t need to be specifically ventilated. Today, things are different. That’s because 21st century homes are more airtight, and if they aren’t aired, condensation may form.
BRANZ has been measuring moisture levels in a school’s classrooms. This information is providing a sound basis for understanding the indoor climate and designing moisture-safe long-span roofs in schools.
Ventilation of cold roof designs in New Zealand doesn’t always go smoothly. Here, BRANZ physicists hand over to a couple of professional builders who have long been at the coalface dealing with roof moisture issues on their projects.
BRANZ physicists have developed a useful calculation for designers to work out the minimum number and area of vents required in roof spaces.
Some roof designs, such as skillion roofs, must include ventilation to manage roof moisture. Recent BRANZ research provides advice on the best place for effective vent openings in low wind zones.
As we push for higher performance from our houses, expectations for airtightness and ventilation are changing rapidly. Some changes will be needed in design to improve airtightness, and mechanical ventilation is likely to soon be the norm.