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.
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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.
A recently completed major BRANZ research project has improved understanding of how roofing underlays handle moisture in roofs and led to the development of a new test suitable for a wider range of roofing underlays.
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.
Independent assessors carrying out the 2015/16 BRANZ House Condition Survey rated one-fifth of our housing stock as poorly maintained. Where are the problems areas, and why is maintenance being deferred?
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.
Recently, several cases of an insidious new form of thermal bridging have been seen. Aggravating factors have been identified that contributed to the problem, so there are now lessons to be learnt to avoid this on other buildings.
A recent trip to North America provided opportunities for further refining the BRANZ moisture research programme. Some of the papers presented at a building physics conference are highlighted here.