TECHNICAL INFORMATION: Roof Ventilation
Onduline is resistant to the build up of condensation. However any single thickness roofing material is at risk of condensation formation during the
winter months. On most roof areas the ventilation provided by leaving the corrugations open at eaves and ridges is sufficient to avoid the problem.
However on roof areas over buildings affected by high humidity such as swimming pools or those containing livestock, condensation could be
a problem unless additional cross-flow ventilation is provided by means of Onduline roof or ridge ventilators.
It is recommended that on high risk structures Ondutiss vapour check and insulation is incorporated at ceiling level or as part of a panelled roof
section in order to reduce humidity levels in the roof space.
For roof pitches less than 15 degrees low level at eaves should be not less than 25,000m² per linear metre. Onduline requires additional ventilation at
soffit. For roof pitches greater than 15 degrees low level ventilation at eaves should not be less than 10,000mm² per linear metre. High level
ventilation in each case should not be less than 5000mm² per linear metre.
Note: The use of an Onduline ventilator mid span is recommended on roof spans greater than 12 metres from eaves to ridge. |
