Design and performance of roofs.

Surveys factors influencing roof design with respect to energy conservation. Discusses thermal insulation, condensation, ventilation and insolation. Recommendations to prevent condensation in attics include the introduction of a vapour barrier on the warm side of the ceiling structure; provision of ashield in the roof to prevent the ingress of rain that is permeable to water vapour; ventilation of the roof space to the outside air; and either blowing dry air into the roof space or sucking into the house air from the attic and expelling high humidity air intermittently from the house, or both.