Ventilating cold deck flat roofs.

The current recommended minimal ventilation level for the cold deck flat roof design is evaluated using an experimental roof. The work suggests that there may be a need for ventilation to be increased above the minimal level in instances where natural draught ventilation is low or where roofs are of complex plan. Results of this work are under consideration by the British Standards Institution as part of an overall review of flat roof design recommendations. In the interim this Information Paper offers provisional guidance for designers and those involved in the maintenance and upkeep of cold deck roofs.