Building Construction Handbook, Eighth Edition

Roof ventilation † provision of eaves ventilation alone should

allow adequate air circulation in most situations. However, in some

climatic conditions and where the air movement is not directly at

right angles to the building, moist air can be trapped in the roof

apex. Therefore, supplementary ridge ventilation is recommended.

Note: ventilation dimensions shown relate to a continuous

strip (or equivalent) of at least the given gap.

Ventilation of Roof Spaces---2