FHA Minimum PropertyStandards require 1 square foot of net free attic vent area for every 150 feet of attic floorarea; or one square foot per every 300 square feet, if vapor barrier is installed on the warmside of the ceiling, or at least one half the ventilation area is provided near the ridge.

Adequate ventilation under the roof deck must be provided to prevent harmful condensation in winter and heat build-up in summer. These conditions can cause: A.) accelerated roof weathering; B.) Deck rot and attic fungus; C.) Shingle distortion/cracking due to deck movement; D.) Blisters.

Atlas will not be responsible for damage to shingles as a result of inadequate ventilation. Ventilation provisions must meet or exceed current FHA Minimum Property Standards and conform to all building codes and regulations.

To best ensure adequate ventilation and circulation of air, a combination of vents at ridge and eaves should be used. All roof structures, especially mansard and cathedral type ceilings, must have complete thorough ventilation from bottom to top.