Venting A Flat Roof With Parapets

Provide venting to each wall cavity.

Venting a flat roof with parapets.

Good attic ventilation is important for preventing ice dams in the winter. When thermal insulation is placed below the deck the ventilation must also be on the underside. There are two types of flat roof systems warm and cold roofs which affect the positioning of the ventilation. Flat roof ventilation allows for the circulation of air in the property particularly for warmer rooms in residential buildings.

We also have a parapet on a flat roof and the ventilation solution is not through the cladding but the design flows air over the parapet. The solution seems reasonable but we are definitely going to end up with a cold roof though not in the traditional sense. Can use round louvered soffit vents to limit bulk water intrusion if venting holes are in exposed location. That way you can use the parapet wall to detail a vent in the back side of it.

Venting in wood framed parapets. Alternatively you can drill lots of holes to connect the joist spaces or use web trusses and then install vents in the flat roof surface as in commercial. Attic must have 5 sq. Ft of vent space half dedicated for air intake in the soffits and the other half for exhaust on the roof.

For areas which do not need above cover. Nothing built yet but in theory the solution should work well. Instead the air is vented through the roof to the parapet walls the parapet then incorporates a continuous strip vent beneath the cap flashing.