# venting a flat roof with parapets



## timconnery (Mar 17, 2008)

I'm insulating a flat roof from the inside. I've dropped the ceiling and will have about 4" of airspace between the roof sheeting and insulation. Each joist cavity will join a wall stud cavity which extends up past the top of the joists to provide framing for the parapet. Should I cut a horizontal slot in the parapet across each of the stud cavities on both ends of the roof, add some screening and then flash an awning over the top? The other choice seems to be to put a row of roof vents on both sides but that's 17 vents on each side!


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## tonyBagadonuts (Mar 17, 2008)

Looks like you pretty much listed your options here.


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## the roofing god (Aug 2, 2007)

if the parapet has shingles on the exterior,you`ll have room to put a large gable louvgre inside the parapet wall,dependent on height above roofline(flat),or you can try to drill holes thru the parapet top,put cobra vent,and the cap with metal parapet flashing---without some soffit vents,you won`t get much airflow--you also should look at the quality(r)of your insulation,if it`s low or a cathedral style ceiling,you may be better off not venting the flat roof at all--would be fine with 2"isocyanurate on deck,then install the roofing,and this will keep the condensation from the bottom of the roofing


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