THE CODE CONNECTION

How are overframed roofs generally detailed for ventilation and vapor retarding? I am designing a raftered roof system where two rooflines "tee" into each other. Do I have to ventilate the overframed space (attic?) These rafters have no option for incoming ventilation air except for openings cut in the sheathing as they terminate at an interior gable wall. This wall needs to be insulated and have a vapor barrier installed, correct? I suppose these are more construction questions than anything, but I am trying to pull out requirements from the IRC and am having a difficult time doing so.

Thanks in advance

It's a little difficult to imagine this without a diagram but here are some ideas. It's more than a code issue - its necessary from a practical viewpoint. Any unconditioned, concealed attic space will trap moisture that will condense unless its vented. The most common approach is to use soffit and ridge vents. Interconnected roof sections can work together but if circulation is not gravity fed you may consider a powered vent. Its best if each section of roof is vented directly. Think of your "insulation envelope" as the separation between those spaces that require venting and those that do not. Wherever you have insulation, the moisture barrier will be on the warm side. You may want to consult your fave local architect using a diagram - check with you local chapter of the American Institute of Architects. Good Luck! T. Welker AIA