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dgeist

Roof Renovation Questions/Recommendations?

dgeist
9 years ago

I have a 1970s era two-story (big rectangle) home with the original asphalt shingles in place. It is a hip roof and has adequate soffit inlets but very poor peak (output) venting. radiant heat is a pretty big issue and is contributing to comfort issues in the upstairs rooms. I've considered encapsulating the entire space with closed cell SPF but it's prohibitively expensive. I would like to re-shingle, add ridge venting, and provide a continuous radiant barrier on the under side the the rafter-bays as less expensive and more traditional alternative. Here's the questions:

1) As it's a hip construction, how does one allow for airflow where hip raters and jack rafters meet (where the cavity ends before the roofline? Holes drilled? Notching?

2) Continuous foil sheeting seems to be the most cost effective radiant barrier, but I'd like a rigid baffle for the ventilation channel, too. 1/2" foil-faced polyiso sheets fastened continuously to the inside rafter edge seem to fit the bill, but is there an easier/faster/cheaper way that would still perform both purposes?

3) when I install the radiant barrier, most recommendations include leaving a gap between it and the insulation on the attic floor. Is this to prevent contact (and transmission of stored heat) between the barrier and the insulation? Wouldn't this allow for free airflow near the soffit, decreasing the effectiveness far more than it would transmit heat to the floor joist materials?

Hopefully, I can bring the ambient temps in the attic down to manageable levels so I can consider using the space for ducting new HVAC gear...hopefully.

Thanks,
Dan

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