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Opinions on this Unvented Roof Assembly Plan

Lynchpinhandymanserv | Posted in Green Building Techniques on

I am building a home in 6B and I’m almost finished setting trusses and about to install the roof sheathing.  It is more of a passive solar house with lots of windows and a few different roof pitches.  I have a slab on frost wall with in floor heat and a few mini split units but no forced air or ducts for conditioning.  I would like to have an unvented roof but from what I’ve read it has to be installed perfectly.  This is what I’m thinking for installation order from top to bottom on the roof: 24 gauge metal roofing, furring strips, 30 lb felt paper, 5/8″ Osb with seams sealed, then sprayed foam on underside of roof decking from attic(not sure how thick it should be sprayed).  I haven’t house wrapped the walls yet but they are 2×6 and I hope to have metal standing seam siding, lathe for rainscreen, house wrap, 7/16″ osb, and cavity fiberglass insulation.

Any words of wisdom on these materials and the order?  This site is amazing and I appreciate any help!

Thank You

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  1. Lynchpinhandymanserv | | #1

    Update: I heard back from the metal roof supplier and they told me that product needs to be directly fastened to the roof decking, so maybe I can't have an unvented roof?

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