Ridgid foam under metal roof

Hi I’m new to the form, thank you for taking the time to read my question. I’m about to start building a small cabin 16 x 20 with a shed roof. I’m building it out of Hemlock that we cut down from the property. I want the hemlock rafters (2x10)and hemlock roof sheathing (1x8) to be visible when viewed from below. My concern is getting some R-value on the roof. What is the best way to get some r factor in this scenario? Can rigid foam be applied on top of the Hemlock roof sheathing and then metal roofing put on top of the foam? Thanks Joe		Joseph Peterson 1/24/2018	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/22804/find/
Yes. How tight are the gaps going to be on the 1x8? Rigid foam with a customer rake edge and drip edge is your best approach here.		Eric Novotny An informed customer is the Best Customer! 1/24/2018	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/22805/find/
Eric, Thanks for the reply. The 1x8s will be butted tight so you can’t see the foam when looking up. Would this design need additional battens ontop of the foam to prevent fasteners from deforming the metal if overtighented?		Joseph Peterson 1/25/2018	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/22806/find/
Okay. In that case, I would seal the topside of the decking some some peal and stick Ice/water for an air barrier prior to the installation of the foam. This would make sure that there was no mixing of the outside air with inside air and would help with the condensation concerns. After that, proper thickness of foam attached to the structure prior to the roof and/or sleepers.		Eric Novotny An informed customer is the Best Customer! 1/25/2018	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/22807/find/

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