Rigid insulation over old roof | Ask The Experts Forum

keith summers 6/30/2008	Hi: I have a remote cabin in Ontario. It is heated 6 to 7 times each winter for 2-3 days. Pitch varies from 3:12 to 12:12. Shortest length of panel is 16'. The existing roof is mineral face roll roofing over 30# felt over 2" rough sawn decking on log timbers. I plan to place 2'x8'x2" rigid foam between 2" x2" stringers nailed parallel to the ridge line with metal panels perpendicular on top of that. I plan to face the eaves and gable ends with 2" x 4" strips. This leaves a flat surface bounded by 2" lumber with 24" OC stringers for fastening. My questions: 1. Sound OK? 2. OK to leave the existing roll roofing in place? 3. Could I go to 48" OC stringers and increased space between fasteners? Thanks for any help you can offer	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/11674/find/
Todd Miller Isaiah Industries, Inc. 7/13/2008	Your original plan sounds good. Is there any ventilation there at all now?	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/11675/find/
Guest User 7/15/2008	There is no insulation at all on the roof at this time. The plan is to have this sequence from the interior out: 2" rough sawn planking, existing 30# felt, existing mineral face roll roofing, 2" pink foam, metal roof panels.	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/11676/find/
Guest User 7/15/2008	Keith, I would install an underlayment over the rigid insulation. We use stress plates to fasten the insulation and underlayment.	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/11677/find/
Guest User 7/17/2008	Do you want the 3:12 sections to be "walkable?" Does it make any sense at all to run the 2x2s perpendicular to the ridge to facilitate ventilation? I just insulated a 2:12 roof with 3 1/2" rigid foam w/2x4s on edge @ 16o.c.. However, if you are only heating it a handful of times... your plan with 2" foam should yield R13?	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/11678/find/

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