Don’t say it. Amazing. Photograph 8: Cellular PVC Trim—Trim fascia and soffit installed. The 6 inches of rigid insulation added to the top of the existing roof deck needed to be done in a manner that was “invisible”. We had a simple roof. We don’t have any local codes that cover the topic, so I’ve been trying to look elsewhere for best practices before we do this. Rigid foam insulation creates a solid barrier between the inside and outside of your house, acting as an obstacle in the way of heat and cold transfer. The use of above-deck thermal insulation shall be permitted provided such insulation is covered with an approved roof covering and complies with FM 4450 or UL 1256. I was planning on the top one being a water shield, but still be vapor and air permeable, so if water did get under it, it should still be able to dry. Read on. This foam is applied over the top of the membrane that came down from the roof deck catching the wall control layers. What was the original roof construction? Though the material itself is low in insulation R-value, metal roofing can be applied over rigid-foam insulation that has very high R-values. Rigid Foam Insulation Installation Prepare Roof Deck The bottom layer of a single-ply membrane roofing system is the roof deck or substrate. But double walls are tricky to construct, increase the risk of moisture damage and in my view they don’t make a lot of sense. Did you know that a metal roof doesn’t have to look like metal? Wrote about the ice damming thing already as well (BSI-046: Dam Ice Dam). In 1995 that seemed pretty good. This one looks to be the easiest read on the subject, but they’re still not very in-depth on the topic:https://www.roofingcontractor.com/articles/86708-web-exclusive-important-roofing-codes, New comments cannot be posted and votes cannot be cast, More posts from the Construction community. Apply 2x4s on the flat over each rafter and fasten with 6 inch screws. I am real good at fixing stuff—especially stuff that I break. Insulating a metal shed roof can keep a shed warmer even without a heat source. Notice the increase in overhang dimension on the gable ends. Located in rural Mississippi, so it is hot and humid climate. Another option for noise reduction is foam roofing. Plywood sheathing, then roofing felt, than 1.5” rigid foam, Metal roofing. But at the end the comfort and quiet thing won the day for me. This will be in rural Mississippi, which is hot and wet a good portion of the year. He said if he did it again, he’d use a different product for the air gap, I think. This is not just to match the overhang on the front. If there are plenty of small holes (pinhole size), a roofing contractor can spray foam right over top of them. This was then “foamed” to complete the air seal. This stuff needs to be “invisible” or it will not happen. I was going to make sure it would end up energy efficient. Roofing membranes can be made out of a variety of materials: Synthetic Rubber; Thermoplastic Membrane; Modified Bitumen . Photograph 13: Finished Trim Details—Hah! New shingles were installed over a fully adhered membrane applied directly to the original roof decking. One day folks will actually think that energy might be important. Because I phased the work, I had to use spray polyurethane foam—the 2 lb/ft3 density stuff—in the cavities during the original renovation. What to do? Got two bedrooms and a bathroom, a place to store old ASHRAE Journals and a place for mechanicals. Yes, I will share the experience. If I recall correctly, he got a call back because the radiant heat from the metal absolutely cooked his peel and stick water barrier. You may want to read whichever one of these is applicable to where you are building: https://www.amazon.com/default/e/B001JS3N9C/ref=sr_ntt_srch_lnk_2?qid=1532226052&sr=8-2&redirectedFromKindleDbs=true. Ideally suited for Fabral standing seam roofs, ACFoam®-III Polyiso Roof Insulation can be used without a thermal barrier. This foam can be used on either the outside or the inside of the sheathing. And we are good at blaming the architect for the lousy building enclosure that we are stuck dealing with. Thanks for the suggestions. The attic had windows at the gable ends but the attic was unfinished. Tape seams in rigid foam. It happens, even to self proclaimed gurus. Did the attached barn—not particularly well—and ended up redoing it. In went some skylights on the back-side (Photograph 1) and the rafters got sprayed full of 2 lb/ft3 density spray polyurethane foam (SPF) (Photograph 2). I found that statement online in several places, and I believe I should be ok with the way that is interpreted. Ouch. Well one thing led to another and another and a couple of years turned into a decade. My plan is to put roof decking, water/air/vapor peel-and-stick membrane, 2 x 2.5” foam boards, waterproofing layer (air/vapor permeable), 1x4 battens (ideally screwed all the way through to rafters), then standing seam metal roofing. I would like to read up on that. Not bad eh? I am planning to have the roof decking fastened to rafters, fully-adhered air/water/vapor membrane, insulation, waterproofing layer (vapor permeable so any water that gets underneath can dry), battens on top fastened all the way through to rafters, then metal roofing panels. I’ve seen people go with OSB over the foam layer, but they are usually putting shingles over that. According to the manufacturer’s instructions, install the … Note the 2 lb/ft3 spray polyurethane foam enhancing the air seal around the extended rafters. 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