Insulated Metal Panel or SIP

Charles Gordon
3/31/2014
I am building a house that the plans call for two wings of the house to have 9 to 12 hipped roofs with the ceilings to be cathedral ceilings with exposed rafters and exposed 1x6 planks between the rafters. What is your advice as to whether to use Insulated Metal Panel Roofing with standing seams or Structurally Insulated Panels (SIP) so that we can have sufficient insulation in the roofing material. Otherwise the plan is to insulate between the rafters with spray in foam and then build in fake 1x6 planks between fake rafters. It seems quicker and hopefully cheaper to use Insulated Panel Roofing or SIPs. What is your advice? Also, how would I make the house air tight in this area if I don't use sprayed in foam in this area of the house? Would the underlayment (Fire & Ice??) on top of the decking under the Insulated Metal Panels be sufficient? Thanks
Todd Miller
Classic Products, Inc.
4/1/2014
Wow. Sounds like a good project you have going. I have not seen a lot of insulated metal panels used residentially but those are great products with good insulating values and they certainly could be used that way.I would think though that by using SIP panels, you would have greater flexibility down the road if you wanted to change the roofing material. You also possibly could get greater R Value from them due to thicker panels being available. As far as a vapor barrier ... you could use polyethylene someplace in the assembly as a vapor / air barrier.
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4/1/2014
SIPs seem a whole bunch easier here as well. They have them in the residential code requiring insulation thicknesses and should be easily incorporated to this type of construction. Vapor retarder recommendations depends on where the home is but getting all the air leaks sealed up is paramount to performance.
Charles Gordon
4/2/2014
The following are probably dumb questions but I am not a builder. Which companies sell SIP's for residential roofs that will pass hurricane wind codes? What exactly is a SIP as compared to a Insulated metal panel? How is Polyethylene applied?
Todd Miller
Classic Products, Inc.
4/2/2014
SIP's are insulation (either urethane or EPS) laminated typically between two sheets of OSB. Some of them have ventilation channels in them. You'd need to contact individual SIP manufacturers for code and wind loading info. There is a SIPA organization of SIP manufacturers that may be of value to you. Many SIPs are designed, with proper installation to be vapor barriers. Again, you'd need to work with a SIP manufacturer.
Guest User
12/22/2014
I am of the opinion that OSB on SIPs can absorb moisture be it from inside the house as condensation, or externally, and eventually start to deteriorate. Insulated metal panels up to R 42 or greater for large commercial buildings are available with metal bonded on both sides. I am investigating the metal ones for roof and walls and if cost does not kill it re: averaged out on ROI over 20 years, it is already my preference. If I can seal a stiff SIPs at joists, rafters, etc, surely I can do it for a metal panel that is flat on the underside. Open to lots of input!

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