Howdy folks,
First off, thanks for this great resource. am building a 34’x38′ ‘addition’ onto my garage with an ADU in it to pay for it all up here in Lebanon, NH (climate zone 6).
Got a screaming deal on some used commercial 3″ polyiso and so decided to base my insulation plans around that.
Roof is 12′ rafters to be filled with mineral wool, then 5/8″ Huber zip system, then the polyiso on top. Intello membrane on the interior of the conditioned space.
The roofing contractor (standing seam, due to low roof slope and desire to DIY install solar in the spring) needs to have sheathing under the metal.
Seems crazy to me to do ANOTHER layer of zip system (god just the tape is so expensive) on top of the foam, but if I’m going to go to all the trouble of paying down 1/2 OSB, I might as well get some 7/16″ Huber and have a belt and suspenders against moisture… right? It is a very low slope… one side is about 1.1/12 (I know, I’m crazy) and there’s a valley in it where it meets the existing building (I know, I know) so to some extent I feel like all protection against moisture there is good.
Then I’m like, well, if I’m going to put zip on top, I might as well get zip R6 and use the EPS exterior to keep my polyiso a little warmer so that it doesn’t do the cold-weather performance drop that polyiso is so famous for… it’s only a little bit more money…
You see my conundrum.
Bonus question – I have some 6″ screws to fasten it down, but how in gods name do I keep track of where the rafters are through insulation and another layer of sheathing? I will admit that my layout is not as regular as one might like.
Thaaaanks.
~Rory
Replies
Your question seems to be asking about the comparison between two materials: "Huber over foam over Huber." However, without additional context or information, it's challenging to provide a specific answer. "Huber" could refer to various things, including a company name, a specific product, or a material, and "foam" could represent various types of foam materials. To offer a meaningful comparison, it's crucial to clarify what you mean by "Huber," specify the type of foam, and provide more details about the context or application you are referring to so that a relevant comparison can be made.