2021 IRC Insulation requirements

[alaskajoe]

How is everyone dealing with the requirements for insulation when it comes to the R value of 20 + 5ci in the stud cavity. Adding that 5ci is putting a big cost on construction. If you use rock wool at 5.5" it is just R-23

 

[rktect 1]

Climate zone 5 - Its required either R-20 + 5ci or R-13 + 10ci.

How else am I supposed to deal with that? They can certainly provide compliance through section 406.

 

[tbz]

How is everyone dealing with the requirements for insulation when it comes to the R value of 20 + 5ci in the stud cavity. Adding that 5ci is putting a big cost on construction. If you use rock wool at 5.5" it is just R-23

So, will the R-value Zip sheathing get you there? I personally prefer the R-9, but they make an R-6 also.

I like it a lot, not sure how simple that is to get in your neck of the woods but works great IMO, cost is not really that bad in my neck of the woods.

https://www.huberwood.com/zip-system/insulated-r-sheathing#products

 

[Yankee Chronicler]

How is everyone dealing with the requirements for insulation when it comes to the R value of 20 + 5ci in the stud cavity. Adding that 5ci is putting a big cost on construction. If you use rock wool at 5.5" it is just R-23

It's a code requirement. People around here deal with it by doing it.

 

[Paul Sweet]

You have to add 1" foam exterior insulation and use much longer nails for your siding. If you use wood siding it has to have an air space behind it or it will warp badly. I found that out the hard way on a house I built in the late 70s.

 

[bill1952]

I wonder if the ZIP R9 - which is an actual R9.6 - is accepted for the CI in zone 6.

Does wood warp on ZIP - since it's basically OSB and house wrap?

 

[ICE]

It's a code requirement. People around here deal with it by doing it.

Ya know, I wonder why Joe didn’t think of that?