2015 MN energy code questions

[eric4105]

I am planning on putting insulation and finishing the walls in my garage. The city says I need a permit and need to follow the 2015 Minnesota Energy Code. The walls are just that buffalo/fiberboard with uninsulated siding.

Based on this it looks like I need r20 or better for the walls. Is that the correct interpretation (the R13+5 wouldn't apply)? If I am going to do rolls, it looks like R25 is the most common value?

Also, are there any other provisions in the code that I need to be aware of?

Thanks!

 

[Mr.N]

So your garage is attached, correct?
My understand in this applies to "residential buildings" so as you are talking a garage... how would it be legal to sell the house if the garage was covered under this code?

 

[eric4105]

It's attached. Yeah I feel like at a minimum it should be grandfathered in. The walls are 2x4 and I think the >20 requirement is really meant for newer construction with 2x6s and R19 insulation.

I'm still kind of debating all of this with the city. Not sure that I could have compressed the R25 enough. I'm now thinking a better approach would be to try use R13 with a R5 foam board over the top (and maybe tape those and use them as the vapor barrier).