Retrofit exterior insulation can’t be continuous
I’m re siding my 1953 house (south dakota, zone 6a) I’m having them add 2″ of eps and a rainscreen along with the LP smartside. I just realised I’ve been reading about how important it is for the insulation to be continous but mine wont be. The basement is mostly below grade but the tops of the basement walls go above grade for a foot or two. The front and one side of these foundation walls have decorative rock, the other sides are just normal. I wasnt intending on covering the two bare sides of foundation or the decorative rock. in addition I also have concrete steps that dont have enough wiggle room for insulation to fit between them and the house.
my house has no insulation in the walls of the main floor except for in the bathroom a previous owner remodeled. I’m adding in r13 kraft faced fiberglass to all stud bays then covering with osb, 2″ eps, tyvek drain wrap, rainscreen then the siding.
-Will the R value of that wall be lowered because of the exposed foundation below it?
-How much lower R value would it be?
-Should I add more insulation to help cover any r value losses I have?
-Or even if it is less R value is it really going to be just fine as is and I will be patting myself on the back all next winter?
-Off subject question- exterior insulation & rain screens are both very rare in my area so my crew is totally inexperienced. I’m thinking I should add an additional layer of housewrap over the osb sheathing as insurance incase of air barrier failures happen in the taped foamboard or tyvek drain wrap? -What kind would be a safe and hopefully inexpensive choice?
-Any glaring errors in my plan you would point out and/or extra advice/opinions are extremely welcome.
Thank you GBA, you are amazing!
GBA Detail Library
A collection of one thousand construction details organized by climate and house part