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Mistakes were made- insulation

deloshuff | Posted in Energy Efficiency and Durability on

Bryce here.  I have loved reading all the advice.  I didn’t dive in to the study of the “perfect wall” until after i had started my 1,200 sf home addition so a lot of the exterior and foundation design does not work best for exterior insulation and the rest of the home is old school brick/structure/r11 bats/Sheetrock.   We should have designed the walls a lot differently from the start.  

Doing owner/builder and subbing out as little as possible.  Three front sides of the home are brick.  The addition on the back will be siding.  Planning LP Smartside.  New walls are 2×6 then OSB.  I taped all the exterior OSB seams with 3M 8067.  Just wrapped the outside with 10ft Tyvek Commercial to minimize seams.  Installed windows.  

Now what?? 

What do you recommend for the right insulation combo?  Insulation guy proposed closed cell spray foam/Blow in/vapor barrier/Sheetrock.  
Won’t the Blow-in be stuck between the foam on the OSB and the vapor barrier? Seems like a trap for moist air through leaky envelopes? Rain screen on top of the exterior wrap necessary?   Nearly no one in my northern Utah area is doing one!  They just use the cheapest home wrap, no OSB seam tape and no exterior insulation.  Put the LP or Hardi right on the wrap, and insulate inside the walls. 

Im not sure i can make exterior rigid Foam work with the window/door flashing.  Vinyl windows had center install tabs so they don’t stick out very far.  


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  1. Jon_R | | #1

    Use a wall that complies with the recommendations in Table 2 A or B here.

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