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Insulating inaccessible Rim Joist of 100 yr old house

Aggie2012 | Posted in General Questions on


I am trying to find some advise about insulating the rim Joist area of my 110 year old home. Martin went into detail on this with spray foam and/or XPS rigid foam board which will work fine on the East and West side of my pier and beam house, but the North and south side have a floor joist in the way making the area almost inaccessible. 

When the north wind blows the bedrooms on that side of the house are very cold and I can feel the air running through the light switch outlets inside. (I do have fiberglass batt insulation in the walls but the guy that did the work left a small gap between the studs for the walls to air out and breath but i am not sure that was the right thing to do. 

As you can see from the photos there is not much room. I also would have opted for spray foam instead of the fiberglass batts that you see under my flooring but I don’t have a subfloor and would hate to mess up the beautiful 3/4″ tongue and groove pine that we walk on. 

Should I be concerned for the walls not being able to “breath” being that we sit at 100% humidity alot of the summer. (I am located around 60 miles west of Houston, TX). 
Also does anyone have an idea on how I should fill this cavity?  Spray foam or several cans of Great Stuff shot in this gap hurt anything assuming that’s where the air is entering? Or should this stay open to atmosphere? 

Thank you for any comments/advise


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