Shallow Vented Crawlspace Insulation/Encapsulation – GreenBuildingAdvisor

Hello all, I’m Daniel. Here is my dilemma, I am trying to figure out a way to insulate and/or encapsulate a very shallow vented crawlspace under an older home. I’m located in central Kentucky, climate zone 4. The house was built in the 1950’s and is cobbled together with a series of cedar posts and CMU as the foundation piers, with CMU stem walls around the perimeter. The crawlspace stays dry, and the humidity only really raises with our humid summers. The issue I have is access, as the floor framing is only 6-10 in. above the dirt floor and with so many piers, reaching the front of the house is practically impossible. So, even if I could adequately air seal and insulate the stem walls with maybe an R-10 foam board on the exterior, I would not be able to properly install a vapor barrier on the dirt floor, which I’m afraid would defeat the purpose of encapsulating from the outside. Short of taking out all of the flooring and subfloor, piecing together a vapor barrier that way, and possibly spray foaming the inside of the stem walls, has anyone found a way to insulate and air seal from the outside and still be able to control moisture levels over a dirt floor? Our winters don’t get terribly cold, but the energy loss and discomfort of the floors is quite substantial.

My other thought was to air seal the outside of the crawl walls as best I could, remove just the flooring and install an electric mesh style of floor heating. But again, I’m afraid without proper air sealing and insulation of the crawlspace walls I would be introducing potential condensation issues in the crawlspace.  

Any advice or experience with a shallow crawl like this would be appreciated!