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What to do with Vented Crawl Space that has exposed, uninsulated baseboard pipes

searching4warmth | Posted in Energy Efficiency and Durability on

Looking for advice on a strategy to insulate a vented crawl space that has exposed baseboard heater pipes running through the space. I am located in climate zone 6A (Southern Maine). I recently bought a home that has a full basement under the original part of the home (that houses the heating oil storage tank and Buderus boiler) at some point, there was an addition put on that now sits over a vented CMU foundation crawl space with standard floor joists. The access to this crawl space is in a closet within the addition. There is “conditioned” living space above the crawl space and the floor / space above is significantly colder in the winter than the spaces above the full basement.

Upon going into the crawl space this is what I have observed:

–          Open gravel flooring

–          Exposed, uninsulated baseboard piping passing through the vented crawl space to service the baseboard heaters in the addition spaces

–          Only insulation currently is fiberglass batts stuffed into the rim joist pockets

–          No other insulation on the CMU walls / between floor joists / between shared basement foundation wall and crawl space wall

–          Vent is and has been open (one vent on either side of the home – front and back)

My question is what the heck do I do with this space? And what would be the best way to go about insulating this space? Currently cold winter air is coming in and the floor sheathing is completely exposed to this. My initial 2 lines of thought are to insulate the pipes and spray foam between the floor joists and leave the rest of the crawl space open and vented and treat that as outdoor space. I am not sure if that would keep the pipes warm enough to not run the risk of them freezing because as I understand (after reading some other posts) essentially because the floor joists aren’t insulated some of the heat from above is radiating down and essentially keeping the crawl space warmer which is why miraculously the pipes haven’t frozen yet. My other thought (which seems a lot more costly) would be to entirely seal / encapsulate the crawl space and then to spray foam the rim joists and CMU walls and consider the crawl space to be semi-conditioned and add floor registers into the space above to allow for moisture and humidity control. Are either of these options viable or am I approaching this wrong? Really would like some input from people who know more about moisture control, insulation etc. and how you would approach the situation if it were your house.

– I have attached some pictures showing the situation. And some other conditions I noticed. 


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  1. Expert Member
    Michael Maines | | #1

    This is a good overview of how to build a conditioned crawlspace: If you don't have a contractor, I recommend TC Hafford--they are not far from you and specialize in basements and crawlspaces. (I have no relationship with them but they do good work.)

  2. searching4warmth | | #2

    Thanks for the response I will definitely check them out

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