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Community and Q&A

Dirt crawl space confusion and mixed advice

Sue Russell | Posted in Energy Efficiency and Durability on

We live in a 150-year old schoolhouse – brick over plank walls – Walls and attic insulated well. STone and mortar foundation ~ four ‘ deep two’ thick with large beams on top supporting building.
Dirt crawl space that’s 2′ – 5′ deep (depending on how much it was dug it out for water heater, furnace, etc. ) Very dry all year… furnace ductwork and plumbing fine…. one heat duct to keep space warmish. No insulation. A vent at either end through foundation – open in summer; sealed in winter. We are in central Ontario so quite cold in winter but building seems easy to heat and floors not cold. So we have just “left it alone” – some plastic down on crawlspace floor to keep worst of dirt off when doing plumbing etc maintenance. Not a place I spend a lot of time in!
So if no big problems, seems to me sealing the CS, trying to figure out to insulate above and walls etc will just be a headache and cause problems. Thoughts?


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  1. David Meiland | | #1

    Part of the reason the crawl space is warm and dry is that you are heating it, both directly with one register and also with leakage from whatever ductwork is down there. If it were me, I would air-seal and insulate the floor, seal and insulate all the ductwork, close the register that's in the crawl space, and put a poly ground sheet over the entire area. I would experiment with keeping the vents closed in the winter. I would look for a place inside the building to put the water heater. Depending on the building layout I would try to move away from ducted air for heating.

    You say the building seems easy to heat, but the real question is, how many BTUs are you using?

  2. GBA Editor
    Martin Holladay | | #2

    Many people have a situation like yours: they live in an old house that isn't as well insulated or air-sealed as a new house, but they can afford the energy bills and they are happy.

    If you're happy, there aren't any compelling reasons to make any changes to your house -- except to lower your carbon footprint and reduce your contribution to global climate change.

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