Concrete floor question in crawlspace?
I’m begining work on insulating my unvented crawlspace, it is under an addition to a house with a full basement. Two sides are to the outside elements, one side is to the full basement, and the other is to a enclosed breezeway. When the addition was done (before me) the floor was rough poured concrete, looks like it’s over plastic, but it was not poured complete (all the way to the four walls), it was left short about 6-8 inches (dirt showing) from the two walls exposed to the elements. Do you think this was done for expansion reasons, or they ran out of concrete? I want to insulate this space, and started to attach the foam board to the block, but I,m unsure how to proceed with the area where there is no concrete finished up to the wall. Would I need to install an expansion joint and finish pouring the concrete up against the wall, or can I use the foam board run down the wall to the ground as the expansion joint, do I need an expansion joint? The finish concrete inside would be at ground level outside. I’m in northern Ohio if that makes a difference
Thanks for the help!
Replies
Just stop the foam board a few inches above the dirt in the unfinished area so you can eyeball it from time to time to see it there are any termite tubes starting. (Probably a good idea where the rat floor is against the foundation as well.)
Blow some conditioned air into the crawl, but leave the foundation vents open a tiny bit so the conditioned air goes outside and doesn't get recirculated through the house.
Be sure your exterior water controls are in good condition (positive grading away from the house and 10' downspout extensions well past the over-dig area: you don't want water saturating the foundation wall and wicking up into the sill plate.
Doesn't happen often, but I've seen it rot out sillplates in the Toledo area.
(Depends on how much exposed foundation is above grade - often not much in our area.)
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