Replies

1. 
   eddo234 | Mar 04, 2022 01:17pm | #1

   I'm in the same situation with an 1840 house. The circa 1850s addition is on a non-mortared stone foundation (our land is sitting on a ridge of locally well-known sedimentary stone, Panton Stone), with a dirt floor crawlspace. We also have seasonal moisture that runs through the crawlspace. There's no way to divert the seasonal ground water because the ledge is on the surface right up against the house on the uphill side. The ledge goes into the crawl space, and on one side of the space the clearance is about the same as yours. I haven't figured out a way to insulate the half I can't crawl into, so it keeps getting moved lower on my extensive list of things to do. I've thought that simply insulating the walls (in my case I'd have to spray foam because they're stone) won't help a lot because the crawlspace floor will still be very cold, additionally because of the ledge. I've also thought about spray foaming the underside of the subfloor, a very expensive option, and no company will try in such a tight space. If I try to install rigid foam underneath the subfloor I still have the problem of how to fit myself and the foam into the space. I know none of this helps you, just commiserating, I guess. I've asked on a few forums in the past and some of the suggestions, even from "experts" like Martin Holladay and others, were somewhat silly: lift the whole addition and insulate, then lower it (yes, an "expert" actually suggested that), remove the entire addition's finished floor and subfloor, insulate from above and replace all of it (riiiiggghhtt). You said it's never had any venting, how would you access it then?

2. 
   coolwillie | Mar 05, 2022 09:17am | #2

   The most important task to to cover the dirt floor with 6 mil poly, sealed the best you can to the walls. You would need access to at least one side of crawlspace One way to do this in such a crawl space would be to attach a wood furring strip to one end and then push or better pull furring/plastic to other end. Also if there are any outside vents to the crawlspace seal them up.