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Crawl space renovation – floor choice?

paddington_22 | Posted in Green Building Techniques on

I am currently insulating my crawlspace, and then will redo the floor — currently it is just earth.

(I guess we have a CS in the first place, because the house is split levels, with a partial basement, and is built on a slope…). So there is no (apparent) groundwater around…

Still, the even though the CS does not appear to be *very* damp, it IS damp-ish, and I don’t want said damp, nor the unpleasant musty smell that goes with it !

If I understood right, there seem to be two recommended methods for floor treatment – either encapsulation using a vapor barrier, or pouring of a concrete slab.

I only have 33 inches of free height at best, and given the uneven nature of the floor (ups and downs, trench, slopes…), I wanted to make the job as easy as possible for myself…

So I don’t see me mixing loads of concrete down there, and I cannot barrow concrete in, as no access, and I cannot afford to have a concrete pumper on site.

Also, I cannot quite see a polythene vapour barrier looking OK, given the contours. The CS is 40 foot long by 13 foot wide. Access door is 30 inches square.

So I am wondering if I can take a third route, namely, “grossly” leveling the floor (removing rubble, rocks, a certain amount of earth), then mixing in some bags of lime, and adding water, to stabilize the earth and “lock in” the fusty smell.

Would this make the CS any healther ?

Would appreciate your feedback

Green Villager
(N France)

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  1. GBA Editor
    Martin Holladay | | #1

    Green Villager,
    As with any job, there is usually a correct way to proceed. Whenever a homeowner tells me, "I can't afford to do it the right way. Can you recommend a cheap way to do it?" I get nervous.

    The best way to cover a crawl space floor is with a concrete slab that has been poured over a layer of polyethylene. If the floor is uneven, it needs to be graded level, by removing material from the high spots and filling in the low spots with crushed stone.

    If you can't afford a slab, at least perform the leveling work. Then install a layer of polyethylene with sealed seams.

    Before you proceed with any of this work, however, you need to do everything you can to dry out the crawl space. For more information on this topic, see Fixing a Wet Basement. (Although this article was written with basements in mind, most of the advice applies to crawl spaces as well.)

    For more information on crawl spaces, see Building an Unvented Crawl Space.

  2. paddington_22 | | #2

    Excellent, Martin, many thanks for your advice !

    In particular, I read your article about Fixing a wet Basement - it is brilliant - and it is clear that I need a SWALE, first of all...

    Also thanks for explaining about need to dry out the CS first of all -- that would not necessarily have occurred to me !

    I took a closer look, around the CS, and I obviously need some insulation around a cold-water pipe as it is causing drips.

    Many thanks again; I'll do the preparatory stuff first, then follow your advice to the letter !

    P.S. My old man (ex-aero-engine fitter) always told me, "If a job is worth doing, then it's worth doing properly"...

    Hapy New Year !
    Green Villager

  3. GBA Editor
    Martin Holladay | | #3

    Green Villager,
    Bonne chance et bonne année!

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