Author Topic: Crawlspace Encapsulation  (Read 2803 times)

PantsOnFire

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Crawlspace Encapsulation
« on: January 15, 2014, 01:23:48 PM »
I'm considering encapsulating our unconditioned basement crawlspace.  The house is 60 years old, with a rough concrete floor (sloped, and pretty lumpy in many spots) and field stone & mortar perimeter foundation.  There is some very minor water intrusion through two of the foundation walls which I intend to remedy first (we have masons coming out after the ground thaws to do brick repair and they will address the trouble areas from the outside.) 

I'm familiar with the basics of using thick plastic film to make a "tub" across the floor and partway up the walls.  All of the instructional videos I've seen on this involve pretty flat floors and block or poured concrete foundation walls so it appears very simple.  I'm sure our uneven walls and floor will make things more difficult. 

I'm considering using a liquid sealer on the walls first.  Any other suggestions? 

Any ideas what the materials would cost and how long something like this might take?  I can price out the film and tape but I'm not sure what other "hidden" costs might be involved.  I haven't gotten exact measurements but I estimate the space to be about 32' x 20'.  The height slopes from front to back but averages about 4'. 

Greg

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Re: Crawlspace Encapsulation
« Reply #1 on: January 15, 2014, 01:28:23 PM »
An easier and more affordable option for an unconditioned space is polyethylene sheeting (usually 6mil) laid on the flat parts.  This creates a vapor barrier to prevent ground moisture wicking up through the floor (slab in your case, around my area usually dirt) and creating humidity under the house.  Overlap the poly a foot or two where there are seams and you don't even really need to tape it.

TomTX

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Re: Crawlspace Encapsulation
« Reply #2 on: January 15, 2014, 07:26:04 PM »
Waterproof whatever you can from the outside as well.

PantsOnFire

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Re: Crawlspace Encapsulation
« Reply #3 on: January 29, 2014, 09:23:02 AM »
Agree with both of you.  I'm going to make sure the masons stop any actual leaks from the outside, and I'm not going to go nuts trying to make the poly airtight.  I did a first pass rounding up debris off the floor down there and I'll do an actual broom-sweep before I lay down poly. 

Any thoughts on sprayfoam insulation vs. blanket insulation on the foundation walls?  Sprayfoam seems superior, but if there's significant surface prep involved with that, the low-tech blanket insulation might win out. 

Milspecstache

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Re: Crawlspace Encapsulation
« Reply #4 on: January 29, 2014, 09:51:53 AM »
There are kits where you can sprayfoam yourself.  Not cheap, however.  Cheapest solution will be batten insulation which would be help up with the wire insulation hangers they sell.

Where sprayfoam is awesome is where you have moisture passing through.  With the poly put down there shouldn't be as much of a moisture problem.

 

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