I’ve seen white stuff, clear stuff, and black stuff used in other people’s crawlspaces. Of the black stuff, I’ve seen plastic looking stuff and fabric looking stuff.
Is there a “right” stuff to use for a vapor barrier in a crawlspace? (midwest, humid summers, cold winters, high radon).
jt8
“Real difficulties can be overcome; it is only the imaginary ones that are unconquerable. ” –Theodore N. Vail
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All I can say is I wonder about the fabric being a vapor barrier. If it's landscaping fabric or whatever other name it goes by, it slows the passage of liquid water, so I would think it wouldn't do much for vapor. As far as I know, the plastic whether clear, white or black is pretty much the same and would be best. If it were exposed to UV, as in an outside application, color may matter, but not in a crawl space. Sometimes the white stuff is sort of "prestretched" and laminated and is stronger--we used it to cover greenhouses when I worked at a landscape nursery. It's tougher, but I don't know whether it's needed where it's just sitting there as a vapor barrier.
If you are worried about radon, there are tests and if you have it, gravel and or pipes to collect it and vent it are necessary and for that I'm not much help. Fairly important to get rid of cancer causing gas, so if you have it, I would ask an expert experienced with it.
Tu-Tuff (sp?) which is white is a great product and quite durable, although somewhat pricey. Another nice thing about it is that glue and tape stick to it much better than regular polyethylene so you can really seal it up down there. I've had to buy it mail order - not sure if it is sold retail - I think just from the manufacturer.
If you want to same money, just use 6 mil black polyethylene. It is difficult to tape or glue though as it has almost a oily texture. Don't use clear because it degrades.
I've seen those rip stop plastics but have never used them so I won't comment.
Really though, the trick is to install the plastic when the house is almost done. That way, it won't get torn up by the workers (including yourself). Another thing that really helps is to grade the soil out as smooth as a golf course before the floor system goes on. It will make it better on everyone, and your vapor barrier will work out better too.
Also, do a search as this is an FAQ
Check out a product from Stego Industries. It appears to be very tough and impervious to water. I don't know about pricing as I am just investigating the crawl space sealing question myself. I is made in two thicknesses 10 or 15 mil.
Vapour barrier is always applied to the warm side. Period. If you use a solid material - plastic - under the insulation you will be trapping any moisture that permeates thru the floor. And you will have puddles on top of the plastic, as I can attest (in which case the remedy is to slash the plastic, or replace it as following...). Now, think of the floor components as being the VB itself, and a) either omit solid material and hold the batts up with strapping, string, or wire: or b) use tyvek, landscape fabric, or similar, to hold the batts up.
Radon and all the other 'scares du jour' should be retained by the groundseal VB laid either under the concrete or on top of a dirt crawl-space floor.
All the best...
To those who know - this may be obvious. To those who don't - I hope I've helped.
As another stated, Tu-Tuff is the way to go. This material is very thin, making is easy to place, you can buy it in any size; 100 foot lengths. Buy the tape from them also, same material, super sticky. I had a house with crawl space, severe moisture problem, mold. I ripped out the floor insulation, installed foamular on inside of foundation walls, tu-tuff applied from rim joist down. The home owners now use their crawl space to store extra clothing! It is bone dry. Tu-Tuff is great.
Do you remember if it was a vented or unvented crawl?
I think a FHB article had mentioned Tu Tuff. Is the stuff tough enough to walk (crawl) around on without damaging it?
jt8
"Real difficulties can be overcome; it is only the imaginary ones that are unconquerable. " --Theodore N. Vail
It was vevted originaly, but I closed it off and added ducting to condition the space.
The tu-tuff material is very strong, it cuts easily with a blade, but cannot be torn.
You can walk on it over dirt and sand, but if there are sharp rocks they can cut through. I layed down a piece of treated ply at the bottom of the stairs, then layed the tu-tuff, then another piece of ply. to creat a landing. My client layed pieces of carpet over the material to crawl around on.
Are you looking for vapour barrier (wall component in heated spaces) or a moisture barrier (under slab on grade)?
You mention radon gas, so I'm assuming moisture barrier under a slab. In that case you're looking for a non-breathable material that will keep moisture from the subgrade wicking up through the slab. Ditto for radon gas. Moisture and soil gas barriers are typically 6 mil poly and should have laps of at least 12" at joints.
Wondering if you or anybody else reading this has ever used Visqueen Ecomembrane in this kind of (or any other) application?Live light enough to see the humour and long enough to see change.
-Ani DiFranco
Are you looking for vapour barrier (wall component in heated spaces) or a moisture barrier (under slab on grade)?
Vapor barrier in a crawlspace under the house. Between the cool, damp earth and the house. No slab involved.
jt8
"Real difficulties can be overcome; it is only the imaginary ones that are unconquerable. " --Theodore N. Vail
The requirements are the same regardless of whether a slab goes on top or not. Use 6 mil poly and make sure the laps are generous. Some ballast on top such as gravel or sand would help keep it all in place.Lignum est bonum.