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I've owned several houses with crawl spaces, but only recently have I heard of doing this.
Background: I currently own a small 80 year old house which is built on a crawl space. Foundation is typical pier and beam with a complete concrete perimeter foundation. There are some minor drainage issues around the house that could permit water to get into the crawl space through the side vents, but I am having those corrected.
My family has owned this house for over 40 years. As far as I can recall there were never any mold/mildew/musty smell issues until just recently when as noted above there was some water ingress due to perimeter drainage issues.
Once the drainage issues are fixed and the crawl space is good and dry, would there be a value in putting a vapor barrier in the crawl space, and what would be the advantage? Do you lay it right down on the dirt, and if so, how do you work around all the piers in the middle? If it's lying on the ground, do you screw it up when you go under the house and slide around for repairs? How do you get to the (relatively) few things that are in the dirt (like drain pipes) if you need to, do you just cut it and then tape it back together? Would it make more sense to staple a vapor barrier to the undersides of the joists?
It makes sense like wearing your seat belt makes sense. One more layer of "just incase" protection.
The real question is do you stick with the older way of doing things (~90% coverage, just laying on the dirt, edges loose) or with the most modern way of doing it (100% coverage, up the walls/piers 36", taped completely, all "vents" blocked off. Read up and decide for yourself. I noticed a major difference by shifting from the older way to the newer way (had a lot of condensation that went away) on my 1930's built house.
Deciding the above will dictate the Rest of your questions. But generally speaking, if you slide on the plastic it doesn't really go anywhere, even when loose. If you need to get under the plastic, you either fold back and edge or cut through. Piers and walls are just cut around and as for just stapling it to the joists, seems like that would add significantly to both the install and the typical kinds of repairs you'd do from under the house (most stuff is off the ground). I don't know if it's better or not, never bothered to ask when absolutely everyone puts it on the ground.
The current preferred method is to completely encapsulate the crawl space, effectively making it part of the conditioned space in your house. That means closing off the vents and installing a sealed vapor barrier. This is more important if your ducts are down there. 6 mil reinforced poly is sufficient, but if you anticipate using it for storage or frequent repairs, heavier sheeting is better. Like Brian_M said, doing it right involves taping all the seams, and sealing it up the walls and piers. This is not cheap, as in thousands of dollars.
Laying loose poly on the ground, with the seams overlapped 12" is better than nothing, and can be done for hundreds instead of thousands.
Having said all this, if you're not having any issues, you have the option of doing nothing. A lot depends on where you're located. The biggest culprit for mold is high humidity and hot weather. There's a lot of information out there that can help you decide what's right for your situation.
I've owned several houses with crawl spaces, but only recently have I heard of doing this.
Background: I currently own a small 80 year old house which is built on a crawl space. Foundation is typical pier and beam with a complete concrete perimeter foundation. There are some minor drainage issues around the house that could permit water to get into the crawl space through the side vents, but I am having those corrected.
My family has owned this house for over 40 years. As far as I can recall there were never any mold/mildew/musty smell issues until just recently when as noted above there was some water ingress due to perimeter drainage issues.
Once the drainage issues are fixed and the crawl space is good and dry, would there be a value in putting a vapor barrier in the crawl space, and what would be the advantage? Do you lay it right down on the dirt, and if so, how do you work around all the piers in the middle? If it's lying on the ground, do you screw it up when you go under the house and slide around for repairs? How do you get to the (relatively) few things that are in the dirt (like drain pipes) if you need to, do you just cut it and then tape it back together? Would it make more sense to staple a vapor barrier to the undersides of the joists?
You've seriously never heard of a vapor barrier in a crawlspace?? You gotta be kidding?
You've seriously never heard of a vapor barrier in a crawlspace?? You gotta be kidding?
Well, the three (not actually "several" as I said above) houses I've owned with crawl spaces were built in 1936, 1939, and 1950. No one ever saw any need to modify the crawl spaces from the way they were built. I never had any issue with a crawl space till this last issue with water getting in (as noted, I've got a plan for making sure that doesn't happen again). Given that, why would I have launched into vapor-barrier-in-crawl-space research before now?
Does that mean you Also don't treat for termites/wood boring beetles? Because vapor barrier is an essential step in that process too.
I think the shock comes from your admission of owning several homes and not doing rudimentary research on how you can best maintain that home so problems don't arise that will cost you $$$. Nevermind not having one single home inspection done where the inspector pointed out the lack of vapor barrier, and I shudder at the thought of you skipping an inspection based soley on this thread and your admission of "why would I need to know that" philosophy. But hey, you've been lucky. Good for you, probably want to buy a few lotto tickets as you never know how that luck will play out.
Does that mean you Also don't treat for termites/wood boring beetles? Because vapor barrier is an essential step in that process too.
I think the shock comes from your admission of owning several homes and not doing rudimentary research on how you can best maintain that home so problems don't arise that will cost you $$$. Nevermind not having one single home inspection done where the inspector pointed out the lack of vapor barrier, and I shudder at the thought of you skipping an inspection based soley on this thread and your admission of "why would I need to know that" philosophy. But hey, you've been lucky. Good for you, probably want to buy a few lotto tickets as you never know how that luck will play out.
1) Of course I treat for termites/wood damaging insects, if the need for treatment has been shown. The one house I currently own with a crawl space was bought by a member of my family in 1973. I am certain there were no crawl space vapor barriers in 1973, and certainly not when the house was built in 1939. That house, by the way, has no termite issues. The termite inspector I brought out to the house indicated that the house was probably treated in the 1960s or 1970s with chlordane, which has a persistence of more than 50 years.
2) The other houses noted were purchased in 1964 and 1988. I don't know what kind of inspections were done in 1964. In 1988 there was no note of vapor barrier in crawl spaces.
And no, I do not spend all my time trying to figure out what might go wrong when nothing has gone wrong. Now that something has (water ingress to the crawl space) I made what appears to be a mistake - asking for some general background information on vapor barrier in a crawl space. It appears to have been a mistake due to the nature of the comments. However, you know as well as I do that if I call businesses on this issue, all I'll get is a bunch of sales pitches.
Is the climate where you are at fairly dry? Is the moisture from heavy, frequent rain or irrigation?
Did regrading help reduce or eliminate water intrusion and/or the dampness under the house. You seem to think the crawl space will be "good and dry" when the exterior is addressed- if that happens, even when it rains, then you don't need a vapor barrier.
If the moisture is unavoidable after you have regraded then you should research how to approach reducing the moisture under the house and a "vapor barrier" may be a part of that. Sometimes water comes in via cracks or gaps in the foundation or vent openings etc...sounds like you are on the right track and doing stuff to make it better Please let us know how things go!
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You gotta be kidding?
