# Crawl Space Vents Confusion



## joecaption (Nov 30, 2011)

Unless you plan on making it a conditioned space leave it as is.
I'd remove the vents you have now and install automatic opening ones.
There about $17.00 each and take all of 10 min. to replace.
Then they will open when it's warm and close when it cold.
Any time I see a sealed unconditioned crawl space there's fungus on the floor joist and subflooring.
You do have 6 mil. plastic on the ground to act as a vaper barrier right?


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## Windows on Wash (Aug 30, 2011)

Read anyone of the myriad of threads on here about sealing crawlspaces.

Did the contractor that said to close them up and seal them recommend that along with other items or just that?

Did he say to do that just during the winter or as a general rule across the board?

If he said to do that permanently, run from that contractor.


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## Scully (Dec 3, 2011)

Windows on Wash said:


> Read anyone of the myriad of threads on here about sealing crawlspaces.
> 
> Did the contractor that said to close them up and seal them recommend that along with other items or just that?
> 
> ...


he said to install vapor barrier and permanently seal the vents in crawl space. this is what he quoted me for:

install 6 mil vapor barrier to ground in crawl space and drape up wall and secure to wall: $777.00 

Air seal: foam 3 vents shut in crawl space in basement:$175.00


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## Windows on Wash (Aug 30, 2011)

Does he plan on insulating the crawlspace wall too?

You need to if you convert it to a conditioned/sealed crawl to do it right.


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## joecaption (Nov 30, 2011)

All things any DIY could do for less then $100.00 or less in materails.
And a few hours time.
Inless someone also adds a way to heat and add A/C to this crawl and insulate the walls it's a waist of time and money to block up the vents.


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## HomeSealed (Jan 3, 2008)

Okay, I'll fill in for Gary here: http://www.buildingscience.com/documents/information-sheets/crawlspace-insulation/ :thumbup:

That number quoted above is utterly ridiculous as is amount of time necessary to properly treat a crawlspace. Joe, what are you insulating/sealing the rimjoist with in your $100 quote for materials? :whistling2:

Scully, as WoW mentioned, if he is sealing the space (which IS recommended in most cases) the cs will need to be insulated (walls) and air-sealed as well. Pricing is subject to a bunch of factors, not the least of which is the size of your space. If that info that you copy and pasted is the entirety of the quote that you were given, you probably want to find a different contractor. His scope of work is incomplete, and his description is vague to the point of being unprofessional.


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## CrawlSpaceMoist (Nov 24, 2011)

While I'm a huge fan of sealed crawl spaces ... did he say WHY to seal the vents? Did he take moisture readings in the joists? Fungi? poor insulation or any other signs of high-humidity problems?
Fact is, if your crawl space is okay, you don't NEED to spend the money to seal and condition unless you're looking for the environmental and efficiency improvements.
I would avoid the automatic vents, though. The purpose of a vented crawl is to clear out the humidity in the crawl. Auto. vents are temperature sensitive and open or close regardless of how poor the humidity level may be in the crawl. On cool days you can have them closed and have amazing problems beneath the home. Better to be aware of what's going on beneath your home and open/close vents manually.
Finally, you didn't mention where your house was... that could help with the advice. or square footage of home. or size of crawl, conditon, etc.


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