My house doesn't have a basement. Its 100% crawl space. Its damp and I layed a vapor barrier a few years ago.

Is a vapor barrier enough to prevent mold build up?

How do you determine if there is enough ventilation in a crawlspace? Its about 1600 sq feet and there is a vent on all 4 walls (about 6x12" vents).

Thanks,
Shawn

 

denverlynx,

You need 1 square foot openeing per 150 sq ft of floor space area. One such ventilating opening shall be within 3 feet of each corner of said building.

This is based on no mechanicals or heat ducts within crawl space.

Based on what you said, you need 11 sq ft of venting, appropriately placed of course.

Vapor barrier is good but in addition you need ventilation. Without it, mold conditions could be an issue.

Hope this helps!

 

Thank you for the information. There is heat ducts. But, based on your information it sound like my crawl space is vastly underventilated.

A friend suggested that I look into a power vent much like what is used in attics. But, I haven't been able to find such a thing.
Would this assist the issue.

11 sq feet seems like it could freeze my house over in the winter.

Thanks again!

 

denverlynx,

As I posted, when it is a heated or has heat ducts, this does not need ventilation as it is considered a heated crawl. The information about the heat ducts is helpful but you said that the area is damp. Are the heat duct insulated?

Adding additional vents in your area may not be good if we are talking about freezing temps. Is the crawl space insulated? Entire perimeter? This is one of the exceptions for having or or not having ventilation vents in foundation for crawl space - climatic conditions.

Normally poly is fine with proper venting. Installing a fan is an option but the code dictates that a cfm rating of 1.0 cfm per 50 square feet is required as long as vapor barrier is placed on soil. This would eliminate any additional vents that you may now have.

Confirm this with your local building inspector as I am using the IRC as a guide to your question.

Hope this helps!

 

Hi,

Thanks again for your time. Your answers have been very informative.

The heat ducts are not insulated. In fact, the only insulation in the crawlspace is the floor of the house. I had considered insulating the perimeter of the crawlspace/foundation. But, it was just too costly at the time. (the house floor is cold at times).
Anyway, I'm in Denver so freezing is a concern at various times.

Is it considered heated even though their isn't a vent in the ducts to transfer the heat into the crawlspace?

If I were to pursue a power vent or fan. Any ideas of what types of dealer would specialize in fans for attics?

Thank you!

 

denverlynx,

You're very welcome! I guess you could look at these links and see. Do some calculations on sq. footage of your crawl. You don't need much in this space as it will be less that a 50 cfm unit. I would personally go about a 80- 80 cfm but you decide.

http://www.alpinefan.com/venturi.html

http://www.efi.org/products/ventilat/ventline.html

http://www.positive-energy.com/pages...tionWall2.html

http://www.broan.com/

Like I suggested, call your local building inspector for advice on this before buying anything.

Hope these help!

 

denverlynx,

Sorry, 80 - 100 cfm unit, it's overkill but air movement required is very little to avoid problems. As long as there is a vent open to allow for air flow, this would do just fine. A smaller fan with all your vents closed may not provide enough air flow but you need to ask someone with more info on this and that would be the Inspector.

You want something quiet and that is not power consuming. Overall cost should be minimal.

Good luck and let us know what you found out.