Foundation Vents

[mcp6453]

My home is in central North Carolina. A friend told me recently that many new homes do not have foundation vents. What's the story? Vents or no vents? Should I seal mine off?

[Sonny]

I suppose the floor area under the house is bare soil, i.e., the crawl space. I think, in the cases of no vents, a moisture barrier (lots of visquene) is placed on the ground, to keep the moisture/excess high humidity from rising from the soil..... Making sure the soil is sealed off well.

You might not want to permanently seal the vents, but just close them off (after the visquene treatment). If you would ever need to ventilate the area, they would still be at your service.

I'm several states away from you and your scenario is not applicable, here, but my sister is near Statesville, NC. Her new home has no vents and has visquene laid in the crawl space. You might want to speak to a contractor to make sure my reasoning is correct or not. Most of her crawl space is about 4'-5' high, so one can walk around, in there. Her water heater is there, as is very easy access to heating/cooling duct work, plumbing, dryer duct (to outer wall. The dryer moisture is not vented into the crawl space), etc. I'm no contractor, but when I visit her, I give those utilities an inspection, for her. The visquene makes for a relatively clean work area, under there, also, rather than working on bare soil.

[Robert Neville]

Absolutely! Closing off the foundation vents is about the worst thing you could do for mold. It's not moisture rising from the ground, it's also from moisture in the house.

[willshak]

mcp6453 wrote the following on 3/1/2012 6:40 PM (ET):

The new houses probably have poured concrete floors in the crawl spaces, just like a regular full height basement. They do here where I live.

[krw]

Most of the houses I've seen around here have dirt of gravel crawl space floors. A guy down the street (mine's on a slab) had a river flowing through his and had to put many more tens of yards of gravel underneath. Even with a concrete floor, it isn't impervious to moisture. I'd still want vents. The consequences of mold are just too bad to play around with it.