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tomandlu 01-15-2008 07:03 PM

Crawl Space - to vent or not?
Situation: I'm looking at a 1940 house in NC in near the Smokey Mountains. It has a stone foundation. The crawl space is dry although there is evidence of previous termite infestation (not active). We are going to be doing a lot of work to replace/reinforce the floor. The inspector suggested putting in vents. I've read a lot of conflicting information about vents - that they just make things worse and the whole theory of installing vents was wrong to begin with. I'm not sure. It is going to be an ordeal to put in a couple of vents - can do it, but not the 6 or 7 the inspector recommended. Or an exhaust fan. Or a dehumidfier. What would be best?

1940 840 sq ft home
Rock foundation, 4' high, no vents.
NOT airconditioned; winter time has baseboard electric heat.
Climate is warm and humid in summer (NC - near Smokies).
dirt floor in crawl space.
1. punch in two vents (that is doable as there is an old window and a place in the rock that has since been filled in)?
2. open vents in the rock and add a fan to move air around in the crawl space?
3. add a vent with an exhaust fan?
4. Close up crawl space and add a dehumidifier? (this is an old house w/lots of 'ventilation' - not tight new construction - would a dehumidifier really do the job?)
5. ???

What is the right approach for an old house in the high-humidity summer South?

AtlanticWBConst. 01-15-2008 07:12 PM

Vents are required in crawl spaces by code in my region. The vents should be installed in such a way as to create a "cross-breeze". They are primarily advantageous during summer months when hot, humid (moist) air exists. The point is to get this air out of your crawl space. During winter/colder months, when air is dry, vents should be closed off.

AtlanticWBConst. 01-15-2008 07:23 PM

Here are pictures of an addition we built with a crawl space foundation.
We installed a vinyl lovered vent that could be shut in cold weather. On the other side of the addition, we installed awning-style vinyl basement windows that the Home Owner planned on leaving open during warmer months and closing off during winter months. These created an acceptable cross breeze for the crawl space during summer.

Closed Vent:

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