ventilating a crawl space

[BobSchrei]

Given:
- NE Ohio (large seasonal variations in temp, humidity,etc..)
- 20'X30'X4'h (2400 CF)crawl space in split level with direct access from utility room in lower level. Crawl space is under the living/dining/kitchen area.
- It has a gravel floor with a vapor barrier.
- masonry walls are insulated
- dehumidifier broke and am loath to buy a new one that simply recirculated must laden air.
- damp and musty smell is present.
Problem:
I have looked at the possibility of ventilating the space with an exhaust fan but am sensitive to a large loss of treated (heated in winter and cooled in summer) air if I ventilate too much. I thought of using a Humidistat to control and only run the fan to get the humidity to an acceptable level. Any recommendations?

 

[ChasBean1]

Hi Bob. I wouldn't get into any kind of control system for this. A humidistat might be of some sort of service but as Henry David Thoreau's philosophy goes, "man who make railroad must work to maintain railroad..." Okay, I mixed that with Confucious. Anyway, forget the controls and allow the space to naturally ventilate. Open windows and have louvers on opposite sides. If there are none, cut them in. Insulate between the joists with R-19 or better (preferably R-30), with vapor barrier on the house side. The below-gravel vapor barrier might actually be doing you a disservice in this application by trapping moisture. Crawl spaces are just like attics - if you're not storing your prescious baby photos in there, forget about it; it's an unconditioned space - separate it from your house and let it breathe. Good luck, -CB

 

Crawl spaces are rarely conditioned in any way...that's what makes them crawl spaces!!

As mentioned, leave this one alone, or at most, put some sort of space heater down there to keep your floors warm in the wintertime!

 

[BobSchrei]

Thanks for your help. It is an open space into the laundry room currently. The opening can be closed off though not easily that is why I looked into the conditioning. It is a basement, in effect though not in depth or function aside from storage.

I will at least close it off and vent it for now. winter may find other options but your views will work for summer. Spring is the worst when groundwater levels are up.

Thanks again.

 

find the source of the moisture and get rid of it.

you need to look at the drainage around your house, make sure the slope away from the house at all exposures are good. If not fix them. consider french drains
if the floor is not insulated ( you live in Ohio with no floor insulation - you only mention the walls ) them get them insulated. Ai (vent )r is good for the drier/ warmer summer months, do not recommend winter time air blown into the crawl space.