Thread: Crawlspace Dehumidifer

What are the pros and cons of this application in the crawl space?

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In my area of the country crawl spaces are required to be vented. If you used a dehumidifier in a vented space it would just run all the time....and have to be huge to have any effect. The utility company may love you.
The trend in crawlspace design is to seal it up and treat it like a conditioned space. I've seen some serious moisture damage to buildings from crawlspace conditions. The new 'building science' promotes pouring a concrete floor, not designing with outside venting, insulating, subsurface moisture control, then conditioning the air just like the air in the living space. With retrofitting, anytime you can approach this design the building will thank you for it. In some cases it may be pretty expensive but if there's a real moisture problem that may create even greater expense.

PS...I graduated from Summerville HS in 1970.

Todd,
Steve nailed it. Building Science now recommends crawl spaces to be conditioned spaces sealed off from the exterior just as tight as the rest of the living space, insulate the walls, seal the floor, add ventilation. Yes that may entail use of a dehumidifier, but the whole key to keeping the space dry is keeping the water away in the first place and that starts with gutters and down spouts directing roof runoff well away from the foundation as well as positive at foundation grading again directing all runoff well away from the foundation/ crawl space. "water always wins" just keep it away.
You will find that doing so will drastically reduce the run time on your dehumidifier. Up here in WI. we have 8-9' deep basements and 4' crawl spaces and I have, many times improved roof drainage and runoff around a house and within a year or two cut the dehumidifier run time down to next to nothing. It works. The added bonus of a conditioned crawl space is warm floors.

Jim Weyenberg
HouseMaster Inc.
Senior Inspector
2006 HouseMaster Inspector of the Year
920-309-3410