Replies

1. 
   Andy_Engel_ | May 10, 2001 11:05pm | #1

   *
   I'd ask where you live. If it gets humid in the summer, what's to stop the humidity from condensing in the cool of the crawlspace? You almost certainly don't want the vents open in the winter, when they'd make your floor colder. In fact, I'm having a hard time imagining when crawlspaces should be vented.

   I've talked to a lot of people who are way smarter than me on this topic, and the consensus seems to be that you should treat crawlspaces like short basements -- Vapor barrier under a concrete slab, waterproofed walls and no vents.

   Maybe Bill Connor or Bill Rose will weigh in here. I suspect that both of them are more up on the current thinking on this topic than I am. In fact, you might do a search to see what's been previously said here.
   Andy

1. 
   Randy_Stukenberg | May 11, 2001 03:32am | #2

   *I am in N. IL. Summers can get pretty humid at times, but not constantly. Winters have been relatively mild in the past few years, which is not usual.

1. 
   Randy_Stukenberg | May 11, 2001 03:33am | #3

   *I am in N. IL. Summers can get pretty humid at times, but not constantly. Winters have been relatively mild in hte past few years, which is not usual.

1. 
   Bob_Walker | May 11, 2001 03:24pm | #4

   *Modern trend in northern-ish areas is to insulate the walls and conditions the crawlspace. Even with the rat floor, you need to control moituse down there.Ask local home inspectors what works best in your area. They're seeing and evaluating crawls every day.

1. 
   Gene_Leger_ | May 18, 2001 07:52pm | #5

   *Randy. Check the archives. There is a lot of information on crawl spaces. The consensus of opinion in the buiding science community is not to ventilate crawl spaces. Briefly, control exterior moisture by sloping ground aroud the foundation 6 inches in ten feet. Keep all flower beds, bushes, plants a minimum of 2 feet away from the foundation. Locate gutter down spouts on splash blocks and keep them a minimum of 2 feet away from the foundation.On the interior cover bare groud with a 6 mil vapor diffusion retarder (VDR). Run the VDR up the sides of the foundation walls and secure it to the walls with a piece of pressure treated 1x3 strapping. Insulate the walls and do not insulate between the floor joists above.If you have foubdatioin vents seal them up. If you live in hot himid areas or in climates with hot humid summers, ventilation causes the very problem it is supposed to solve. Bringing hot humid air (80 degrees F and 70-80 percent relative humidity)into a cool (50 degrees F)crawl space, the humid air will condense on the cool framing members. Hope this helps. GeneL

2. 
   Randy_Stukenberg | May 18, 2001 07:52pm | #6

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   Does a crawlspace need to be vented? I am using radiant floor heat for a shop 32x55. Cement cap on the floor.