Replies

1. 
   RichBeckman | Mar 06, 2005 07:39am | #1

   Toledo,

   From the stuff I've read, once the crawl is sealed, a vent with a fan should be installed to blow (usually condidtioned) air from the living area into the crawl.

   You certainly do not need central heat and air, but you are probably better off if you are blowing air from a room that is heated in winter and cooled in summer.

   Rich Beckman

   Another day, another tool.

1. 
   toledo | Mar 06, 2005 09:00am | #2

   Rich - so if you blow the air into the sealed crawl, it must go somewhere, somehow...back into the living area? I was wondering if it might be good to instead have a fan exhausting the crawl, with no vent from the living area...?

1. 
   RichBeckman | Mar 07, 2005 05:58am | #3

   " so if you blow the air into the sealed crawl, it must go somewhere, somehow...back into the living area?"As I understand it, if the crawl has been properly sealed, most of it ends up back in the living area through the multitude of holes that always exist between the crawl and the living area.But with the proper sealing of the crawl, there shouldn't be anything in the crawl air that you'd be concerned with.By blowing the air out of the crawl to the outside you are possibly putting negative pressure in the crawl. IF it is sealed correctly, this might not be a problem and, if powerful enough to counter the stack effect, will result in air moving from the living area into the crawl through the above mentioned holes.Where I am at in Indiana, the winters are cold enough that I would prefer to seal the crawl, insulate the perimeter and blow heated air into the crawl. In theory the floors will be warmer.Whether that applies to your location I don't know.I did have a guy from EFI (http://www.energyfederation.org/consumer/default.php) argue the point that the fan should blow from the crawl to the outside. He really started to get worked up about it really quick and, perhaps realizing he was a salesperson, quickly backed off saying you could do it either way.What's important is that the crawl is sealed off from sources of moisture and does receive some ventilation.
   Rich BeckmanAnother day, another tool.

1. 
   toledo | Mar 07, 2005 07:05am | #4

   thanks rich - this is a very nasty crawl I'm dealing with...only three blocks high, much of it below grade, unsealed on the outside, two dinky vents, 25 yr old...when I first went in, the subfloor was dripping and there were fluffy white formations covering many of the joists...and they left alot of sharp loose rocks all over just for good measure...

   I blasted a hole and stuck in a fan blowing out non-stop for a couple weeks now, and it's much better...

   so of course I want to dig the perimeter, seal the block, and french drain it; but the client's imaginary budget may not allow that - but if not, anything else I do will be if not worthless, then just ...worth less...

   so I go back and forth on sealing it or just venting it  like crazy, which choice is compromised by the plumbing running right  against the block...blah blah blah...

   add to this the client is extremely allergic to many things, and believes mold is the root of all evil, including cancer;  she will  not be living in this cabin, but ...maybe she will!  she doesn't know what she's going to do with it, making all the decisions piecemeal, reaking redundancy, sorry, now I'm venting...

   anyway, she passed on the CHA...hence, my question, hence your answer, hense my thanks...

1. 
   RichBeckman | Mar 08, 2005 02:40am | #5

   Well, if money is tight....Some crawls work without the sealing. Plastic on the floor of the crawl is a must, and the more thoroughly it is sealed the better, but...I've been in vented crawls where the plastic was just layed down and the seams sometimes even overlapped and there was no mold to speak of.The vents should be operable (can be open and closed) so they can at least be closed in the winter. Maybe they should be closed during the hottest most humid days, too. Maybe a sump pit and pump.I wouldn't offer any guarantees on doing it that way...sometimes it works, sometimes it doesn't (at least, from what I've seen).Best of luck on it.
   Rich BeckmanAnother day, another tool.