I have two sump pumps in my crawlspace. They work very well in the winter to clear water that seeps in from outside the house. Of course, the ground remains wet/damp the rest of the year though. I have been advised to install a forced air system to dry out the crawlspace and prevent any mould from appearing. Can you advise as to who makes such a device and how best to install (on blocks to keep clear of water in winter?)?

 

If the ground is consistantly damp the water table is not to far from the surface and dampness may always be present. Does the crawl space have sufficient ventillation? A minimum is approx. one square foot for every 300 square feet of crawl area. Try fans in the wall openings to get air movement, or a dehumidifier sized for the area, You might consider a vapour barrier attached to the bottom of the joists to reduce dampnesss from entering the house

 

quote:<HR>Originally posted by gregsnod:
I have two sump pumps in my crawlspace. They work very well in the winter to clear water that seeps in from outside the house. Of course, the ground remains wet/damp the rest of the year though. I have been advised to install a forced air system to dry out the crawlspace and prevent any mould from appearing. Can you advise as to who makes such a device and how best to install (on blocks to keep clear of water in winter?)?<HR>

I had the same problem with excessive air/ground moisture under my house here on Albemarle Sound in coastal NC. I solved it with an exhaust fan that I built into a new crawlspace door. I contacted W.W. Grainger tech support to determine the size of fan that I needed, and stepped up to the next size. It runs 24/7 on a little 1/30th hp motor (except for freezing weather)and keeps my crawlspace bone dry, and uses zilch electricity.
A. Determine cubic footage of crawlspace (heightXwidthXlength).
B. Get louvered fan to handle air exhaust for cubic footage (I went with a ten-inch 580 cubic-ft-per-minute fan, although Grainger said that 250 cfm would do for me).
C. The housing needed a 14" square opening on mine. I built a new crawlspace door of pressure-treated plywood. I put one layer of p-t 2X4 on outside of door covered with screen and hardware cloth to keep out "guests".
D. Put two layers of p-t 2X4 on inside of door around opening (the 3 layers of 2X4s and the 1/2" plywood are for the louvered fan housing clearance).
E. You can hook it up to a humidistat or a thermostat or just plug it in direct and let it roll (which is what I did).The fan costs about $130.
It works so well that my heating & air people borrowed my "design" and have given it to a lot of their customers with the same problem. Works like a charm! Good Luck!