Some would say that any amount is too much.

     I would argue that most have some amount of water----even if it is condensation trapped under the ground cover----where the effect it could otherwise have on the house structure is minimized.  Many crawl spaces show signs of past moisture----with high water marks on the foundation and other structures, while others have actual standing water in them----sometimes even on top of the ground cover.

     It is very important to the health of the home to control these moisture levels.  The high water line in this crawl space is pretty obvious----and may actually date to the time of construction.  The hole in the foundation at the center of the picture is a "gravity" drain that was installed to drain the crawl space during construction----before the roof is installed----to prevent the "swimming-pool effect."  These drains can just as easily flood crawl spaces from the outside if exterior water sources aren't controlled properly.

     In this next picture the high water mark visible on the chimney (and on the support post to the left) happened since original construction.  The water would have been at least 5 feet deep-----most likely accounting for the new water heater visible in the background. 

     Take a look at this next picture.  The grey "socks" on all of these support posts are stains from long standing, but seasonal, flooding----perhaps every winter this crawl space is a swimming pool.

     When conditions in the crawl space get this bad, in this neck of the woods, it can be a big problem.  Water evaporates----they call water in this state----"water vapor" (a gas).  As the water vapor rises through the home it condenses back into water on the first surface it reaches that is cold enough.  This might be windows in the living space or the roof sheathing in the attic.  When this happens in the attic, the roof structures can be destroyed worse than structures in the crawl space itself.  In this next picture you can see how all of the roof sheathing is black with fungal-growth-----mold----even right next to the vent.  Even in well vented crawl spaces and well vented attics, this much water in the crawl space is going to be a problem for the house.

     Too much water in the crawl space is never enough----it is too much.

Charles Buell  

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