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  1. #1
    Join Date
    Feb 2014
    Location
    Saratoga Lake NY
    Posts
    1

    Default Lake house/crawl space and H20

    Hello, looking to get some advice regarding crawlspace insulation.
    I think my situation is a little different because the water level under the house raises to about 4-5" sometimes during the warmer months especially around spring time. I'm located in the northeast.The type of dirt is a clay/shale base around my foundation.
    I own a home about 200 ft from a lake. It was built in the 50's and I rebuilt it in 2000. I added stone to the 4ft high dirt crawlspace then. That was a job. Wheel barrel and a ramp. It was 13 years ago but I still remember it well. The crawlspace has been closed off sense. But I tried venting it, I have fans down there to circulate the air which I think made the musty smell a little worse. In 2002 insulation batts held up by wire were added to the floor but hasn't done really much good. I can tell this winter it has been very cold.
    In 2004 I switched to forced hot air heading from hot water and the duct work was run under the house in the crawl space. The duct is insulated but I smell the musty smell in the summer months probably through the new ducts.
    Options are to encapsulate with plastic. I've read where people have a smell they can't get rid of after having that done.
    Also there alot of firms in that business that don't do a good job and once it's done wrong, it's done.
    Pour cement with plastic under it and add a sump pump but the pump might run all the time, and not so sure the water will not seep though the walls. I have gutters and the ground yard is slopped away from the house pretty good.
    (Spring time you can dig down a foot anywhere in the yard and hit water.)
    Next to spray foam the floor between the crawl and living area and leave the rest alone. Does the still water harm the foundation over time?
    I'm going to put another addition on to the house one more time and I want to get this problem taken care of now.
    I've posted on a couple other forms and didn't really get an answer. Is there anyone from the northeast or anywhere else with the same situation?
    If you have any questions please feel free to ask, I want as much info. as I can get.
    Any help would be much appreciated, thanks.

  2. #2
    Join Date
    Dec 2013
    Location
    New Hampshire
    Posts
    27

    Default Re: Lake house/crawl space and H20

    Even if you have 5 inches of water in your crawl space due to poor drainage or a high water table; the musty moldy crawlspace problem may be cause by the intrusion of high outside humidity into the relatively cool crawlspace just as it is in well drained crawlspaces.

    Standing water won't cause much of a mold problem if it is kept cold as in a root cellar or if the crawlspace is very well ventilated to outside (greater than 1 sq. ft. of vent for every 150 sq. ft. more if much below grade) Small to intermediate levels of ventilation in deep crawlspaces causes some of the worst mold and rot problems. Venting to outside makes for less efficient heating system, freezes pipes, and freezing water in a flooded crawlspace could damage the foundation. For standing water to not cause mold it must be about 7 degrees colder than the wood or other surface that mold might grow on within the same confined airspace.

    For the cold crawlspace or root cellar approach any air leaks in the floor, foundation walls, and ductwork are sealed. Sealing is very important for keeping out summer humidity. The foundation walls are insulated to R-10 to 15. The floor is insulated with insulation on the underside of the joists R-3 to 13. (Insulation between joists will make mold problems worse in a unvented crawlspace) If there is vinyl flooring or a plastic vapor barrier under the flooring; no foil or plastic vapor barrier should be on the insulation. Wood or any mold prone materials below the insulation should be removed or replaced with masonry or pressure treated. This might not be a very effective approach if the ductwork isn't well insulated. The structure of the house will be free of mold but the crawlspace will be damp and smell earthy.

    In a warm crawlspace approach no insulation is used in the floor between or under the joists. The foundation walls are insulated to R 10 to 15. And the ground is sometimes insulated to R - 3 to 5 or a dehumidifier is sometimes used. The insulation on the ground helps keep the space above well above the dew point and the ground below cool enough to absorb humidity out of the air in summer and cool enough in winter that evaporation is limited. To allow the ground to absorb moisture no vapor barrier should be used with ground insulation.

    With a warm crawl space approach the standing water should be illuminated. Puddles of water will create more work for a dehumidifier. Though not as much as an open vent to outside. If water should flood in on top of the insulation on the ground it will readily get warm enough to evaporate and cause problems.

    Sump pumps can't keep up with a high water table in corse sand or gravel soils but a reasonably sized pump can often work well in clay. If you have enough slope it's better to cut a ditch and run a drain by gravity to the surface. Or you could fill in the crawlspace until it is above the high water table.

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