# ductwork sweating



## TGMcCallie (Jul 21, 2011)

I noticed water on the plastic under my house.  I crawled under there and my metal duct work as well as the metal that is insulation wrapped is causing the water from condensation.  Under my house is well vented with all the foundation vents automatically opened.

What could be the problem and how can I correct  it/

Thanks


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## gatorfan (Jul 21, 2011)

Possibly counter-intuitively, the ventilation is your problem.  When the hot, moist air from outside under your house encounters cool surfaces (ground, ducting, floor), it is cooled and the moisture in it condenses.

Check out crawlspaces.org.  In general, the recommendation now is to seal off your crawlspace, insulate the walls, and install a vapor barrier on the floor.

Matt


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## paul52446m (Jul 21, 2011)

TGMcCallie said:


> I noticed water on the plastic under my house.  I crawled under there and my metal duct work as well as the metal that is insulation wrapped is causing the water from condensation.  Under my house is well vented with all the foundation vents automatically opened.
> 
> What could be the problem and how can I correct  it/
> 
> Thanks



The duct work should be sealed and the ducts need to be insulated with a vapor barrier insulation. Vapor barrier means ether vinyl or tin foil on the out side of the insulation. This insulation needs to be put on so its tight against the duct and all joints sealed with tape so no air can be between the insulation and the duct. You can put stove pipe wire around the insulation every foot and twist it tight to keep the insulation against the duct.   Paul


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