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Do you use insulation with a vapor facing in the ceiling in humid areas?

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Posted 2013-05-13T02:38:15+0000  by bushman bushman

In most places where it is cold, water vapor is created within the home, and it always moves outwards towards the colder drier outside.

In hot humid places, depending on the time of year it moves inwards or outwards, depending on which side the heat is.

If you have your air conditioning turned on, it is colder inside the home and the sun drives the water vapor inwards towards the cold inside.

When it is colder outside than in - the water vapor moves outwards.


Sheet polystyrene is waterproof and if thick enough, water vapor proof.


Cover your frame with three inch thick polystyrene, making sure there are no gaps or cracks for the water vapor to slip through.





Posted 2013-05-18T19:51:43+0000  by Anthony525

 what the best insulation to use in a crawl space with concrete floors and possible moisture issues?

Posted 2013-07-12T22:21:20+0000  by keithsue

There is no point in insulating a crawl space.

The movement of heat is from your living space into the crawl space.

Your comfort zone is always going to be warmer than the crawl space.

Therefore insulate under the floor and keep your joists and floor warm and dry.

There is no point in treating the crawl space for water vapor infiltration as again water vapor moves from warm to cold.

If you live somewhere where it is cold in winter, then the movement of water vapor is always going to be outwards.

During the summer the heat of the sun forces the water vapor into the crawl space, during the winter the heat inside your home moves the water vapor outwards through the walls, floor and ceiling - if the water vapor has easy acccress to the outside through thousands of holes, no problem. If it is trapped inside the walls or roof, that may lead to a problem.

Water vapor enters and leaves a crawl space all year round - without harm.

Posted 2013-07-13T12:56:37+0000  by Anthony525
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