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which is best-dehumidifier or humid evac system

Posted by elle_2010 (My Page) on
Sat, Jun 26, 10 at 11:41

I have gotten quotes for three types of encapsulation systems and I don't know which to go with. First is encapsulate and use dehumidifier. Second is put in Humid Evac system with fan that sucks air from under the vapor barrier encapsulation at floor and vents it outside. No dehumidifier needed unless I insist on adding it. The third is remove all insulation on substrate and vent air from house into crawlspace and therefore heat and AC the crawlspace. Radiant heat vapor encapsulation would reflect heat and ac into area and it would then move upward again into house. Supposed to be energy efficient and gets rebate from gov't. My wooden floors are cupping supposedly due to high moisture coming from crawlspace - 79% in summer in NC. I am having them resanding and I don't want a repeat of cupping after I go through all of this moving out and expense. Air quality is not my main concern.It is humidity control under 50% and reduction of mold and moisture content in beams as Orkin refuses to honor my termite control due to 30% moisture in some beams. Which is the best for me? I do not want to dry out the floors too much as they cracked in half (65 boards) over the winter due to excessive lack of humidity once the heat came on in the house. (25%) So I have two problems and the floors are my greatest concern. Any advice? Also with using dehumidifiers in crawlspaces did anyone have wooden floors upstairs that dried and gapped and split when the humidity in crawlspace went down so much?

Thanks so much!!!!

Follow-Up Postings:

RE: which is best-dehumidifier or humid evac system

Building Science indicates that your third option--sealed conditioned crawlspaces--are the preferred method. This essentially makes the crawlspace an integral part of the home; it becomes a closed conditioned environment.

North Carolina has been the location of many controlled field studies in this method of reconstruction. For instance, see here.

Lack of humidity in winter only occurs in drafty, poorly insulated homes. Hence the use of humidifiers. In conjunction with your basement sealing, work on improving the air tightness of the above grade space.

Here is a link that might be useful: Lstiburek on Sealed crawlspaces

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