I have never seen this before and was hoping for some insight. This crawlspace has a vapor barrier on the floor and then a house wrap attached to the floor joists throughout. The crawlspace had a ton of moisture throughout, including condensation holding on the house wrap. Super hot day here with a good rainfall during the inspection, with all of the vents closed. I did not see any obvious signs of water intrusion. I have a pretty good write-up for this but I wanted to get a better handle on what is causing this? Is this unusual system just holding a ton of moisture in the crawlspace with the added issue of limited ventilation, possibly?
The crawl needs air movement to keep it from becoming a musty, sweaty, moldy, pit. In your area, best practice might be to vent it to the outdoors. In my area, best practice is to treat it as the indoors and condition it the same as the living areas.
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Well, it is not a vapor barrier so it is wrong from the start. DYI encapsulation. Not a big deal if moisture was not an issue, but I bet it was a problem and still is.
Edit. Do I see a vapor barrier on the dirt floor and house wrap attached to the underside of the overhead floor structure? If that is the case, I see little consequence, unless they are hiding something.
The vents should be opened.
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Opening up the crawlspace vents may not help…
“…ventilation air in the summer months in most parts of North America brings moisture into crawlspaces and deposits this moisture on surfaces that are below the ventilation air dew point.”. - Joseph Lstiburek
If there is floor insulation above that house wrap, that could be the problem. See this article for details:
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There are a lot of topics on this issue. Your floor vapor barrier looks to have quite a few holes in it. The wall has efflorescence and has no vapor barrier. My guess is that a lot of moisture is entering the CS from those sources. IMO, that is the issue at hand.
Housewrap under the floor joists is acceptable within my current level of building science knowledge. It’s not well installed and not sealed, so my guess is the floor insulation has high moisture and possible condensation.
Do some internet research: Should Crawl-Space Vents be Open or Closed? - This Old House
I just finished an inspection with a vented cellar with a dirt floor and no moisture control. Large open vents present. Water drops on the joists, rotted floor joists and subfloor. Not a nice place to be. I recommended full encapsulation of dirt floor and masonry wall along with closing off the vents.
Edit: CS moisture conditions like this can result in cupped wood flooring or other moisture related floor issues on the main level. Keep an eye out for that issue when the CS has high humidity. I’ve seen these secondary issues many times.
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That was my thought after looking at the main beam, it looks like moisture has gotten into it.
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I agree. Here in GA insulation is almost always a mess for the reasons noted in the article you posted.
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The problem is that it’s not like the exterior-vented crawl area is air tight to the outdoors typically. So, the air in the crawl will be roughly the same temp and dew point as the outdoor air. Opening the vents allows air movement, which helps dry things out.
They also make a variety of vent fans to help with air movement.
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Morning, Tom. Hope to find you well.
Totally wrong process to prevent moisture management infiltrating the habitable space.
Installed is/are, two layers of (WRB), Weather Resistive Barriers. WRB’s are installed on the exterior of a building’s wall. Not crawlspace cavities. WRB’s prevent liquid water, referred to as Bulk Water, from infiltrating the wall assembly, while allowing water vapor to escape.
Vapor barriers considered impermeable, with a perm rating of 0.1 or less, considered impermeable, placed on the ground of a crawl space, and sometimes up the walls to prevent moisture from seeping up from the ground into the crawl space, would be the proper barrier.
Refer to a crawlspace encapsulation contractor for further review and updating and to act upon any recommendations therein would be my referral.
Just my wag..
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That’s a problem.
Even though the house wrap is a moisture barrier as opposed to a vapor barrier, if there is insulation installed between the floor joists, it’s most likely wet and could be cause structural damage. I call out insulation whenever I see it installed between the joists because 95 percent of the time it’s wet, full of mold and falling down.
Here is the note I put in every crawlspace I inspect unless it’s already encapsulated and has adequate air movement.
The building science concerning crawlspaces has changed over
the years. The crawlspace should be considered as part of the
house, so what is in the crawlspace is also in the occupied areas of
the house. Best practices today recommend crawlspaces to be
encapsulated, the exterior walls insulated, and the air to be
conditioned.
Here’s a good video on the subject.
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Oh My, that’s a problem!
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I concur big time. I would/could/can only imagine what nefarious moisture vapour conditions the flooring and structural assemblies are under.
Again, I concur. I can only imagine, without visual, lite mechanical probing, an awl or pointed steel object, and measurement equipment readings, a hygrometer and a moisture meter, the atmosphere in that crawlspace can contribute to the deterioration or/and failure of a structure’s integrity.
You are being modest. I would say this is one of the best home science videos on creating the perfect crawlspace environment I have seen to date. A must watch for anyone interested in crawlspaces.
Kevin…“You’re The Best!”
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Agreed. Did he add that important observation at a later time?
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Great Post from the BSI.
Jim MA EHS, CPI, IAC2