I know this topic is better suited for another folder, but I wanted it to not get lost.
4′ crawl in SE New York.
Poured foundation, rat slab (cannot verify existence of vapor barrier)
There is condensation forming on the bottom side of floor insulation. Rat slab is mostly dry and I did find one vent of three open. Possibly one other that I have not gotten to.
Are near one vent seems damp to wet and I discovered a gutter leader right next to the vent that I believe may have been dumping water in.
AC ducts run through here; and un-insulated trunk with lots of “insulated” flex running off of it to the floor registers. Also cold water lines some ins some not with lots of condensation……….
I need to clean this up. I’m concerned about health issues. Mostly I want to stop the condensation and I will clean up the rat slab of any organic and absorbtive material.
What say you??
“When the spirits are low, when the day appears dark, when work becomes monotonous, when hope hardly seems worth having, just mount a bicycle and go out for a spin down the road, without thought on anything but the ride you are taking.” — Sherlock Holmes, 1896
Replies
Eric.
Turn your CS into a conditioned space.
Close the vents. Permanently.
Install a dehumidifier.
Drain the humidifier to the out side with a condensate pump.
Sounds like the insulation is installed backwards.
Paper vapor barrier should be to the living space.
Another option would be to cut some vents and returns in
HVAC trunks to move out the humidity.
Consider foam insulation on foundation walls.
......Iron Helix
Paper is to the floor. I wasn't clear on that. Condensation is hanging in little droplets off the FG.
I'm closing the vents for sure now. I'll close them and block them up with rigid foam and can foam.
I have the de-humidifier and was thinkining the same thing. Condensate pump into the waste line. I hesitate to do the ac thing as I am fearful the unit is already undersized.
This is a condo I am moving into. I have been in others in similiar developments and see the same ####, and the owners are oblivious. Seems like an industry waiting to be tackled. What a mess. I don't want to live over a petri dish.
"When the spirits are low, when the day appears dark, when work becomes monotonous, when hope hardly seems worth having, just mount a bicycle and go out for a spin down the road, without thought on anything but the ride you are taking." — Sherlock Holmes, 1896
I was back down there yesterday trying to clean up.
I've never seen anythink like it before The bottom 1 inch of insulation is wet, dripping; in some cases hanging or it has become so heavy that the whole batt fell out.
I cleaned up all the organic matter lying about that could hold moisture. Closed off the foundation vents at least temp.
Could all this condensation be caused from these vents? One was already fairly closed, one wide open and the other partially. The bulk of the condensation did seem to be concentrated near the vents.
The first floor ac flex ducts run through the basement. When the system is off, the warm moist air from the house drops down into the duct work............comments on this??
I need to get a dehumidifier down there with a condensate pump to dry it up hopefully.
"When the spirits are low, when the day appears dark, when work becomes monotonous, when hope hardly seems worth having, just mount a bicycle and go out for a spin down the road, without thought on anything but the ride you are taking." — Sherlock Holmes, 1896
Vents are bad, but so is a rat slab without a VB, and any negative slope around the foundation.
Protecting both the inside and outside of the ducts from condensation by sealing joints and wrapping with insulation would be a very good idea.
Dehumidifier w/pump is a great way to fix things short-term, but it gets expensive to run so fixing the cause of the problem, even if expensive, will pay off long term. Best, as I think was mentioned, would be to make it into truly conditioned space. There have been articles in FHB and JLC on how to go about doing that if you're interested.
Thanks Mike. I'm hoping I can dry it out and close the vents the problem will go away. I'm renting this place so I don't want to go for big bucks.
I understand conditioning the space, but have trouble wrapping my head around throwing my energy dollars down there.
I'd need a return air duct from the crawl space wouldn't I?
"When the spirits are low, when the day appears dark, when work becomes monotonous, when hope hardly seems worth having, just mount a bicycle and go out for a spin down the road, without thought on anything but the ride you are taking." — Sherlock Holmes, 1896
Ah, didn't realize condo=rent. In that case, make sure vents are sealed, downspouts are directed away from foundation, and run a dehumidifier.
Without installing insulation I wouldn't want to throw too much heat down there. More information here:
http://www.buildingscience.com/documents/primers/plonearticlemultipage.2006-12-05.5229931729/section-2b-recommendations2014air/?searchterm=sealed%20crawlspace
Thank you Mike!
"When the spirits are low, when the day appears dark, when work becomes monotonous, when hope hardly seems worth having, just mount a bicycle and go out for a spin down the road, without thought on anything but the ride you are taking." — Sherlock Holmes, 1896
I disagree with the 'seal it off' advice.
I think you will be better served by adding an exhaust fan, using a duct to draw air from the wettest or most remote areas. Such a fan would be automatically controlled by a 'humidistat.' You might also need to increase the fresh air that you can draw in.
That is, of course, assuming you have a 'humidity' issue. Do not overloor the possibility that the moisture is supplied from a leaking pipe (which might even be in the yard, uphill), or a ground water drainaige issue. Then those problems need to be addressed first.
Reno, your advice would make sense in your dry locale, but here in the great northern swamp, summer air is hot and humid. When it is drawn into basements and crawlspaces, which stay cool year-round because of cold winter temps, the moisture is drawn out of the air and condenses on any surfaces below the dew point of the air.
Installing a humidistat-controlled fan would just increase the rate at which the moist air is drawn into the basement/crawlspace, and would make the problem worse.
Good point about leaky pipes though. Definitely should rule that out before working too hard at the other stuff.
A difference between Reno, and (say) New Orleans? Why, you may be right! I confess to having got into the habit of seeing the world through desert eyes.
To be fair, I have lived / worked / crawled in many places that seemed proud of their humidity. Why, I even lived one summer in a place where puddles formed on garage floors due to humid air condensing water out. Even there, though, I can't recall any particular mold or mildew problems .... unless you somehow managed to completely seal an area.
I always understood that this was the reason for the plastic sheet in crawl spaces: to keep water out - and the vents were there to let any water that got in escape.
One house - this one in central Califirnia (which I admit is a fairly dry area) - had some 'moisture' and odor problems in the crawl space. I admit this house colors my understanding.
The odor, and some of the moisture, came from a sewer line that had rusted throught along the top edge. It was impressive; the leak almost looked like you had taken the pipe to a shop and had them machine a narrow slit on the top.
Most of the moisture, though, came as the result of this house being at the bottom of a hill. When it rained, not only did a puddle form in the back yard .... the crawl had a 2" sheet of clear water flow across the entire crawl space, where it exited the downhill side. This problem was solved by installing a French drain in the back yard, and giving the water an easier channel to follow. The results were impressive; after rain storms, the water shot out that drain as if shot from a fire hose!
If the source of the moisture really is moist outside air .... I wonder if anyone has deliberately routed incoming fresh air for their house through the crawl space, as sort of a 'natural dehumidifier?' Add a sump pump to collect the excess, and looks like you've solved a few problems at once.
Edited 7/2/2009 5:36 pm ET by renosteinke
"Earth tubes" are one idea similar to yours for low-tech a/c. Route a long pipe underground to bring in fresh, cooled air. Mold is a problem though.
Just plain sealing crawlspaces is no good, because moisture will find a way in one way or another. That's where the dehumidifier comes in, and ideally air sealing, duct sealing, insulation and a vapor barrier on the floor. They all make it easier to keep the air conditioned, once it's conditioned. In Eric's case he'll spend more for electricity but less for building improvements, but the end result should be similar.
It's getting better, alittle at least. When I left yesterday I stuffed the vents full of FG ins and left the ac on overnight.
This pm I closed off the vents with rigid foam board and can foam. When I opened on off the vents, my glasses immediately fogged over and it began to rain I believe!
Got the dehumidifier going, it suck over a quart of water out of the space in a little more than an hour.
Now that I have it cleaned up, I found a new problem as evidenced by the fresh "droppings".
BATS!
"When the spirits are low, when the day appears dark, when work becomes monotonous, when hope hardly seems worth having, just mount a bicycle and go out for a spin down the road, without thought on anything but the ride you are taking." — Sherlock Holmes, 1896
At least if you have bats you won't have mosquitos?!