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We've read the threads on this topic before. We opted to keep our vents open. Now the crawlspace smells musty, and we're seeing some mold on items under there. I am starting to regret opting for a crawl rather than a slab.
Open in the summer, closed in the winter? That's how we've always done it. Unless you have a sealed crawl...which is totally different. Hope that helps. LOL!
I keep mine open year round. Mold is caused by moisture. Where is your moisture coming from? Do you have a vapor barrier on the floor of your crawlspace? Is rain coming in close to the foundation? Before you get rid of the mold, which is a sympton, find the cause.
The crawl is about 6 feet high at the back of the house. Not sealed. There is a vapor barrier on the floor. I don't see how rain could be getting in, as we've never had any yard flooding. We live on a very sloped lot so water does not sit. I can't say with certainty that the vents were closed in the winter though. I'll have to ask my husband about that. Now I guess the question is, once we find out why there's mold, how do you get rid of it? Thanks!
If it isn't rain getting into the crawl space, it is probably condensation from the hvac that is in the crawl space. If you closed the vents and the air didn't get rid of the moisture, that could cause mold.
To get rid of the mold, you can call the "mold people". They'll come in masks and spacesuits and charge you thousands of dollars! Or, call a handyman or a GC and have them get rid of it and pay a couple of hundred dollars.
I'm not sure WHY some people get it tested? I'd rather just get rid of it.
We just bought a home with a crawspace...never had one before...and there is just openings with wire covering them. There is not a way for us to close them. Should there be?
The moisture is coming in from the humid outside air through the open vents. Close and seal the vents, get a $100 dehumidifier, and set it at 50% humidity. Then you won't have any more moisture problems. It's that simple.
The crawl is about 6 feet high at the back of the house. Not sealed. There is a vapor barrier on the floor. I don't see how rain could be getting in, as we've never had any yard flooding. We live on a very sloped lot so water does not sit. I can't say with certainty that the vents were closed in the winter though. I'll have to ask my husband about that. Now I guess the question is, once we find out why there's mold, how do you get rid of it? Thanks!
Most high crawls show little mold development because they are so easy to ventilate and turn air over regularly.
The very low belly-crawl crawlspaces are much harder to ensure air turnover.
My opinion: Leave the vents open all year, at least for a trial.
You want to control sources of ground and surface water entrance.
Make sure your downspouts are not dropping water against the foundation wall. Some piping to deliver downspout water away is pretty easy to put behind shrubs, etc.
And since you are sloped, make sure the surface water is diverted away from the house by grading. There should be a build up of grade that slopes away from the house slightly to divert surface water.
There is a good chance that good ventilation and diversion of surface water will eliminate or hugely minimize your mold issues. Dry the mold to ambient humidity, and it is likeliy not going to do very well.
If not, or if the minimized results are not acceptable, you might go the route of a full vapor barrier, closing vents, and a dehumidifier, but I wouldn't spend that money without trying the free stuff first.
In winter the colder air is much dryer than in the summer. You want the crawlspace to be as warm as possible in the winter and as cold as possible in the summer. The ground will always stay a constant temp. so you use that to your advantage. When temps outside are well below 55 - 60 degrees F the ground temps will increase the air temps. In the summer where the temps are much higher the colder ground temps, the ground will cool the air.
Just to add you want to make sure your duct work is sealed and insulated if it's in the crawl space. You want to make sure all runs are as straight as possible. Find a way to measure surface temps by an instrument like a infrared thermometer and get a hygrometer that will relay dew points and you'll see very clearly whether open vents or closed vents are better in the different situations. Your location also makes a big difference on dew points.
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