How do I Choose the Best Crawl Space Dehumidifier?

Norma Jean Howland

When you have a crawlspace, it can be challenging to keep it dry. A crawl space dehumidifier, however, can help control moisture and protect your home. Choosing a dehumidifier that is specifically designed for a crawl space may be a good idea. To choose the best option, look for a unit that is smaller in size and able to run in cooler temperatures; it also may be wise to find a model that has some sort of built in pump for automatic water removal. In order to make the most of your crawl space dehumidifier, it is important to get the right size for your space as well. You may also want to consider purchasing an energy-saving unit, as dehumidifiers tend to use a fair amount of electricity.

A dehumidifier may help control moisture in a crawl space.
A dehumidifier may help control moisture in a crawl space.

A crawl space dehumidifier usually tends to be more compact in size than those designed for use in the home. You may need to measure your crawl space in order to ensure that you get one that is the right size and has enough capacity to keep the area dry. Generally speaking, dehumidifiers are sized according to how much moisture they can remove in a 24 hour period. Another consideration that may affect your decision, is just how damp your crawl space tends to be. If you have a very wet area under your house, you may need a larger unit because there will be more moisture in the air to remove.

Dehumidifiers can help prevent mold growth.
Dehumidifiers can help prevent mold growth.

Unless you want to go down into your crawl space on a regular basis, you will probably want to get a crawl space dehumidifier with an automatic pump. Since most dehumidifiers will shut off when the bucket is full, a pump will ensure that your unit is working as needed, making those extra trips into the space unnecessary. The pump, which has a drain hose connected to it, will pump water outside into your yard. The hose can be snaked through a vent, window, door, or discharged into a sink drain if you have one.

Operating a crawl space dehumidifier does use a bit of electricity, so buying one of the energy-efficient units may make the most sense, especially if you are working within a budget. To save energy, some models have an option that will let you adjust the unit to different levels of dryness, to accommodate fluctuating humidity. These units sometimes also offer a floating switch, which will empty the bucket only when it is completely full to prevent the unit from continuously pumping.

Toxic mold can grow on any porous materials stored in a crawl space, including wood, leather and textiles.
Toxic mold can grow on any porous materials stored in a crawl space, including wood, leather and textiles.

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Discussion Comments


@Iluviaporos - You can actually get pretty economical dehumidifiers. And some people don't have to worry too much about electricity costs, either because they don't pay much for it, or they generate their own.

I agree that crawl space waterproofing is important, but I think people should consider all the options.


@KoiwiGal - I wouldn't mind the idea of it turning itself off when full though, since I think I would be very expensive for it to be running all the time.

If I was going to do this, I would first make sure I'd done everything possible to reduce moisture in the crawl space. Insulation is a good idea for a lot of reasons and can also help to reduce moisture if you install it properly. You might also want to try and fortify your foundations against moisture by painting them or sealing them. Then, I would figure out the cost of running the dehumidifier and I would get one that could work on a timer so that I could control how often it would turn itself on.

I can definitely see how it would have long term benefits, but you'd really have to see whether the expense of running it all the time was going to stack up against the potential savings from running it. I'm sure in a lot of cases crawl space dehumidifiers are not actually worth it.


You really will need to get a crawl space dehumidifier that has an automatic pump connected to your waste water line, or you will have to essentially empty it all the time.

When I have a dehumidifier for my room, it tends to fill up very quickly and I think there would be much more water in crawl space air than in a bedroom.

Of course, it depends on where you live and what you want to do with the water. If you live somewhere that charges for water use, you might be better off saving the water for use in your garden or something like that.

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