Selecting Crawl Space Dehumidifier for Your Home

Posted by AlorAir Alex on

You cannot control the amount of humidity outside your home but if this moisture is able to find its way into your crawl space, there will be numerous problems.

Excess humidity in the crawl space causes:

  • The growth of mildew and mold – moist surfaces of the crawl space are the perfect place for mold and mildew to grow.
  • Dampness and odor in the crawl space - Most crawl spaces lack enough ventilation to allow good circulation of air, the air smells damp. If this air is not cleaned it could spread the odor into the house.
  • Structural damage – excess humidity in the crawl space affects the structural integrity of the crawl space’s walls and floor causing cracks. This can greatly decrease the value of your house.

The crawl space dehumidifier is the homeowner’s easiest and most effective option to deal with humidity in the crawl space. A crawl space dehumidifier is specially designed to operate optimally even at low temperatures in crawl space.

Do you need a crawl space dehumidifier?

To determine whether you need a crawl space dehumidifier, you can:

  1. Buy a hygrometer to measure the exact level of humidity in the crawl space. A hygrometer can be easily found at many retail outlets.
  2. If you cannot access a hygrometer, you can carry out a simple inspection of your crawl space.

The levels of humidity can be classified into:

  • Moderately damp – Feels damp and smells musty during the humid weather months.
  • Very damp – the crawl space feels damp and smells musty all year round.
  • Wet – visible water stains on the walls and floor of the crawl space.
  • Extremely wet – standing water can be seen all over the crawl space floor.

Note: it is important to determine the leading cause of humidity in the crawl space. Leaking water pipes and lack of proper drainage are some of the major causes of increased humidity. Fixing these problems can greatly lower the level of humidity in the crawl space.

How to select a crawl space dehumidifier for your home?

Today there are so many brands of crawl space dehumidifiers in the market it can feel overwhelming for many homeowners to choose the right one.  Once you have determined the level of humidity in the crawl space you need to measure the size of the crawl space (in cubic feet).

With this information, you can easily determine the capacity and airflow requirement the crawlspace dehumidifier should have.

1, The airflow of a crawl space dehumidifier - This refers to the cubic feet of air the dehumidifier is dehumidified per minute.  The air change per hour (ACH) refers to the number of times the air is cycled through the dehumidifier per hour. Crawl space with high humidity will require a dehumidifier with a higher ACH.

    Humidity levels

    Recommended ACH.

    Moderately damp (60 – 70%)


    Very damp (70 – 80%)


    Wet (80 – 90%)


    Extremely wet (90 – 100%)



    Check the Dehumidifiers ACH before you buy it.

    2. The capacity of crawl space dehumidifier – the capacity of the crawl space dehumidifier is the number of pints of water it extracts from the crawl space. The right capacity of the dehumidifier is dependent on the level of humidity in the crawl space. Higher levels of humidity dictate you buy a crawl space dehumidifier with a higher capacity.

    What other features should you consider?

    • The crawl space dehumidifier must be energy efficient (energy star rated).
    • Auto humidistat – the dehumidifier should be able to turn on and off depending on the humidity levels in the crawl space. This saves a lot of energy.
    • Self-draining dehumidifier – saves time and is convenient for the owner, because you don’t have to keep emptying the collection tray.
    • Air filtration – buy a crawl space dehumidifier that is able to clean the odor and remove the mold spores in the crawl space.

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