Most people tend to think that having a damp crawl space is normal. After all, the craw space is a below-grade space underneath your building and in direct contact with the ground. As the ground wet and dry through different seasons, it is a norm to expect the condition within your craw space to change. While this is true, taking the effort to maintain a dry crawl space is always recommended for a wide range of reasons. Generally, if you have a foundation with a crawl space, you want to keep the humidity level at 55% or less. This is important to avoid undesirable effects of damp crawl spaces such as poor air quality, mold growth, dust mites, and damage to the building itself. This article i going to teach you how to stay protected from moisture in crawl space by highlighting areas of concern and remedy.

Moisture In Crawl Space:  Causes, Problems, How To Fix & Protected

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What Causes Moisture In The Crawlspace?

To begin with, the first step to fix a damp crawl space is to find out the cause of the dampness in the first place. Generally, abnormally high moisture levels in crawl spaces can be attributed to water from the following sources:

  • Surface water: Water from a gutter, roof drainage, leaking windows, or grading issues
  • Groundwater: Water from the surrounding soil around the foundation
  • Plumbing issues: a burst or leaking pipe and other plumbing issues.

There following are some of the most common causes of moisture problems in crawlspaces

  • Improper Grading

During the construction phase of your building, if the ground is not properly graded, surface water may be trapped against the building foundation anytime there is torrential rain or flood. This will cause a moisture problem in your crawl spaces.

  • Cracks & Gaps in the Foundation

Foundation settling as a building begins to age can lead to cracks and gaps in the foundation. These may serve as conduits through which water seeps into your crawl space.

This can lead to water seeping into your crawl space. If water begins to seep into your crawl space, it all

  • Leaking Window Wells (vent wells)

Typically crawl spaces and basements tend to have vents and windows. This area is typically referred to as the window well. If there is a gap in this part of your crawlspace, water may seep into the space causing a moisture problem. To avoid this, it is always recommended to always keep an eye on this part of your crawlspace and have the vents and window wells repaired as soon as you notice a problem.

  • Problem with the waterproofing

An essential part of constructing a building is to waterproof it. This ensures that your home remains dry under various circumstances. However, damage or weakness in this waterproofing can allow moisture into your space.

  • Water and Sewer Line Malfunction

Asides from water from outside, excessive moisture levels in crawlspaces may also be attributed to water from within your home. Your home plumbing handles a tremendous quantity of water every day. Damage in any part of the system that brings in water and takes waste out of your house can cause a moisture problem in your crawl space.

  • Clogged or overwhelmed drains

A poor drainage system can also increase the probability of dampness in your crawl space. While drainage systems are installed specifically to prevent this, torrential rain may sometimes overwhelm such a system causing water to flood your home.

Problems of too Damp Crawlspace

Even before it becomes an obvious problem, excessively damp crawl space has some subtle adverse effects on your home. Excessive moisture levels in crawl spaces can potentially affect the building as well as its occupants in various ways. Some of the problems that may arise due to damp crawlspaces include:

1. Higher energy bills

You might probably not know this but your crawlspace is an integral part of your building’s cooling and heating system. Because damp air requires more energy to cool or heat, a damp crawlspace can potentially drive your HVAC energy costs high.

2. Mold Growth

Moldy growth is an expected consequence of high moisture level. The conditions in a damp crawl space present the perfect condition for mold growth on wood, paper, furniture, and other materials.  Not only does mold cause damage to your building and fixtures in it, but it also releases airborne spores which often cause respiratory problems.

3. Dust Mites & Pests

Most household pests thrive best in a damp environment. Hence, a dirty and humid crawl space serves as a perfect breeding ground for them. Microscopic parasites like dust mites release particles that float in the air triggering asthma and other respiratory allergies. Larger pests like spiders, termites, rats, and even snakes may find your humid crawlspace conducive for them as well.

4. Damage to your building

Wood tends to absorb water and expand or contract as the moisture level changes. This leads to a wide range of structural problems including warped or uneven floors, walls, and other wooden parts of your building. High moisture can also lead to rots and other forms of water damage.

How To Fix Moisture In Crawl Space

If your crawlspace is damp, you need to fix the moisture problem. The starting point of course would be to identify the underlying cause of the moisture problem. First, you need to schedule a quick inspection of your home. This will help discover the root cause of the problem and fix it. In most cases, it is a simple exercise that can be completed in less than an hour.

A crawl space inspection usually involves measuring the moisture level with a hygrometer. This will help determine if you have a moisture problem and how big of an issue it is. Afterward, the source of the problem is identified and subsequently fixed. For instance, if the cause of the dampness is a damaged plumbing fixture, any other measure is taken to fix the problem without first addressing the plumbing issue will be ineffective.

Some of the measures to fix a damp crawlspace include:

Installing a sump pump: a sump pump can be considered the first line of defense against moisture problems in crawlspaces. Installing a pump with a strong sump liner, impervious lid, and a battery backup system will help keep the water out.

Encapsulation: This involves installing a thick vapor barrier that will help lock the moisture out. You should also work on replacing damaged insulation fixtures

Fix plumbing issues: cracks, leaks, and other forms of damage in your plumbing should be fixed. Water pipes should also be insulated to avoid condensation

Good drainage: downspouts should be fixed. Gutters should also be cleaned regularly to ensure they effective channel water away from your foundation walls

Installing a dehumidifier: as the name implies, a dehumidifier is a device that removes excess humidity from a space. This can be in the form of whole-room/central dehumidifier or smaller more portable units. They have varying capacities depending on the size of the space you intend to dehumidify.   


In the US, up to 15% of all homes have a crawlspace. If you have a crawlspace in your home, then there is a high chance that you will need to deal with humidity issues at some point. A damp crawlspace can lead to water damage both to the building itself and to items in your home. That’s not to mention the associated health risk of living in a home with poor air quality. This is why you must pay attention to the moisture level of your crawl space and take steps to mitigate it as soon as a moisture problem is suspected.