Find the Source of Water in a Crawl Space and Remove It

Crawl space under a house
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Water in your home's crawl space is more than just irritating. It can eventually create so much mold that major repairs are necessary. At the extreme end, structural members are weakened and the home will need the attention of a general contractor. The logical first step is to identify the sources and then mitigate the water.

Assess If Water Is Coming From Below Grade 

Imagine that you live in a very wet area. Under your house, in the crawl space or unfinished basement, is a permanently wet area. After a hard rain, the wet area's diameter expands from inches to several feet. The ground, instead of merely being muddy and spongy, begins to pool up with water. During the dry months of June to October, the pool of water shrinks, but it never completely goes away.

If this type of moisture problem sounds familiar, the water is coming up from the ground. Though seasons can affect it, it mostly transcends seasons. 

If Water Is From Above Grade, It May Be a Plumbing Issue

The water might be attributed to a leaking water supply or drain pipes. If a water-related action happens within the house and more water develops in the crawl space, that is your likely culprit. Water-related actions might be when someone takes a shower; when the dishwasher runs; when a toilet flushes; or when a bathtub drains.

Water Plus Lack of Light Creates Mold

With excessive water in the crawl space, you have the related problem of mold. Mold loves to grow in places that have moisture and lack of light. Both conditions perfectly describe a crawl space.  

Mold will grow on the piers, joists, ducts, and other hard surfaces. But mold also grows on soft materials, such as fiberglass insulation and on the plastic vapor barrier. These surfaces are difficult to repair because the mold cannot be cleaned off. The only solution is to remove the material and replace it.

Who Should You Contact?

In water-prone areas, certain companies specialize in water mitigation services. Do not confuse them with basement drying and restoration companies, which come in after the problem has been fixed. Restoration companies clean and dry out the areas, but they do not fix the problem. Search for companies that advertise for basement or crawl space waterproofing and drainage repairs. General contractors also can do this work for you.  

How Water Mitigation Companies Fix the Problem

The general process for controlling water in a crawl space involves setting up a perimeter within the crawl space and capturing any water that tries to infiltrate that perimeter. When water hits this border, it is diverted into gravel-filled channels and fed by gravity to a sump pump. The sump pump then syphons up the water and purges it from the crawl space.

  1. Protect: Unless you can access your crawl space from the exterior, you will need to bring in materials through the house and down an access door. You will need to protect all walk areas with plastic. To prevent slipping, you can use kraft contractor's paper, an inexpensive item available at all home centers.
  2. Remove the Vapor Barrier: Your crawl space may already have a plastic vapor barrier. Remove this and tightly roll it up for easier transport through the access door.
  3. Dig the Trench: Dig a trench around the entire interior foundation, using the foundation as a guide. The trench should be between 8 inches and 24 inches from the foundation. If the trench is any closer to the foundation, it undermines the foundation and the home itself.
  4. Lay Drain Pipe: Lay down 3-inch socked flex perforated pipe through entire perimeter trench.
  5. Cover with Gravel: Cover the pipe with drain rock.
  6. Spread the Soil: What should you do with all of that remaining soil? While you can remove it, it is often easier to spread it evenly around crawl space.
  1. Install a GFCI: Install a GFCI outlet in the crawl space. The company will contract an electrician to do this.
  2. Install a Sump Pump: At the low end of the perimeter trench, install a sump pump as recommended by the manufacturer's directions.
  3. Discharge to the Exterior: Make sure that the sump pump discharges the perimeter trench water to the outside.
  4. Install the Vapor Barrier: Install a new 6 mil vapor barrier to prevent vapor transfer to the crawl space.

Fix the Crawl Space Yourself or Hire a Company?

Water mitigation is not difficult to understand but it is certainly hard back-breaking physical labor. You may opt to hire a contractor. Consider these factors before taking on the project by yourself:

  • Power: A GFCI outlet must be installed in the crawl space for the sump pump. Mitigation companies will not do this. It must already be in place or you must contract out an electrician to install it. Optionally, you may be able to do your own electrical repairs.
  • Low Ceiling: A crawl space that is between 4 feet and 5 feet high is considered tall. Even such a tall crawlspace is very difficult to move around in. Many crawl spaces are lower than this height.
  • Heavy Materials: Hundreds of pounds of bagged drain rock must be carried into the crawl space, along with hundreds of feet of perforated pipe.
  • Tight Access Point: There may be only one small door that allows access to the crawl space, and this door may be located in some inconvenient place, like a bedroom closet or kitchen pantry.

How Urgent Is It?

For anything dealing with water, low light, and enclosed spaces, the best answer is usually that you should do this immediately. But how immediate is immediate?

Water can sit in the crawl space for months or even years without having any overt adverse effect on your house. This may give you the deceptive impression that everything will be fine for the length of your ownership of the house. However, over the long term, you are in for trouble: standing water can damage the house's foundation; wooden beams and joists will begin to rot; various strains of mold can develop. Even if you are fine with standing water in your crawl space, you will be required to fix the problem when it comes time to sell the house.