Crawl Space Waterproofing
Homeowners in Charlotte, Hickory, Lake Norman, Winston-Salem, or surrounding towns can trust Dry Otter Waterproofing for expert crawl space waterproofing, and honest advice about it.
No foundation type is perfect, and crawlspaces, in particular, have their own set of challenges. Unlike other foundation types, crawlspaces have dirt floors and vents that allow moisture in. According to the U.S. Department of Energy, excessive moisture in crawl spaces can contribute to structural damage and indoor air quality concerns. Also, water seeps right under the foundation walls.
In the days when home footprints were smaller and more simple, and crawl spaces were fully ventilated, moisture buildup was not a problem. This thought concept has been carried over in modern times but the conditions are not the same. The U.S. Environmental Protection Agency (EPA) notes that such spaces are susceptible to moisture problems and mold growth, which can adversely affect health and home integrity. As a result, crawlspace waterproofing has become necessary to overcome these challenges.
What is a crawl space?
A crawl space is an unfinished space beneath a building for accessing plumbing, wiring, or HVAC systems. They are usually shallow; only tall enough to crawl in. Crawl spaces usually have dirt floors, but sometimes have portions of concrete floor. Out of the three main types of foundations, crawl spaces are the most prevalent in North and South Carolina.
Pros
- access to a home's utilities
- easier to remodel home
Cons
- pipes may freeze
- may require waterproofing
- home may require stairs
Parts of a Crawl Space
Crawl Space Waterproofing Terminology
- downspout- a vertical pipe that carries rainwater from the roof’s gutter system down to the ground.
- insulation- material installed under the floor or between the joists that reduces heat loss
- floor joist- horizontal piece of wood that supports the flooring above
- girder- a large beam that runs perpendicular to the joists, supporting their load; rests on pier or foundation wall
- footer (footing)- a wide concrete base that sits beneath the foundation wall
- pier footing- the base under each pier, made of poured concrete, that spreads out the load over a large area of soil
- pier- a vertical block column inside the crawl space that supports the girder
- backfill- soil that's placed back around the foundation after the home is built
- undisturbed soil- soil that was never excavated during construction
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Crawl Space Waterproofing Defends Two States of Matter
Water
Crawl spaces often get wet due to saturated backfill soil and hydrostatic pressure pushing moisture through foundation walls or up from the ground.
When rainwater or groundwater accumulates in the looser soil (backfill) around a home’s foundation, it can’t drain as easily as the undisturbed soil nearby. As this soil becomes oversaturated, it exerts hydrostatic pressure on the crawl space walls and floor. Over time, this pressure can force water through small cracks, porous concrete, or even under the seams of the foundation.
Add that to open vents, cracks around the door, and plumbing leaks, and your crawl space becomes a trap for water, with little chance for it to ever leave.
Vapor
Crawl spaces become damp due to a combination of exposed soil, unsealed vents, and the stack effect.
- Exposed soil releases moisture into the air
- Vents allow warm, humid outdoor air to enter
- The stack effect* keeps it going
The stack effect is the natural upward movement of air inside a home, where warm air rises and escapes through the attic, pulling air from the crawl space into the living areas. This means moisture in the crawl space can be drawn up into the home.
This humidity can lead to mold, mildew, wood rot, and insulation failure.
Signs You Need Crawl Space Waterproofing
Crawl space waterproofing prevents moldy air coming up from your crawl space into the living space. Mold poses significant threats to both health and home integrity. The Centers for Disease Control and Prevention (CDC) highlights that exposure to mold can lead to respiratory issues, especially in individuals with pre-existing conditions.”
Signs of a Wet Crawl Space Inside the Home
- musty smell
- mildew on baseboards
- breathing problems
- sagging floors
- cupped hardwood floors
- drywall cracks
- doors that stick
- windows that stick
- high energy bill
- increased pests
Signs of a Wet Crawl Space Under the Home
- fungal mold growth
- high humidity
- wood rot
- foundation wall cracks
- rust and corrosion on utility lines
- efflorescence
- increased amount of pests
- musty smell
- sagging insulation
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Crawl Space Waterproofing Solutions
There are a few different options on waterproofing a crawl space. Every building is different and every homeowner situation is different. Soil type, slope, and height of crawl space can dictate the best solution, as well as the homeowner’s finances and interest in building equity into the property.
Option 1
Eliminate Standing Water
Not every foundation requires a drainage system. Some homes have the proper slope and soil conditions that water naturally drains away. For those that are not that lucky, a French drain is necessary. A French drain is a ditch filled with gravel just inside the interior perimeter of the crawl space that allows the water to fill and drain to the lowest point due to gravity. Some homes are sloped just right so that the French drain can allow the water to flow out naturally with a gravity exit. Other homes require the French drain to route to a sump pump that uses electricity to pump the water up and out of the crawl space and take it many feet from the house.
Option 2A
Reduce Moisture with a Vapor Barrier
Even a property with excellent natural drainage, that does not require a French drain, will need a vapor barrier. Building code requires it. A vapor barrier, sometimes called a moisture barrier, is a sheet of plastic laid down on the floor of the crawl space. The EPA even suggests a vapor barrier in a crawl space to reduce moisture in the home. A vapor barrier is not taped at the seams. The sides are usually pinned down with stakes. Vapor barrier solutions go in crawl spaces with open or adjustable vents. Vapor barriers are usually black, white, or clear.
Option 2B
Almost Fully Eliminate Moisture with an Encapsulation
While vapor barriers are the more economical solution, crawl space encapsulations are the more effective solution. They are a permanent solution. While the purpose of an encapsulation is to “seal” the crawl space against moisture, a perfect seal is not possible, and some outside air will always get in, and that is why a dehumidifier must be installed. A dehumidifier is a mechanical device that processes the air to reduce the relative humidity by cooling it, collecting the condensation that creates, then warming the air back up before releasing the drier air back into the crawl space. Read HowStuffWorks: dehumidifiers here. Like all mechanical devices, needs to be maintained with annual filter changes. Manufacturers usually warranty the life of the dehumidifier for five years, and it’s likely they operate even longer than that when paired with a proper encapsulation and maintained properly. The liquid condensation can be directed to the sump pump, or when one is not in place, a small “condensate” pump.
Not and Option
A Hybrid System
A “hybrid” or “starter” ‘encapsulation’ system includes any type of moisture barrier on the bottom of the crawl space but not on the walls or piers, and includes a dehumidifier. The vents are sealed with makeshift covers to attempt to seal them, but overall there is not enough to protect the crawl space from moisture. Ultimately the dehumidifier will be overworked and will most likely have a short lifespan.
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Crawl Space Waterproofing Products
Crawl Space Encapsulation
Seal with plastic on the floor, walls, and columns. Paired with a dehumidifier.
Crawl Space Drainage
Some crawl spaces need French drains under the plastic moisture barrier.
Crawl Space Vapor Barrier
Plastic on the floor of the crawl space to block moisture.
Crawl Space Dehumidifier
Crawl space encapsulations need to be paired with a dehumidifier.
Sump Pumps
Sump pumps pump the water allowed to drain via a French drain.
Crawl Space Mold Remediation
Bleach won't work-- but the right cleaning solution can reduce the mold growth.
Crawl Space Insulation
Mold or moisture in a crawl space can mean insulation needs to be replaced.
Crawl Space Wood Repair
Wood rot can cause the support beams, floor joists, and subfloor to need replacement.
New Crawl Space Door
New crawl space doors help keep water and moisture out.
Crawl Space Waterproofing Case Study
- Chris M.
- Crawl Space Waterproofing
- Crawl Space Encapsulation
- Davidson, NC
During the sale of Chris’s home, the general inspection report revealed high humidity despite having a portable dehumidifier. He could also smell a musty odor on the first floor. Our inspector also identified ground water intrusion.
Our crew installed a pipe and gravel drain system, sump pump, and a 20 mil encapsulation system.
Now the relative humidity should stay below 65%, which will help keep that musty smell away, since mold can’t grow in an environment below 70% relative humidity.
Customer Review
“I purchased a home in March 2023.. the first house I’ve owned that had a crawlspace. House had a musty/ earthy smell on the first floor, and I knew it had high moisture levels based on the inspection report. Marcus came out for the initial inspection and quote. He was very thorough in explaining my options and was not bothered by my follow-up texts and calls after I reviewed my options.
Ultimately, I got the full encapsulation, French drain, and dehumidifier. I wanted to solve this problem and not have to worry about it again anytime soon. The crew that came out, William, Wesley, and Luis, were great. Special thanks to William who really takes pride in his work and made sure to send me pics of the progress. My house now has no smell on the first floor, and humidity in the crawl space shows 48-50% humidity which is the perfect amount for the crawlspace. Dry Otter does not cut corners and provides quality work. Thanks guys.”
More Case Studies
Benefits of Crawl Space Waterproofing
Moisture control and increased air quality are two of the most significant benefits that will add value to your home and make it a safe environment for everyone. Encapsulation can enhance a home’s energy efficiency by up to 15%, mitigate potential issues during real estate transactions, increase property value, and notably improve indoor air quality. The U.S. Environmental Protection Agency (EPA) underscores the importance of moisture control in maintaining healthy indoor air. The increased energy efficiency saves you money in the long run. Homes with a properly waterproofed crawl space retain your home’s value.
