Not All Crawl Space Encapsulations Are Created Equally Part II - Water Infiltration, Vapor Barriers, and Insulation

Tuesday, July 3rd, 2018 by Erin Dougherty

Water Infiltration

Standing Water in Crawl Space

Water infiltration can be a major problem for many homeowners. Some crawlspaces are subgrade, while others are above grade this makes a difference in how we address drainage solutions and how water enters the crawl space. Some homes have water that pools around the foundation or rises up from the ground and into the crawl space – this usually happens with a high water table. Sub-grade crawl spaces typically have less dense soil around the foundation that hold water. This can expand and apply pressure against the foundation walls, resulting in cracks. Water can seep in through these cracks and be absorbed and wicked through porous cinderblock walls and into the crawl space. Resolving water infiltration requires Interior foundation drainage.

Sump Pump and Interior Foundation Drainage

  • Interior Foundation Drainage – this is exactly what it sounds like, drain lines are installed inside the crawl space and direct water to a sump pump, usually installed in the lowest area of the crawl space. From here water is pumped out of the crawl space and away from the home.

Choosing a drainage solution may be limited based on the specific issue your home has. Understanding how water is entering your crawl space is the first step to determining what solution is best for you home. Not all homes need a drainage solution. This is why it is important to have a professional assess your home’s crawl space. Many homes are affected by a buildup of moisture from high relative humidity and not water infiltration. If water infiltration is an issue, regardless of source, it must be managed, regardless of whether or not the crawl space is going to be sealed. In the case of the sealed crawl space, the liner joinery is not designed to “sit” in a ponding crawl space as the bulk water will eventually breach the seams of the liner. 

Vapor Barriers

Attaching vapor barrier to crawl space wallsVapor barriers come in various thicknesses and brands.  There are several options for your vapor barrier based on how you plan to use your crawl space. Thicker vapor barriers allow you to have servicemen work in your crawl space without worrying about tears or rips in the liner. Higher quality vapor barriers may include an antimicrobial that helps prevent mold and mildew from breaching the vapor barrier and allows you to use your crawl space for storage as well. Determining the best vapor barrier for your home depends on what you plan to use your crawl space for and how durable you want the space to be. You will also want to consider any warranties that each option offers, as they can make a big difference in the liner you decide to choose.


Insulating your crawl space helps control temperature and extends the thermal barrier of your home, to grade. Insulation is measured in R-values. R-value is the ability of any material to resist heat flow. The higher this value is, the better insulator it is. Insulating in the crawl space offers three options. Fiberglass batts, rigid foam board insulation, and spray foam insulation. Chances are, your current crawl space is insulated from your home’s floor joists with pink or brown fiberglass batts. It is likely that this insulation is falling, saturated, or the paper backing, an organic material, is the host for mold to grow. Fiberglass insulation, when saturated can give off an odor similar to ammonia or cat urine. Since fiberglass insulation can absorb and hold water, if it is still in the joists, it can hold moisture against the floor joists saturating them and promoting mold growth. This eats away at the integrity of the joists in your crawl space and can cause serious structural damage.

  • Rigid Foam Board on Crawl Space WallsRigid Foam Board – thick sheets of foam insulation with a reflective backing on one or both sides (the brand we use, Foamax, is white on one side and silver on the other). This insulation comes in a 1.5-inch thickness offering an R-10 value. Rigid foam insulation does not absorb moisture, and since it is not a product made with organic materials, it does not promote mold growth.
  • Installing Closed Cell Spray Foam Insulation on Crawl Space WallsClosed Cell Spray Foam Insulation – at 1.5 inches can act as an air barrier. This means that it is not only keeping air from entering the crawl space. Spray foam insulation can be applied in varying thicknesses and offers a superior R-value per inch over other insulation materials. 

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The Drying Co./ThermalTec
236 Industrial Blvd
Suite A
Toano, VA 23168

The Drying Co./ThermalTec
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P.O. Box 637
Toano, VA 23168
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