Crawl Space Encapsulation

What is Crawl Space?

The narrow space between the ground and the first floor is called a crawl space. It is an unfurnished, rough, small space within any building. The crawl space, as its name indicates, is a small space with a crawling area only. The crawl space is approximately one to one and a half meters in dimension. It is such a narrow area that no person can stand straight within the place.

Why Do Homes and Buildings Have a Crawl Space?

The two prime reasons homes and buildings have crawl spaces are accessibility and cost. Since crawl spaces operate by ventilation process of letting outside air flows within the buildings and houses. The crawl space provides several benefits, including:


It is pretty expensive to leave the dust-sloping area made of concrete, while a crawl space neutralizes that requirement.

Accessibility and Convenience

Crawl space provides a convenient place to fix the piping and HVAC unit. It also distributes the sewer and water circulation throughout the house. The crawl space also makes future replacements and repairs easier.

What is Crawl Space Encapsulation?

The sealing technique that uses to line the crawl space walls and floor is called Crawl Space Encapsulation. The lining is composed of overlying layers of thick and dense polyethylene plastic.

The encapsulation produces an airtight vapor block that clasps moisture out of the crawl space floor area. Along with thick plastic lining, many people use to install a dehumidifier to constrain moisture levels. The crawl space encapsulation takes two or more days and makes the space perfect for the long run.

Why Use Crawl Space Encapsulation?

Unluckily, with transcendent cost-savings and availability comes high accountability and responsibility and the homes constructed over crawl spaces prone to moisture-related issues. The reason behind this is the crawl space’s surroundings. The principal problems often encountered due to poorly maintained crawl spaces are wood rot, molds, and termite infestations.

An excellent way to combat moisture issues is crawl space encapsulation. It will considerably lessen the amount of moisture and ultimately reduce the crawl space’s risk for:

  • Mildew/Molds
  • Structural damage and wood rot
  • Floor failure
  • Increased cooling and heating bills
  • Decreased insulation R-values
  • Insects
  • Odors
  • Allergy intensification
  • Dust mites
  • Poor indoor air quality

How does Crawl Space Encapsulation work?

Crawl space encapsulation builders follow approximately the same measures and steps while performing encapsulation methods at any building or home. These steps are:

  • An analytical evaluation gets done before encapsulation of the vented crawl space state.
  • Excluding old packing and insulation, fixing all moisture problems, exterminating pests, repairing cracks (if any).
  • An insulation spray foam material will imply to seal vents, holes, spaces, and gaps throughout outer ducts and pipes.
  • A heavy-duty poly plastic vapor barrier will employ on the walls and floor of the crawl space.
  • Restraining parts and keeping them together with fasteners or tape to guarantee there are no holes left.
  • A dehumidifier gets installed that keeps the moisture levels low 50% around the year.

Types of Crawl Space Encapsulation

Poly Plastic Based Crawl Space Encapsulation

As the name suggests, the encapsulation uses thick and compressed sheets of poly plastic. The poly plastic sheets cover the foundation walls, floors, and roof of the crawl space. It is a heavy-duty, white polyethylene vapor barrier for the crawl space that blocks moisture.

After the full packing of the crawl space area, another step is to install a dehumidifier. It controls the moisture levels of the space below 50% around the year. Dehumidifier also supports cleaner air and excellent storage for many items. Hence, producing an efficient solution to various problems.

Cement Based Crawl Space Encapsulation

The cement-based crawl space encapsulation consists of a three to four-inch layer of non-structural cement. On the top of the vapor barrier, this concrete layer gets poured. The method stops rodents and rats infestation in the crawl space and basement, and that is why called a mud slab or rat slab. The procedure improves the passage of clean air and provides an excellent storage place. The concrete insulation is perfect for crawl spaces where poly plastic packing does not work.

Which Type of Encapsulation is better, Plastic-based or Concrete?

When it comes to the type of crawl space encapsulation, concrete is the winner. Cement-based encapsulation has several benefits over the conventional plastic-based procedure. Here are some reasons why concrete is better:

Rats and Rodents Extermination

It is a common problem that rodents and rats chew and destroy poly plastic materials. And because of this damage, the life of the poly plastic crawl space encapsulation is lesser than concrete insulation.

Rat and rodent extermination is no doubt a great challenge that too with powerful pest control stratagems. It is a daily issue we have come across that rats ruin and chewed the plastic sealing. However, rodents have vanished the second after rat slab or mud slab installation.

Wall Moisture

It is a common phenomenon that the poly plastic crawl space approach allows the water and moisture to pass within the crawl space support walls letting molds and fungi develop behind the plastic material. However, concrete-based crawl space encapsulation is tight and fully packed and does not promote any moisture-related issues.

Irregular Poly Plastic Encapsulation

In poly plastic crawl space encapsulation, there is a chance that plastic will not set perfectly, and the incorrect material setting will allow moisture to seep into the plastic and break the idea of crawl space sealing. However, the concrete crawl space encapsulation approach is sturdy in every way and does not allow any seep into the crawl space walls and floor.

The cement-based method has various other benefits that include:


The poly plastic-based method needs regular checkups because plastic sealing gets easily destroyed by rats/pets or moisture. Cement gives powerful safeguard and protection on these factors.

Environment Friendly

The mud slab or rat slab is an environment-friendly method. The procedure does not involve plastic at all that is degrading for the environment.

Sufficient Storage Area and Easy Access

The crawl space has all the wirings, home plumbing, and HVAC ductwork. Thus, the rat slab encapsulation will provide easy access for repairs and maintenance. Cement crawl space encapsulation evens the space and provides a proper storage place also.

Final Thoughts

The crawl space encapsulation is the best way to keep the space dry and clean. Other than that, there are several other advantages of encapsulation. Such as the crawl space encapsulation keeps the home free from molds and fungi.

Like insects and pests, mold grows in moist walls and floors. An unsealed and opened crawl space is the most vulnerable place. We all know that mold is a health risk. Susceptibility to mold spores can trigger respiratory issues and allergies. Crawl space encapsulation guarantees your crawl space endures dryness, rejecting mold the chance to grow and infest your living space.

Another advantage of crawl space encapsulation is its cost-efficiency. Since sealed crawl spaces have conditioning and insulation, the crawl spaces are more cost-efficient and energy-efficient. The insulation improves energy-saving, and managing the HVAC becomes far minimum than non-sealed and non-encapsulated crawl space.

Encapsulation of the crawl space increases the comfort levels of any house or building. A non-vented or opened crawl space makes the place warmer in summer and colder in winter. Both situations can make the indoors unendurable. Any external changes will result in a difference in the interior conditions too. It is significant to know that fifty percent of the indoor air comes from the crawl space. By encapsulating or sealing this space, one can prevent toxic gases from leaking into our homes.

It is also a fact that dark and moist crawl space always an attractive place for crawling insects, mods, and pests. Once pest infestation starts, they reproduce quickly and spread all over the house. This situation is damaging for interiors, wood joists, and other items. The most worrying part is the pests and insect extermination because the process is tedious but costly also. A well-designed crawl space encapsulation be it a concrete one or polyethylene vapor barrier it will block the entry points of the pests and insects, also inhibit the growth of molds and fungi.

When the crawl space foundation does not seal properly, there is a high risk of weakening the foundation. Because water constantly flows from the crawl space foundation walls and makes its way to the floor. The whole situation is damaging for the building’s structural integrity.

A well-encapsulated crawl space will provide safety from all these hazards. When the sump pump system and interior drainage couple with the crawl space sealing keep the soil around the house foundation dry, soil shifts and stops cracks that cause grave damage to the house or building structure.

We all know prevention is better than cure and a well-encapsulated crawl space extends several lasting advantages. That includes a healthier, clean, and comfortable house. So, if you have a crawl space outside your building, examine it, if it needs encapsulation, and if yes, do it in the first place.


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