Crawl Space Encapsulation – Complete Guide

What Is A Crawl Space Encapsulation?

Crawl space encapsulation means completely sealing your crawl space (home or commercial property) to avoid moisture and mold issues. Crawl space contractors suggest crawl space encapsulation to eliminate crawl space problems like moist, filthy, moldy, and flooded into a fresh, sterile space.

The sealing solution includes lining the crawl space base walls and also a ground using thick rubberized vinyl sheets or concrete to solve multiple crawl spaces problems.

Different Types Of Crawl Space Encapsulation

Plastic Based Crawl Space Encapsulation
Crawl Space Encapsulation

The floors, foundation walls, and the ceiling of your crawl space are sealed with a white, heavy-duty polyethylene crawl space vapor barrier.

Space is completely sealed and then a dehumidifier is installed to regulate the crawl spaces moisture, to promote cleaner air and great storage for many things thereby providing an effective solution to multiple problems.

Concrete Based Crawl Space Encapsulation (“Rat Slab“)

In the case of the concrete-based approach, a layer (3-4″) of non-structural concrete is poured on the top of black vapor barrier which is placed over the crawl spaces ground. THis procedure is also called a rat slab or a mud slab.

As the name suggests, it prevents rats and rodent infestation in the basement area /house or building as well as promotes the clean air and storage place for the house.

This is the perfect solution for multiple crawl space problems in regular situations as well as instances where the plastic-based approach fails.

Top Benefits Of Crawl Space Encapsulation In Home

crawl space encapsulation benefits info graphics
  1. Clean Crawl Space – As you cover the crawl space with plastic or concrete, it keeps the crawl space and overall foundation area clean. No more expensive crawl space cleaning
  2. Prevent Mold & Fungus– If you have excessive moisture issues level in the crawl space then it allows mold and fungal growth in the wood, floor joists, or floors. Moisture problems are harmful to the crawl space as well as the property. Crawl Space Encapsulation controls the moisture level (using dehumidifier) and thereby prevents mold and fungus growth.
  3. Improve Indoor Air Quality – Due to clean crawl space, under control moisture problems, and the prevention of mold and fungus growth, it improves the overall air quality in the house. Your indoor air quality will improve and will be maintained the same over time.
  4. Stop crawl space flooding – Plastic or concrete-based encapsulation will put in place a strong drainage system along with a sump pump to handle the flood issues in the crawl space. It thereby controls the moisture or water-related damage. The sump pump makes sure that any water is pumped out of the crawl space and maintains the crawl spaces dry.
  5. Reduced Utility Bills – Once you do proper crawl space encapsulation, there are fewer chances for energy loss. Crawl Space Encapsulation (plastic or concrete) aids in energy efficiency and thereby saving homeowners hundreds of dollars in energy bills to heat the crawl space or cooling costs.  
  6. Cozy Environment During winter– Crawl Spaces are sealed and insulated and it results in increasing energy efficiency by keeping the air warm in your home.
  7. Appreciation in Home Value – Your investment in crawl space encapsulation makes sure that home value increases in proportion to homeowners’ investments. It gives confidence to the home buyers that the overall living conditions in-home and crawl space are great due to the protective measures. No more worries about weak foundation walls.
  8. Protects The Wood – Mold growth (as a result of moisture) in the crawl space endangers the wood in your crawl space. It can also create problems for crawl space foundation. Crawl Space encapsulation controls the moisture level and thereby controls or stops mold growth. This helps in eliminating the wood rot in your crawl space. Once you eliminate the wood rot then you don’t need to worry about mold spores and related remediation measures!
  9. Pests Infestation – Excess Moisture creates a suitable environment for pests, rats, and vermins to inhabit the crawl space. Homeowners dread the pest infestation. Crawl space encapsulation secures the crawl space, eliminates excess moisture, and prevents the pest infestation
  10. Less Ongoing Maintatence – Typical encapsulation project will need a one-time cost from the homeowner. However ongoing charges to maintain are minimal.
  11. Reduced Radon Exposure – Crawl Space encapsulation creates the barrier for radon gas to pass through crawl space into the home. It remediates the radon exposure to a certain extent.
  12. Secured Crawl Space – Imagine the relief to the homeowner, when you know that you have secured the crawl space with encapsulation material (plastic or concrete) to prevent dirt, radon, mold, water, and pest from hurting your crawl space foundation and thereby home

Step By Step Guide To CrawlSpace Encapsulation In Home

Preparation – This Is Relatively Common Across Both Ways


  1. Carry out a thorough inspection of your crawl space floor area & foundation in-homes or commercial property.
  2. If it is an uneven floor then some groundwork will be required to level the ground. Also, look out for any pest issues or rat problems.
  3. Then the ground area is properly cleaned (remove any dead rats, feces, or other debris), sanitized with materials, and deodorized to remove any foul odor. If there is a pest infestation then pest control treatment is carried out.

Drainage System

crawl space waterproofing

In this step, the floor is graded and if required installed with a drainage system with an appropriate discharge using a mechanical system (sump pump) or leveraging a gravity system to ensure that water is properly removed from the crawl space using a sump pump – if needed.

The sump pump installation is the major step of concrete encapsulation or rat slab (depending on the situation) to achieve crawl space waterproofing. Sump pumps keep your crawlspaces dry. It is installed beneath the crawl space floors where water often collects.

Crawl Space Encapsulation Plastic Specific Step

Polyethylene Barrier (Vapor Barrier)

  1. In this phase, we will cover the walls using plastic (kind of Cross-laminated High-Density Polyethylene). Make sure to attach it with strong adhesives.
  2. In the next phase, the ground is covered by the plastic vapor barrier (white, black or yellow). Please note that the density of the plastic going on the ground is thicker than the one put on walls.
  3. Measure and properly cut the material before installing. Cut larger than you need and overlap them when installing to cover every gap.
crawl space vapor barrier

Crawl Space Encapsulation – Concrete (“RatSlab”) Specific Step

Concrete-based crawl space encapsulation is the relatively straightforward but most comprehensive and highly recommended process to encapsulate your crawl space.

Vapor Barrier

Installing a crawl space vapor barrier is the third major step of the rat slab, to prevent moisture. They are installed along in or around walls, ceilings, and floors to prevent moisture from spreading and potentially causing water damage.

It creates good drainage around your home to prevent rainwater from flowing in under your house and keeps the concrete floor sloping. It is the best way to keep the moisture away by covering the dirt floor with a plastic polyethylene vapor barrier. Make sure to overlap any seams and tape them.


A concrete slab is the final step of a rat slab. Place the concrete slab (3-4″) directly on top of the vapor barrier, with a subbase of soil, sand, and gravel below. There are additives available for an additional cost which waterproofs the concrete as well.

The mix of soil or gravel or sand is especially important. If it is done improperly then it can result in cracks, raised areas, or low spots in the concrete. Also, a plastic layer which is the vapor barrier deters moisture from affecting the concrete floor in the future.

Iron rods can be fitted to prevent shrinkage, cracks from spreading throughout. Pipes and wires can also be installed before pouring the concrete.

crawl space foundation repair

Post Encapsulation Steps


Dehumidifier plays a key role in maintaining the suitable temperature in the crawl space. Dehumidifiers eliminate the moisture from the crawl space air. Depending on the crawl space situation, the contractor will recommend installing the dehumidifier. It’s important to keep humidity levels below 50%. It will be achieved through the dehumidifier.

crawl space dehumidifier

Insulation (Common Across Both)

Insulation enables the requisite temperature in your crawl. It will basically shield you against the cold during the winter and heat during the summer. Insulation is the key driver to make your house energy efficient. Whether you opt for a plastic vapor barrier-based approach or a concrete-based approach, insulation is highly recommended.

There are various types of insulation mechanisms like spray foam insulation, loose-fill insulation, batt insulation, or foam board insulation. It’s highly advised to consult a professional insulation contractor to decide on the suitable type of insulation and install it in a professional manner.

2022 Crawl Space Encapsulation Cost Guide

If you are wondering how much it would cost you to encapsulate your crawl space (home or commercial property) in 2022 then you are in the right place.

There are various factors to consider and it can increase or decrease the price accordingly – size and condition of your crawl space, type of insulation, the thickness of the vapor barrier, sump pumps, and dehumidifiers. 

Here are the various components of crawl space encapsulation cost

  1. Crawl space inspection (Note: RatSlab offers free inspection)
  2. Crawl space cleaning
  3. Crawl space drainage/water removal
  4. Foundation Repair – if needed
  5. Vapor barrier installation
  6. Sealing vents and holes
  7. Dehumidifiers
  8. Concrete (for concrete based approach)

Crawl Space Encapsulation – Plastic

We do not recommend strictly plastic based crawl space encapsulation.

Crawl Space Encapsulation – Concrete (RatSlab)

RatSlab installation cost vary depending on cleaning, grading, water drainage/waterproofing, insulation, and pouring the concrete.


Conclusion: Plastic Based Encapsulation Or Concrete Based Encapsulation

Winner: Concrete Based Crawl Space Encapsulation = Rat Slab

Concrete-based encapsulation has a number of advantages over the traditional plastic-based approach. We highly recommend a concrete based approach due to following reasons:

  1. Rats Extermination – It is a common scenario that Rats chew plastic material and also damage insulation. Rat Extermination is a big challenge even with strong pest control measures. Every day we come across scenarios where plastic has been chewed and thereby defeating the whole purpose of sealing the crawl space. However, Rats have literally disappeared the moment we installed the Rat Slab.
  2. Moisture on the wall – A plastic-based approach allows the water to flow through the crawl space foundation walls causing mold to grow behind the material.
  3. Improper Plastic Encapsulation: If incorrect material or approach has been used then it is very much possible that moisture will seep through the plastic and defeat the purpose of crawl space sealing. The concrete-based approach has a big advantage in this scenario.
  4. Maintenance: Plastic based approach requires regular checkups to make sure it has not been damaged by pests/rats or due to other reasons. Concrete provides strong protection against these factors.
  5. Eco -Friendly – Rat Slab is the eco-friendly approach due to the overall approach as well as materials being used.
  6. Easy Access and Storage Area: The home’s plumbing, wiring, and HVAC ductwork occupy the crawlspace. Thus, the concrete slab crawlspace will allow easy access for maintenance and repairs. Concrete crawlspace even becomes a suitable place for storage too.

Now that you have a solid understanding of crawl space encapsulation, please feel free to emails us at contact@ratslab.com or call us on +1-855-RAT-SLAB to discuss further.