Crawl Space Encapsulation: Pros and Cons


Crawl space encapsulation involves sealing the space with a polythene paper barrier for regulating moisture levels. The barrier can either be added when laying the foundation or even to an existing building. To learn more about this process, read through for more details as well as crawl space encapsulation pros and cons.

Is Encapsulation of Crawl Space Necessary

The questions that most new homeowners and builders ask cover such areas like the crawl space. Is encapsulation of crawl space necessary falls under the common questions one would ask if the space between the ground and their floor has mold. The answer is yes, especially if one needs to keep moisture out, prevent the risk of mold forming, and also to keep out pests and rodents from invading.

Why People Encapsulate Their Crawl Space

A homeowner may have their crawl spaces encapsulated to prevent:

  • Mold formation
  • Musty mildew smell inside the house.
  • Pest infestation in the house.
  • Escalated home heating and cooling costs.
  • Wet insulation
  • Windows appearing sweaty.

When to Encapsulate Your Crawl Space

Some of the common indicators that you may need to encapsulate your crawl space include:

  • High humidity in the living area.
  • Musty odors
  • Condensation on air conditioning equipment or ductwork.
  • Rot in wooden framing members
  • Insect infestations
  • Condensation on water or insulation pipes and truss plates in the crawl space.
  • Buckled hardwood floors.
  • Moisture or mold damage in the living area or crawl space.

The Basic Process of Crawl Space Encapsulation

The types and costs of materials may vary from one contractor to the other, but the basic process remains the same. The process may only be altered depending on the issues to cover and the size of the area the crawl space covers. The steps are as described below:

Preparing the Crawl Space

How you prepare the space determines the results as well as the crawl space encapsulation benefits. While starting the exercise, make sure to remove all the debris, including sharp rocks and anything else that may cause accidents or destroy your insulating material. Grading the ground follows to ensure the most level surface possible.

The Sealing Process

Vents, doors, and other external openings in the side walls should be sealed beforehand using plastic or foam. You should also ensure to seal all cables and pipes coming from the outside. The sealing is meant to block unwanted airflow while also helping to waterproof the crawl space. 


The insulation process involves laying a plastic material to the walls and floor. The plastic material going to the floor should be at least six millimeters thick and overlap by at least one foot. You should also ensure to staple it down and also make sure that it covers the entire area.

The thickness is recommended to ensure durability and enough coverage to endure termite inspections, plumbing, and other disturbances.

For the wall plastic insulation material, you can use metal fasteners and a nailer. There should be at least a 6-inch gap from the sill plate to allow for termite inspections. 


After the insulation and when the entire area has been sealed off, removing the existing moisture should follow. The moisture should be removed from the vents that lead to the dehumidifier unit and the living area. If the neighborhood is known to flood, ensure to add a sump pump and/or a flood alarm.

For the flood alarms, the Occupational Safety and Health Administration (OSHA) has the recommendations on their site.

Average Cost to Seal Crawl Space

Crawl space encapsulation costs cover the tools, labor, materials, and other installation factors. In general, the average cost to seal crawl space may range between $1,500 - $15,000 depending on how small or big the crawl space is. With the sealed crawl space pros and cons, as illustrated in this article, the cost may never stand between you and achieving your dream of dehumidifying your house.

The foundation wall insulation may cost between $0.5 - $2 per board foot. The average vapor barrier prices on their part will range between $0.5 - $0.75 while the seal vents may go for between $15 - $22 each. The drainage system would require between $600 - $1,800, the dehumidifier would ask for between $780 - $1,000, while there may be extra charges for cleaning and repairs.

The average cost to seal crawl space may, therefore, not be constant due to a range of reasons. Your professional damp proofer or home builder may then be the best placed to get the exact or possible costs after they assess the size of the space as well as the issues at hand. The crawl space encapsulation benefits will no doubt start manifesting themselves after a short while.

Pros of Crawl Space Encapsulation

Crawl space encapsulation helps to:

  • Prevent Mold and Mildew Issues: - when insulation prevents moisture from building up, mold and mildew issues are also avoided. Also, it will help to avoid wet and musty odors.
  • Improve Air Quality: - the process helps to promote clean air circulation in and out of your house. This makes it easier to breathe fresh air.
  • Eliminate Insect Infestation: - most insects like termites need moist grounds to survive, which makes humid crawl spaces their best choice for a breeding ground. When you encapsulate the crawl space, you dehumidify it destroying the pest breeding environment.
  • Thwart Structural Damage: - a moist crawl space may not be friendly to your home’s foundation. When you insulate it, however, you reduce moisture retention making your foundation more stable.
  • Increase Energy Efficiency: - with dampened air, your air conditioning unit is already overloaded since it has to fight the dampness. If the crawl space is insulated, however, the fight between the unit and damp air is eliminated. This reduces the energy it has to use, which translates into lowered monthly bills.

Cons of Crawl Space Encapsulation

The main crawl space encapsulation touches on the cost. That is:

  • Initial Capital: - depending on the size of the crawl space or structure, the initial capital may go higher than the projected one. The total cost, including the labor and supplies, may not be friendly to your pocket if your idea was for a small project.
  • Maintenance Costs: - after crawl space encapsulation, you may need to inspect it and run maintenance exercises often. The maintenance cost may vary depending on the number of features you need to work on as well as how often you do it. However, maintaining the protection levels will require professional assistance, labor, and newer supplies.
  • Cost of Upgrading the HVAC System: - encapsulating the crawl space reduces air movement in and out of the house. Therefore, if you have a combustion-based heater or furnace, they may not run smoothly unless you upgrade the current unit.
  • If your structure has wires and piping passing through the crawl space, you may not get through the encapsulation without interfering with them. To avoid ripping them out, you may need to call the respective electricians and plumbers to guide you through the safety measures involved. This will also cost you some extra dollars.
  • Also, leaving the wires and pipes in the encapsulated area will mean constant breaking of the capsule to access them. Due to the limited access, therefore, it becomes slightly expensive if repairs have to be done every time you rip the capsule.

Other cons include:

  • If you used to keep some of your supplies like paints, solvents, gasoline, and chemical cleaners in the crawl space, upgrading it means removing them from there. It will also force you to store them in places such as the garage which requires you to create extra storage at an extra cost.
  • Crawl space encapsulation also requires the skills of a professional. It may not be a good DIYer project unless you have the requisite skills.

Summary of Crawl Space Encapsulation: Pros and Cons

Whether you have problems or not, crawl space encapsulation pros and cons have given you a smart investment idea. Especially in areas that experience warm and wet climates, it will be a sound decision to encapsulate to prevent moisture from building up. The key point to consider is that the crawl space should be freed of any damage and existing moisture before encapsulation for maximum efficiency.

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1 thought on “Crawl Space Encapsulation: Pros and Cons”

  1. after reading about encapsulating a crawl space. i understand it’s purpose. i had my crawlspace encapsulated yesterday and i’m so glad i did! thank you.


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