Crawl Space Encapsulation

The Do’s and Don’ts of Crawl Space Encapsulation

Crawl spaces can often be a source of various issues in a home, including moisture problems, pests, and poor air quality. To tackle these issues, crawl space encapsulation has become a popular solution. Crawl space encapsulation involves sealing the crawl space with a vapor barrier and other materials to prevent moisture, pests, and outside air from entering the space. However, it’s important to follow certain guidelines to ensure the effectiveness of the encapsulation process. In this blog post, we will discuss the do’s and don’ts of crawl space encapsulation to help you make informed decisions.

crawl spaceWhat is a Crawl Space?

Before delving into the do’s and don’ts, let’s first understand what a crawl space is. A crawl space is an area beneath a house that provides access to the home’s foundation, plumbing, and electrical systems. These spaces are usually designed to be just tall enough for a person to crawl through and are typically vented to allow for air circulation and moisture control.

The Do’s of Crawl Space Encapsulation:

  1. Proper Ventilation: While it may seem counterintuitive, crawl spaces still require proper ventilation to avoid moisture buildup. Ensure your encapsulation system includes code-approved ventilation or special dehumidifiers to prevent excess moisture accumulation.
  2. Selecting the Right Materials: Use appropriate materials for crawl space encapsulation. Look for durable, moisture-resistant, and mold-resistant materials such as specialty vapor barriers, insulation boards, and dehumidifiers to ensure optimal results.
  3. Pest Control Measures: Seal all entrances to prevent pests such as rodents and insects from entering the crawl space. This will help keep the space free from infestations.
  4. Address Moisture Issues: If your crawl space already has moisture issues, more than encapsulation is needed to solve the problem. Address the underlying sources of moisture, such as outside humidity and moisture from the soil, before encapsulating.
  5. Ensure a Sealable Space: Before encapsulating, ensure no large air gaps or openings allow outside air to enter the space. Properly seal all openings, including vents, pipes, cracks, and other access points.
  6. Install a Drainage System: Encapsulation does not prevent water entry or flooding. To manage water effectively, install a drainage system that directs water away from the crawl space.
  7. Seek Professional Installation: Crawl space encapsulation is a complex process that requires expertise. Hiring a professional with experience in crawl space encapsulation is highly recommended to ensure proper installation and avoid costly mistakes.

The Don’ts of Crawl Space Encapsulation:

  1. Neglecting Proper Ventilation: Improper ventilation can lead to excess moisture buildup, promoting mold growth and causing other issues. Pay attention to the need for proper ventilation in your encapsulation system.
  2. Using the Wrong Materials: Avoid using materials unsuitable for crawl space encapsulation. Spray foam insulation, for example, can trap moisture and promote mold growth. Opt for materials recommended for this specific purpose.
  3. Skipping Pest Control Measures: Ignoring pest control measures can lead to infestations in the crawl space. Seal any potential entrances to prevent pests from entering and causing further problems.
  4. Overlooking Moisture Issues: If moisture issues exist, simply encapsulating the crawl space won’t resolve them. Address the underlying moisture problems before encapsulating for long-term effectiveness.
  5. Forgetting a Sealable Space: Encapsulation relies on creating a sealed environment. The encapsulation will only be effective with significant air gaps or openings. Ensure all openings are properly sealed.
  6. Neglecting a Drainage System: Water entry and flooding can still occur in encapsulated crawl spaces. To manage water effectively, include a drainage system in your encapsulation plan.
  7. Using Fiberglass Between Floor Joists: Fiberglass insulation performs poorly in crawl space environments. It absorbs moisture, loses its insulation value, and sags over time. Avoid using fiberglass between floor joists for crawl space encapsulation.

Why Encapsulate Your Crawl Space?

Moisture Control:

Moisture is a common problem in crawl spaces, leading to mold growth, wood rot, and musty odors. By encapsulating the crawl space, you create a barrier that prevents moisture from entering, keeping the space dry and reducing the risk of damage.

Improved Indoor Air Quality:

Unencapsulated crawl spaces can introduce damp and contaminated air into the home. By sealing the crawl space, you prevent the circulation of allergens, mold spores, and other pollutants, improving indoor air quality throughout the house.

Energy Efficiency:

Crawl space encapsulation can contribute to energy savings by preventing air leakage and reducing the workload on HVAC systems. Sealing the crawl space minimizes drafts and helps maintain consistent temperatures in the living areas, leading to lower energy consumption and reduced utility bills.

Pest Prevention:

Crawl spaces are attractive to pests such as rodents, insects, and termites. Encapsulation includes sealing off entry points and eliminating potential nesting sites, effectively preventing pests from invading the crawl space and potentially causing damage to the home.

Structural Integrity:

Excessive moisture in a crawl space can damage structures, including compromised foundations, sagging floors, and decayed wooden supports. Controlling moisture through encapsulation, you preserve the structural integrity of your home and increase its longevity.

Steps Involved in Crawl Space Encapsulation:

Assessment and Preparation:

A professional contractor will inspect the crawl space, identify existing issues, and recommend the appropriate encapsulation strategy. The crawl space is cleared of debris, and any necessary repairs, such as mold remediation or leveling, are performed.

Moisture Barrier Installation:

A heavy-duty moisture barrier, typically reinforced polyethylene, is installed on the crawl space floor and extended up the walls. This barrier acts as a vapor barrier, preventing moisture from seeping through the ground and walls into the crawl space.

Air Sealing:

All openings, gaps, cracks, and vents in the crawl space are sealed to prevent air infiltration. This includes sealing around pipes, wiring, ducts, and any other potential entry points for outside air.


Depending on the climate and specific requirements, insulation may be added to the crawl space walls or floor. Insulation helps regulate temperatures and further improves energy efficiency.


A dehumidifier may be installed in the encapsulated crawl space to maintain optimal humidity levels. This device helps control moisture and prevent the growth of mold and mildew.


Proper ventilation is essential for crawl spaces to prevent stagnation and promote air circulation. A balanced ventilation system or mechanical vents may be installed to ensure adequate airflow.


Regular inspections and maintenance are crucial to ensuring the long-term effectiveness of crawl space encapsulation. This includes checking the moisture barrier, dehumidifier, and ventilation system and addressing any issues.


Crawl space encapsulation effectively protects the home from water and air infiltration, improves energy efficiency, and reduces the risk of pest infestations. When done correctly, crawl space encapsulation can help keep your home dry, comfortable, and structurally sound. Be sure to hire a professional with experience in crawl space encapsulation for the best results.

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