Crawl Spaces Encapsulation


Wet crawl spaces pose a real danger to the health of the occupants of a dwelling and the structural integrity of the building.

What are the symptoms of a wet crawl space?

  • Presence of mold
  • Allergies 
  • Presence of water or wet concrete
  • Persistent humidity and bad odors
  • Condensation
  • Rotten wood
  • Sagging beams and joist
  • Insects and vermin infestations
  • Hight energy consumption

What can cause high humidity in a crawl space?

A dirt floor is an infinite source of moisture in a crawl space. As the moisture evaporates into the air, the humidity also increases.

The second main cause of high humidity is the outside air. For example, when the outside temperature is 32 Celsius with 60% relative humidity and it enters a cool crawl space of 23 degrees, then the relative humidity will increase to 95%.

The solution?

  • Drying
  • Sealing
  • Dehumidify

1. Dry the crawl space

Drying the crawl space is the first phase of a good process of cleaning the air and protecting the building.

Drainage: the optimal drainage technique should be chosen bases on its situation. Sometimes it is necessary to install a drain system and a sump pump.

2. Sealing the crawl space

 Drainage is not enough to prevent moisture from being in the crawl spaces. The soil remains moist and this moisture is transmitted to the air.

A crawl space vapor barrier: Bisson Expert and his partner SafeBasement have developed a unique and efficient sealing technique to cover the entire floor and walls of crawl spaces. This vapor barrier with welded joints forms an envelope that cuts off the transfer of humidity from the soil and foundations. 

This 22mil white VPS vapor barrier is very robust and washable. It is designed to be placed directly on the soil and foundation walls providing a clean, durable, bright and healthy finish.

3. Dehumidify the crawl space

Despite draining the water and sealing of the crawl space, condensation of moist air during the summer can cause mold to occur on the wood structures.

The situation is amplified when hot and cold meets, which is very common along the foundation walls in the summer and winter.

In addition, in summer, moisture can come from warm, moist outdoor air that condenses in the cooler crawl space.

Air treatment: an air system that provides dehumidification is often recommended to reduce humidity and improve the air quality.

Picture description

The pictures on the right represent different stages of the crawl space encapsulation process. The first picture shows a crawl space where humidity is too high. The second picture is about the vapor barrier installation in progress. In the third picture, the installer is using a specially formulated caulking to seal the vaper barrier to the foundation wall.

Picture of a crawl space that has been encapsulated.

Crawl space encapsulated result