Waterproofing a crawl space is necessary for the health and safety of your household. There are various things that go into ensuring a crawl space remains dry. However, none is as important as the moisture barrier. Unfortunately, not many people give it too much thought.

Moisture barriers are the heart and soul of crawl space waterproofing. They come in different options in order to meet the varying needs of homeowners. The most common options include:

  • Reinforced barriers: As the name suggests, these vapor barriers are reinforced with a material to make them more resistant to mechanical damage. These specially engineered plastic sheets offer you the greatest value for money. They are durable and will provide you with the longest service life. They are also highly resistant to mechanical damage and will therefore keep pests and the elements out of your crawl space.
  • Coated woven liners: These may be considered as barriers to moisture but are mostly used as vapor retarders. They consist of thin woven polythene ribbons that are coated with a layer of clear polythene 2 millimeters thick. The woven ribbons lie at the center of the sheets. These ribbons give strength to the sheets making them resistant to mechanical damage.
  • Unreinforced polythene: These barriers are made of polythene. However, they do not contain reinforcements like the reinforced barriers. They are therefore less durable and are prone to tearing. It is not advisable to use these as a long term solution for the encapsulation of your crawl space.
  • Plasticized aluminum: This is one of the newer products in the market. It is made of a plastic sheet with an aluminum layer. The sheet also includes a thin coated liner of woven material. These sheets are highly durable and offer great value for money because of their great performance.


As you consider the type of moisture barrier to invest in, it is important to also consider the current state of your crawl space. If your crawl space has been neglected for a long time, you may want to consider parging.

Parging is the process of adding a layer of cement on the walls of the crawl space. This ensures that any voids in the walls are filled in. This keeps moisture out even after encapsulation of the crawl space. It is advisable to parge your crawl space walls especially if they are constructed from stone.

The most important first step is to contact a professional. Don’t wait until it’s too late!