Crawl space moisture
When performing crawl space insulation efficiency is one of the biggest problems you’ll encounter. Efficient and effective crawl space insulation is a must if you plan on reducing the entry of pollutants, moisture, radon and other potential irritants.
Some of the problems you might encounter when planning a crawl space insulation are crawl space moisture,crawl space ventilation and another possible problem you might deal with is crawl space sealing. In this article we’ll only be talking about most common encountered crawl space moisture problems, don’t worry though as we’ll also talk about the rest of the problems in some future articles.
Crawl space moisture
Usually, a water-managed foundation system is used to drain rainwater and groundwater away from foundations. The picture below represents a water-managed foundation system. Although there isn’t a general rule for every crawl space, there are still a few things that apply in most cases and can help reduce crawl space moisture:
1. Your house should have sufficient rain drains - such as gutters - to conduct the rainwater as far away from your foundation as possible. ( number 2 in the picture )
2. Building a slope away from the house to facilitate the water drainage seems to work pretty good. A proper slope would be at a 5% grade for at least 5 feet away from your house, meaning at a minimum of 5 feet you should have a slope of 3 inches high ( 7,5 cm ) ( number 9 in the picture ).
3. Crawl space sealing is yet again a very important think when dealing with crawl space insulation. Air sealing can be done by simply adding a sill gasket.
4. Installing a protective membrane such as a EPDM-type membrane can greatly reduce the wicking of water from masonry walls.
5. Damp-proofing your masonry walls can prevent the wall from absorbing ground moisture by capillary action.
A very simple solution for all the crawl space moisture problems is the crawl space moisture barrier also called a crawl space vapor barrier. Sealing your crawl space from the ground and outside air is the solution in most cases contractors will only install a 6-mil non-UV resistant crawl space liner (a simple plastic liner).
Crawl space moisture barriers can be found at almost any hardware store that’s specialised in insulating materials. Before you purchase anything, be sure to discuss with your contractor.
