An unencapsulated crawl space is not a good thing. For many homeowners buying a new home, out of sight is out of mind, for people purchasing an existing home it may not occur to them to have the crawlspace inspected. An unencapsulated crawl space can be a source of significant homeowner woes.
- Critters such as skunks, rodents, and raccoons.
- Pests such as termites, roaches, and other vermin.
- Humidity contributing to rot, fungus, and even toxic black mold.
- High utility bills for heating and cooling due to energy inefficiency.
- Foundation damage from water intrusion.
After seeing all the possible hazards and annoyances that come with an untreated crawlspace, encapsulation should be very high on the DIY list.
Materials for the Job
Materials for crawl space encapsulation include several types of insulation, dehumidifiers, ventilation, and a vapor barrier material. A Vapor barrier is one of the most critical factors in a successful job. A Vapor barrier is a high-density polyethylene sheet that prevents water intrusion while at the same time allowing water to escape instead of condensing and pooling.
Choosing the correct thickness of crawlspace vapor barrier material for the job is critical to success and understanding the thicknesses of vapor barrier will help to select the best possible material for your conditions and budget.
Understanding Mil
Mil is a measure of thickness equal to about one sheet of paper. The common plastic grocery bag is .5 mil thick. Considering which crawlspace vapor barrier material to choose is easy once you understand the thickness.
The very minimum thickness for a vapor barrier is three mil – or about the thickness of six grocery bags – while the top thickness is 20 mil. In between, you can find thicknesses of 6, 10, 12 and 15 mils in common usage. The thicker the barrier the more durable the encapsulation will be.
Pro Tips
Even for advanced DIYers, unexpected conditions with drainage and the foundation can derail even the most exactingly done job. Before you start, get an assessment from experienced professionals that can alert you to more advanced conditions and hazards at your job site.
