With the right kind of vapor barrier installation, even vented crawlspaces can be completely enclosed. There is a range of thicknesses for vapor barriers, from 6 mil to 20 mil, with 6 mil being the absolute bare minimum and 20 mil being the heaviest duty and most puncture-resistant option.

In relation to the vapor barrier for the crawl space, what are two measurements that you need to be familiar with?

When selecting your poly for the crawlspace vapor barrier, there are two measurements that you should be familiar with. The thickness of the polymer is denoted by the term "mils," and the term "perms" refers to its permeability to moisture. Mils: The thickness of one mil is equivalent to 0.001 inch. Most building codes for residential applications specify a minimum thickness of 6 mils (0.006 inches) for the reinforced poly vapor barrier. However, it recommends 10 mil or higher for applications that take place in crawl spaces. It provides a range of thicknesses from 1 mil all the way up to 20 mil. The water vapor permeability rating, or perm rating, indicates how easily a material will allow water vapor to pass through it. When it comes to permeability, a material's perm rating speaks volumes about how well it does its job. A material needs to have a perm rating of 0.1 or lower in order to be considered a vapor barrier. This bare minimum requirement is satisfied by poly sheeting that is at least 6 mils (0.06 perms) thick.

What are some of the qualities that define an effective vapor barrier for crawl spaces?

The thickness of the polymer that you decide to use will be primarily determined by two factors: use of the crawlspace for various purposes (including maintenance and storage, for example). The ground or other material that makes up the crawlspace's floor.

How do you figure out the total square footage that needs to be covered by the vapor barrier in the crawl space?

Your first order of business is to calculate the amount of poly sheeting required to cover your crawlspace. Remember to order enough fabric so that the seams will overlap by between 6 and 12 inches. The majority of foundation walls can be effectively covered by a roll that is six feet wide, but you should consider using a roll that is wider than that for the floor. Floor area equals length times width, while wall area is calculated by multiplying length and width by two. Remember to factor in the overlap of 6 to 12 inches; the total should equal the wall plus the floor.

Is it a smart move to install a vapor barrier?

Inside buildings, vapor barriers protect against the growth of mold and rot by preventing the buildup of condensation and moisture, both of which can be harmful to the structural components of a building. When constructing a house in an area with a high relative humidity, installing a vapor barrier can serve as an essential line of defense against issues that are brought on by an excess of moisture.

Does the vapor barrier keep heat in?

In both cases, the vapor barrier is tasked with preventing warm, humid air from shedding its moisture as it meets a cool surface, no matter which direction it is travelling in. The fact that there is no one set rule regarding vapor barriers is the single most important realization to make.