What are moisture barriers? Is there a difference between moisture and vapor barriers? Keep reading to find out! Plus, keep reading to learn more about…

  1. Moisture vs. vapor barriers
  2. Air barriers
  3. Types of vapor barriers
  4. The importance of moisture barriers

Moisture vs. Vapor Barriers

A common question we hear in this industry is: what’s the difference between moisture barriers and vapor barriers? The quick answer: they’re basically the same thing. Moisture barriers and vapor barriers are both types of building materials that are meant to stop water from getting past a certain point (a barrier). Typically speaking, “vapor barrier” is more commonly used now. It’s important to note that no vapor barrier is capable of stopping all moisture.

The next question people usually ask about moisture/vapor barriers is the difference in them and air barriers. This does have a distinct purpose, though air barriers are still pretty similar to moisture/vapor barriers. Sometimes vapor barriers are not always a good idea, but air barriers usually are. Just like insulation, air barriers control the movement of air that has moisture in it. This doesn’t fully stop moisture, but instead, allows the moisture to disperse. There are many different materials that make up these barriers, and they provide a self-contained pocket of air to control the movement of thermal energy in and out of a building. Typically, air barriers and vapor barriers will be used together to make a building more energy efficient. This, in turn, will expand the life of a building.

Air Barriers

Air barriers are another term in the building industry that is similar to a moisture barrier, but a bit different. Air barriers are necessary all the time in a building, but vapor barriers are not. Like insulation, air barriers control the movement of air with moisture in it. This does not stop the moisture altogether, but instead allows for it to be dispersed appropriately. Air barriers are made of different materials, and they provide a contained amount of air to help control the movement of energy in and out of a building. Typically, air barriers are used with vapor barriers to increase the efficiency of energy use.

Types of Vapor Barriers

There are also many types of vapor barriers, which are made from many different types of materials. For example, rigid foam insulation is a relatively effective vapor barrier that’s commonly used. Polyethylene plastic is another common type of vapor barrier, because it has one of the least amounts of measured moisture permeability. Vapor barrier paints and primers are specially designed, and they can sometimes be applied to materials like bricks to provide an adaptable vapor barrier. Aluminum foil successfully blocks moisture, but this is less commonly used because it’s not a material that’s practical to use.

Vapor and moisture barriers are often recommended by construction workers, but for different reasons and in many different circumstances. Vapor barriers can be applied to interior walls which are mainly cold. They are best applied to exterior walls in mainly hot climates though. Usually, vapor barriers will be installed in finished basements between the concrete and the floor treatment. This helps to prevent damage from leaks.

The development of vapor barriers over time now allows builders to install hardwood floors in places that are regularly damp like basements. Many construction workers recommend vapor barriers; they’re applied to interior walls in climates which are mostly cold, while in hotter climates, they work best when they’re applied to exterior walls. Finished basements usually receive a vapor barrier layer between concrete and the floor, which works to prevent damage from rain or other moisture.

The Importance of Moisture Barriers

Moisture barriers are incredibly important, as they aim to keep water in all forms out of your home. But vapor barriers also let water out of your home if it gets in your home in the first place. It’s important to remember that water can come in your home in several different ways: as a liquid, a solid, a vapor, and adsorbed (not to be confused with absorbed).

In the liquid form, water comes into your house from rain and ground water. You must drain water out of your home if it gets in, or else mold will grow in your home and cause damage.┬áThe solid form of water can affect your home in the form of snow or ice. If water is not already solid when it enters your home, don’t let it get solid. If it does, though, give it space to thaw. Water in the form of vapor is hard to control, but sometimes the best strategies to keep water vapor out also trap water vapor inside.

Climate has a great affect on water vapor and moisture barriers in your home. Vapor barriers slow the migration of water vapor in your home. It is easy to confuse vapor barriers and air barriers, because air usually holds a lot of moisture in the vapor form. So when air moves from location to location because of an air pressure difference, the vapor moves with it. Technically, air barriers are also vapor barriers when they control the movement of air with moisture in it.

At Alamance Insulation and Gutters, we can help you understand moisture barriers.. One of our many services is installing moisture barriers in your home. Serving many areas in eastern North Carolina, we specialize in providing quality products and expert services to meet the unique needs of our customers. We offer services to help both homeowners and builders alike.