The Role of Vapor Barriers in Controlling Dampness

What is an acceptable damp reading?

Damp readings are expressed as a percentage of moisture content in the material being measured. An acceptable damp reading for most building materials is below 15%. Readings above 15% indicate the presence of excessive moisture that can lead to mold growth and other problems. Vapor barriers are an important part of a building's envelope. They help to control the movement of moisture vapor through the building assembly, preventing it from reaching the interior of the building where it can cause damage. Vapor barriers are typically installed on the warm side of the building envelope, which is the side that is most likely to be exposed to moisture vapor. There are a variety of different types of vapor barriers available, each with its own advantages and disadvantages. Some of the most common types of vapor barriers include: * **Polyethylene:** Polyethylene is a plastic film that is commonly used as a vapor barrier. It is inexpensive and easy to install, but it can be easily torn or punctured. * **Asphalt-saturated felt:** Asphalt-saturated felt is a paper-based material that is coated with asphalt. It is more durable than polyethylene, but it is also more expensive. * **Foil-faced insulation:** Foil-faced insulation is a type of insulation that has a layer of aluminum foil on one side. The foil acts as a vapor barrier, preventing moisture vapor from passing through the insulation. The type of vapor barrier that is best for a particular application will depend on the climate, the type of building, and the budget. It is important to consult with a qualified professional to determine the best type of vapor barrier for a specific application.

Benefits of Using Vapor Barriers

There are a number of benefits to using vapor barriers in buildings, including: * **Reduced moisture damage:** Vapor barriers help to prevent moisture from reaching the interior of the building, where it can cause damage to building materials and furnishings. * **Improved indoor air quality:** Vapor barriers help to reduce the amount of moisture in the air, which can improve indoor air quality and reduce the risk of mold growth. * **Increased energy efficiency:** Vapor barriers help to keep the interior of the building warm in the winter and cool in the summer, which can reduce energy costs.

Conclusion

Vapor barriers are an important part of a building's envelope. They help to control the movement of moisture vapor through the building assembly, preventing it from reaching the interior of the building where it can cause damage. There are a variety of different types of vapor barriers available, each with its own advantages and disadvantages. It is important to consult with a qualified professional to determine the best type of vapor barrier for a specific application.