Air & Water Barriers

Air and water barriers are essential components of building envelope systems that protect buildings from moisture and air infiltration. They are critical for ensuring energy efficiency, comfort, and indoor air quality. These barriers are installed in the walls, roofs, and foundations of buildings, and they prevent air and water from penetrating through the building envelope. In this essay, we will discuss the importance of air and water barriers, the different types of barriers, and how they are installed.

Importance of Air and Water Barriers:

Air and water barriers are critical for the long-term durability of buildings. When moisture and air penetrate through the building envelope, they can cause a range of problems, including mold growth, rot, and deterioration of building materials. This can lead to costly repairs and health problems for occupants. Air and water barriers help to prevent these issues by creating a continuous, impermeable layer that keeps moisture and air out of the building.

In addition to protecting the building from moisture and air infiltration, air and water barriers also play a critical role in energy efficiency. By preventing air leakage, these barriers reduce the amount of energy required to heat and cool the building. This can lead to significant cost savings over the life of the building.

Types of Air and Water Barriers:

There are several types of air and water barriers, each with its own advantages and disadvantages. The most common types of barriers include:

1. Building paper: Building paper is a traditional air and water barrier that is made from asphalt-saturated felt. It is typically installed on the exterior of the building, and it provides good water resistance. However, it is not very effective at preventing air leakage.

2. Polyethylene: Polyethylene is a plastic sheeting that is commonly used as a vapor barrier in walls and roofs. It provides excellent air and water resistance, but it can be difficult to install correctly, and it is not very durable.

3. Rubberized asphalt: Rubberized asphalt is a liquid-applied air and water barrier that is sprayed onto the building envelope. It provides excellent air and water resistance, and it is very durable. However, it can be difficult to install, and it is more expensive than other types of barriers.

4. Spray foam insulation: Spray foam insulation is a popular air and water barrier that is used in walls and roofs. It is sprayed onto the building envelope, where it expands to fill gaps and cracks. It provides excellent air and water resistance, and it also provides insulation. However, it is more expensive than other types of barriers, and it can be difficult to install correctly.

Installation of Air and Water Barriers:

The installation of air and water barriers is a critical component of building envelope design. Improper installation can lead to air and water infiltration, which can cause a range of problems. The installation process varies depending on the type of barrier being used, but there are some general principles that apply to all types of barriers.

First, it is essential to ensure that the building envelope is clean and free from debris. Any dirt or debris on the surface of the building envelope can prevent the barrier from adhering properly, which can lead to air and water infiltration.

Second, the barrier must be installed in a continuous, uninterrupted layer. Any gaps or seams in the barrier can allow air and water to penetrate through the building envelope. The installation process should be carefully planned to ensure that the barrier is installed without any breaks or gaps.

Third, it is critical to follow the manufacturer's installation instructions carefully. Different types of barriers have different installation requirements, and failure to follow these instructions can result in a barrier that does not perform as intended.

Finally, it is important to test the air and water barrier after installation to ensure that it is performing as intended. This can be done using a variety of methods, including blower door testing for air