Vapor Barrier Installation: Why Do I Need A Vapor Barrier?

What is a vapour barrier?

When used as damp proofing, vapour barriers (sometimes called vapour retarders) are typically plastic or foil sheets used to prevent condensation from forming between assembly members such as walls, roofs, foundations, etc. For example, vapour barriers can be used in a typical commercial building or house to make it more energy efficient and comfortable, while also preventing moisture problems.

What are vapour barriers for?

Construction of a building requires a vapour barrier. Water vapour can condense on wall, ceiling, attic, crawl space, or roof surfaces, which can lead to rot and mould growth.

Even the most solid of buildings can be damaged by condensation caused by water vapour movement (called “water vapour drive”). This can render the insulation ineffective. Educating yourself on the when, how, and why of installing a vapour barrier can avoid this costly headache.

What is water vapour?

As liquid or solid, water vapour is a gas. It is totally invisible. The warm, humid interior of a house continuously diffuses water vapour to the exterior, which is cold and dry. Whenever water vapour passes through a wall, ceiling or other barrier and meets a surface with a lower temperature than the dew point (where water vapour condenses), this is known as condensation and represents a threat to the integrity of your building materials.

Are you planning to build in a cold climate? Consider this.

Vapour barriers may be questioned by some people. If you are a builder, your first step should be to check your local and provincial building codes. Many colder climates in North America require the installation of vapour barriers in buildings.

In warmer climates, vapour barriers may not be necessary. A vapour barrier can harm the building materials or cause more harm than good if used in the wrong climate. Water vapour may be prevented from drying because of this circumstance, which can result in rot and mold.

Consult with experienced contractors for vapor barrier installation in San Antonio if you are uncertain about the building requirements or have your building needs calculated based on established criteria from professional groups. 

America Air Duct Cleaning recommends that roofs be fitted with vapour barriers on their interior sides in climates where the outside average temperature in January is below 40 degrees F (4 degrees C) and the expected interior relative humidity is greater than 45 percent.

Do I need a vapour barrier?

Depending on the climate where you’re building as well as the building’s intended use, you can decide if a vapour barrier is necessary on the entire building envelope and roof. Choosing an appropriate vapour barrier must be carefully considered prior to the construction phase, as it will promote energy efficiency as well as the longevity of all building materials. 

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