The Importance of Airtightness
April 14, 2020 at 4:00 AM
by TAG Panels
energy efficient walls bc

A building enclosure is a system of materials, components and assemblies that, when combined, create critical barriers that separate the exterior and interior environments. An air barrier is one of the most important critical barriers and represents a building's resistance to air leakage.

Air transports a variety of elements from moisture and heat, to noise and airborne contaminants and if left unchecked, can lead to an uncomfortable and inefficient home.

To highlight the importance of air barriers, new regulations from the BC Energy Step Code have made airtightness a mandated criteria for all new builds with increasing air tightness targets for home builders to meet. Blower door tests are conducted on the building post construction to ensure it meets the necessary standard.

In order to achieve these targets, it is important to understand how an air barrier works and the different elements that interact with it.

Source: BC Housing - Achieving airtight buildings (2017)

Air barriers need to be continuous from one building element to the next. If air is allowed to leak through the building envelope, especially warm moist interior air, it can condense on cold surfaces such as framing members or sheathing leading to the development of mould and rot.

Air leakage can transport significantly more moisture than vapour diffusion. Studies have shown that a 25mm x 25mm hole in an air barrier has the potential to transmit 30 litres of water per heating season through air leakage. When compared to vapour diffusion, only 0.33 litres is transported through the same wall assembly.

Source: BC Housing - Achieving airtight buildings (2017)

Air leakage can lead to significant heat loss through the building envelope. It can also reduce the effectiveness of even the most high performing insulation materials by as much as 75%, resulting in higher energy consumption and increased homeowner costs.

How to create an effective air barrier

Having a clearer image of how the building structure and its critical barriers go together is imperative. A 3D model can help identify problematic air barrier details early on in the project. As part of the TAG Panels design process, a 3D model of the structure is created showing every wall, floor, and roof connection, the integration of rough openings, and how balconies, decks and canopies are connected. The model can be used to identify the air barrier, and other critical barriers, and help maintain their continuity throughout the building.

Prefabricated wall systems have the advantage of creating a designated service cavity on the interior side of the wall. This cavity effectively isolates the services away from critical barriers and limits unintended penetrations from trades during construction.

Cutaway section through a TAG 3 prefabricated wall panel with isolated interior service cavity

Using high quality products that will last the test of time is an easy way of creating an effective air barrier. TAG Panels use the highest quality membranes and tapes; Solito Mento 1000 as our primary air barrier sealed with Proclima Tescon Vana tape. Unlike solvent based acrylic tapes, such as tuck tape, high performance tapes are solid acrylic based meaning they will not dry out and crack over time.

Creating a continuous and effective air barrier is one of the easiest ways to create a healthy, comfortable and high performing home. See some of our tips below for your next project.

Tips for creating a high performance air barrier:

  • Continuity
    • Plan ahead and identify problematic locations and details. A 3D model can help illustrate this.
  • Designate an “Air tightness champion” on site.
    • An individual on site to oversee the integrity and maintenance of the air barrier.
  • Get your trades on board, early
    • Educate your trades on the importance of critical barriers and how they can help maintain them
  • Conduct multiple blower door tests
    • A blower door tests the effectiveness of your building's air barrier. Multiple tests at different stages throughout the build process will help identify any leaks before moving on to the next stage of construction.
  • Use high quality products that perform better and last longer

If you are interested in learning more about TAG Panels design process, the panels we build and the products we use, head on over to our website, drop us a message or feel free to stop by the factory for a visit.

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