Seal the Deal Prolong the Life of Your Building by Air Sealing Your Multi-Family Property

Suzanne White

{Editor’s Note: This article is reprinted with permission from the September 2016 issue of the RHAWA Current monthly newspaper.}

It’s a maintenance request you never want to get—there are leaks in your building. You may not be able to see, hear, or even feel them. These leaks can negatively impact resident comfort, affect indoor air quality, and create mold nightmares.

Your building could be leaking air—possibly a lot of air.

According to a 2006 study by the Lawrence Berkeley National Laboratory, multi-family buildings are “about two times as leaky as single family detached homes per unit surface area.” This means an opportunity to increase the energy efficiency of your multi- family property, and potentially save on long-term operating costs — all while extending the life of the building. But what are the advantages, and how exactly do you plug all the holes?

The solution is to air seal the property, which greatly reduces air seepage through identifying and filling leaks. You can reap the benefits that come with a more air-tight building, including better control of air flow, which can minimize mold, and improved heat retention and resident comfort.

Air sealing is not a new practice, at least for single family homes. Multi- family air sealing is just catching on, and can be a different animal.

Some contractors say one of the biggest challenges of working on a multi-family property is just that — the number of people. It can be difficult to work amongst and coordinate with so many people, but it is well worth it for the savings the property will see from this process.

Because multi-family air sealing is more complex than single family air sealing, it is important to find a qualified contractor.

12 Community Associations Journal | April 2017

Your contractor will first depressurize each unit to identify leaks. In this step of the process, known as a blower door test, large infiltrometer fans are fitted on the exterior doorways of the property. Fans suck air from inside the space, causing exterior air to be sucked in through any leaks in the exterior, or envelope, of the building. Residents can be in their units during this test, as this suction action is safe and unnoticeable. The fans calculate a leakage rate, measured in cubic feet of air per minute (CFM), which provides a baseline reading for your building and gives insight into where air is escaping. According to the U.S. Department of Energy, common leakage areas include parts of the attic, holes cut to allow for plumbing or electrical work, places where renovations interrupt the original seal of the building, and gaps between the structure and doors/windows.

Once leaks are located, contractors have two main ways to address them: using foam to manually seal leaks, and filling the walls of the envelope with extra material where needed. This involves making minor incisions in the exterior walls, just large enough for a hose to pump in cellulose fiber to create a more densely packed wall. The holes are then closed up and the siding is returned, with little to no impact on the look of the building. When the sealing is done, a final blower door test is performed to measure the new air leakage rate. A two story, six-unit building can take an average of five days to complete.

If the property doesn’t already have ventilation fans, some must be installed in order to control air flow. By ensuring each unit has a ventilation fan programmed to run at least eight hours a day or 20 minutes per hour, and by reducing unwanted air infiltration, indoor air quality is improved.

No official studies have been done on the connection between an air sealed building and a higher tenant satisfaction rate, but initial feedback points to a tight correlation.

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