Now, I’m not a card-carrying Buddhist but I’ve read a bit about that wisdom tradition and I admire its practitioners. I am though a card-carrying home inspector and have been one for about 20 years. Over those two decades, I’ve noticed that some of the principles of the Dharma (Buddha’s teachings) can be applied to the process of inspecting homes. One of those principles, non-attachment, means that one should not attach oneself to outcomes, to fame, to fortune, to pleasure, etc. lest this lead to Dukkha (usually translated as suffering or dissatisfaction).
One kind of non-Buddhist attachment that we see during some of our property evaluations takes the form of an attached or built-in garage. The ‘attachment’ in this context is the shared walls or ceilings between the parking garage in the living space around it. A built-in garage differs from an attached garage in that a built-in garage will have some living space above it and an overlapping footprint with the home while an attached garage merely shares a common vertical wall (called a demising wall) with the living space.
Gaps in shared walls or ceilings between these garages and the living space of the home constitute a “failure to provide a properly configured air/thermal/fire barrier”. The “suffering” that this condition often causes to homeowners can take multiple forms including but not necessarily limited to; energy losses, drafts, cold walls or ceilings, and reduced indoor air quality including carbon monoxide intrusion from vehicle exhaust. In the relatively unlikely but extremely unfortunate event of a fire in the garage, these gaps can allow toxic smoke and fire byproducts as well as the fire itself to extend rapidly into the living space of the home. Obviously, this could be a major cause of real suffering.
According to FEMA, there were approximately 6,600 residential garage fires, 30 deaths, 400 injuries, and $457 million in property damage from residential garage fires for the period between 2009 to 2011. 40% of these fires extended from the attached or built-in garage into the occupied portions of the dwelling causing major damage. Since few, if any American building codes require the installation of smoke alarms inside residential garages and since garages often contain gasoline, vehicles, and other high fire load materials, fires in garages may not be noticed until they are in an advanced stage and are beyond the capability of the average homeowner to combat using handheld extinguishers.
In addition to the increased fire risk presented by attached or built-in garages, they are also prone to a significant diminution of indoor air quality and indoor air comfort. The compromised air/thermal/fire barrier often present at these properties allows gasoline vapors, pesticide off-gasses, and other chemical contaminants to be drawn into the air that the occupants breathe. Most homes are under negative pressure during significant portions of the day via the use of kitchen exhaust fans, bathroom exhaust fans, clothes dryers, furnaces, water heaters, and fireplaces….all of which pull air out of the home during their operation. The negative pressure created by the operation of these components will cause air to be sucked into the home from the paths of least resistance. If the garage is not properly sealed off from the living space that path can be slowly sickening or devastatingly deadly.
We recommend that every homeowner who lives in a home with an attached or built-in garage perform a simple, do-it-yourself test to determine if significant air/thermal/fire breaches are present. While the steps of this test can vary depending on the features of the home in question, the general process goes like this. All of those components listed above which create a negative pressure in the home should be put into their operating condition. That is the exhaust fans, furnace, water heater, fireplace, etc. should all be activated. This will create a close approximation of a worst-case scenario under which air could be drawn from the garage into the living space.
While these appliances and equipment are in operation the homeowner should utilize a smoke pencil (under $40 and available here https://www.toolexperts.com/smoke-pen-pencil-tests-air-flow.html) to trace a path around the perimeter of the hinged door between house and garage, along the base of the demising wall between the house and garage, and around any can lights or other penetrations of the drywall ceiling in a built-in garage. If you see smoke from the smoke pencil being pulled toward the living space then you know you need to perform air-sealing.
Air-sealing is the practice of stopping air from moving into, through, or out of places where we want to keep that air inside. Caulking is an obvious method of air-sealing gaps and cracks while dense packing of cellulose or rock wool insulation is one that many homeowners may not be aware of. Having a qualified insulation contractor blow insulation under pressure into the joist framing channels at the garage ceiling or into the stud channels of the demising wall cannot only the movement of energy but can also eliminate air movement through these common breaches in the air/thermal/fire envelope. In the event of a fire in the garage, the blown in insulation in the framing channels could provide a life-saving barrier to the movement of smoke, flame, and super-heated gases into the rooms adjacent to the garage.
The carbon monoxide detectors purchased at most retail outlets and found in most dwellings are not capable of detecting lower levels of carbon monoxide or carbon monoxide introduced into the home for briefer periods of time. Levels of carbon monoxide below the detection limits of these lower-priced units can still be harmful to occupants, especially infants, the elderly, and those with existing medical conditions. In order to further reduce the risk of indoor air contamination homeowners may opt to install an exhaust fan (Energy Star rated of course) in the attached or built-in garage thereby further reducing the risk for air transference into the home and the resulting air contamination. Installing louvered vent panels in the overhead garage door would be an easier way to achieve ventilation to the exterior without incurring the not totally inconsequential electrical energy penalty of an exhaust fan.
As the Swiss-French architect, Charles-Édouard Jeanneret also known as “Le Corbusier” famously stated, “a house is a machine in which you live”. Most of us live in machines with which we are not adequately familiar. Knowing how the various components and systems of your home operate and interact is the purview of a multidisciplinary group of individuals known as building scientists. Home inspectors, together with architects, HVAC contractors, weatherization contractors, and others should be well-versed in building science and should be able to provide their home purchasing clients with the information necessary to make their home safer, more comfortable, more durable, and more efficient. We at Domicile Consulting relish the opportunity to assist homeowners with the solution of energy, comfort, safety, and indoor health issues either by phone, email or via our website chat function. Contact us today to get started.