FAIRBANKS —  Q: I want to build a garage. What are the advantages of having an attached garage versus a detached garage?

A: First, think about why you want a garage. To park a car and store a few boxes, to park two cars and have a workspace for weekends? How much space do you need? 

Depending on the shape and size of your lot, the decision may be very easy, especially if the garage will only fit in one location. After you consider how big you would like the garage to be, get a tape measure and physically mark where the garage might fit on the ground outside your house.

Will this location make sense for your lot, whether it is attached or detached? Assuming you are planning to park a car in the garage, look at the road access from the proposed location and make sure it’s feasible to extend your driveway. Think about how you will back your car out of the garage: is there space to turn around or will you have to back into the road? Will you need to grade the ground under the garage to allow good site drainage? If the garage is attached to your house, how will it affect the house profile?

If your lot is big enough to accommodate either an attached or a detached garage, then it makes sense to evaluate your needs carefully. The biggest advantage of an attached garage is convenience. You are adding a place to park a car and store extra items right to your house. On the other hand, the biggest disadvantage is the dangerous fumes emitted by vehicles and some items commonly stored in a garage — such as fuel or paint.

Every time you start your car or drive back into the garage, you are introducing carbon monoxide and other harmful combustion gases into your building enclosure. These gases can seep into the living space. Shared walls or ceilings between the garage and home should be extremely well air-sealed. 

After construction, verify that all carbon monoxide detectors in the living spaces are functioning properly. Be aware that off-the-shelf CO detectors have a life span, so check the specs on your model. Also, keep in mind that even if the carbon monoxide detector is functioning properly, residential models are usually calibrated to avoid nuisance alarms. This means low levels of CO can enter the home and remain undetected.

Ventilating the garage directly is an option. One effective method is to install a bathroom-type exhaust fan ducted to the outside. This fan can be wired to a motion sensor with a timer. When the sensor detects movement at the garage door, the fan can purge the air out of the garage for a set period of time. Localized ventilation systems of this type should be sized and installed by a professional.

Attached garages have some other advantages besides convenience. If you would like a washing machine or sink in your garage, having it attached to the house makes it easier to plumb. And of course, one wall is built, which means buying fewer construction materials. However, one consideration, especially for older homes, is how you will match the aesthetic of your home when building the garage. Is the same siding or paint color still available? If not, can you find an acceptable alternative? Most people want an attached garage to look the same as the exterior of their home, and to match the home’s profile.

Detached garages also have advantages. For one, gases from cars or stored items will not be able to enter the home. You’ll certainly still need to ensure the garage has adequate ventilation, but you don’t have to worry about combustion gases or fumes entering the house. Also, if the garage is being used as a workshop to repair cars, do carpentry or play drums, a detached garage separates the noise from the home. If you’re thinking about expanding the garage one day — adding a patio or extra storage on top — then a detached garage provides more flexibility. 

Running power to a detached garage can be a challenge. Be sure to contact your local power company before construction if you need a new service to make sure  it is possible to make the connections.

Regardless of the type of garage you install, paying attention to energy efficient construction will pay off in the long run. If you plan to heat the garage, adding adequate insulation to the walls and floor will ensure lower heating bills. And it’s very important to include mechanical ventilation to ensure dangerous gases do not stay in the garage space or enter the home.

The “Ask a Builder” series is dedicated to answering some of the many questions Fairbanks residents have about building, energy and the many other parts of home life. 


Ask a Builder articles promote home awareness for the Cold Climate Housing Research Center (CCHRC). If you have a question, contact us at info@cchrc.org or 457-3454.