Expert: Richard Taylor, AIA - 8/26/2005

Question
We have neighbors in Wyoming who are in the process of making plans to build a home.  A question has come up regarding garages.  A lot of homes in this area have attached garages that are below the level of their home - some just a few feet, some deeper.  Our question is if it is necessary that garages are lower than the level of the house.  If it is, what is the reason to have it lower?  Thank you!

Answer
Hi Tricia - thanks for your question!

What's going on isn't that the garage is lower, it's that the house is higher.  Building codes require that the wood floor system of the house is at least 8" above the grade - and since most floor systems are about 12" thick, that puts first floor levels at least 20" out of the ground, sometimes more.

The garage floor needs to be closer to the ground (obviously!) so there's your difference.  On sloped lots, the difference can be quite large.  Generally, houses with attached garages should be sited with the garage on the "high side" of the lot to raise the garage level and reduce the number of steps from the house to the garage.

Occasionally the architecture of the house causes a greater difference.  In a classic Georgian, for example, the first floor might be 3 or 4 feet above the ground - which creates a drop of 5 or 6 steps to the garage.

Although it's been changed in many places, some building codes require that the garage floor be at least 7" lower than the house floor to prevent gas fumes from seeping into the house.

Hope this helps!

Richard Taylor, AIA
Richard Taylor Architects, LLC
www.rtastudio.com
www.betterhomedesign.blogspot.com