Expert: Daniel Humphrey - 1/14/2012

Question
I'm building a 2-car garage (24 x 24) and I'd like to turn the upper level into a studio apartment.  Obviously I will have to follow the building code, but do you have any advice to offer about the undertaking -- in particular with regard to safety (keeping car exhaust fumes out) and sound-proofing?

Answer
Curtis,

Mainly, make sure the floor between the two is airtight. You have a chance to seal the floor layer from both above and below during construction. Then you can insulate and install sheetrock on the ceiling and walls of the garage, making sure the seams are taped and all gaps are caulked. This will also help with sound.

If you have an interior stairway connecting the garage to the second floor above, make sure you have doors at both levels that can be shut. Inside the stairway, as high as possible, have windows that can open. This will provide a chimney effect that can draw fumes from the garage out. For a connecting stairwell, consider a pop-out about 8 feet wide by 10 feet long, and at least as tall as the main roof; this will provide ample air movement and encourage the chimney-effect ventilation.

A good exhaust fan in the garage can help clear the air. Some are set with the garage door opener to automatically run for a period whenever the door has just been closed.

Daniel