Expert: Dan Griffin - 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
Curt, having a room, often a bed room, over a garage is very common.  There are usually not any particular steps taken to do this.  My sister had a home with this arrangement and she did say that it was harder to keep that room warm as the garage was not conditioned.  I am not aware of any fume or smell issues, many garages are attached and I don't notice a change of smell due to cars - I do notice a change if that is the designated smoking, beer drinking, painting venue.  My boy has that with two bedrooms above with no apparent issues, not even heat loss.

If you were planning to run the vehicles for extended time inside the garage, an exhaust fan and/or carbon monoxide hose to the outdoors would be warranted.  
This is quite common at mechanics garages, though usually only done when the weather demands having the doors closed.  I would spend extra effort on insulating which would help the HVAC and sound.