chueh,
Thank you for the explaination. The garage is not living space, so it is not counted when placing the grid over the house, and this is the same with the deck. If the entrance is a cloesd space and part of the house, count it. But if this is a covered porch only count the parts inside the walls of the house.
The garage should be clean and organized, but it is not a place where you live so don't include it in the grid when doing Feng Shui of the house (the same with the deck).
Hope this helps you.
lady moon