How big does the garage itself need to be?

A garage is sized by two numbers and almost everybody plans for one of them. Width is what people argue about, because it is what decides whether two cars fit side by side. Depth is what they live with, because a modern full-size pickup is close to twenty feet long on its own and a twenty-foot-deep garage with one in it has nothing behind the tailgate and nothing in front of the bumper.

The figures below are what gets built against what works. Twenty by twenty parks two cars and does nothing else; twenty-four by twenty-four is where a double garage becomes a room you can also keep things in. The gap between those two is four feet in each direction and almost the entire difference between a garage you park in and a garage you live out of.

The door is a separate decision from the building, and a smaller one than the frontage suggests: you need roughly a foot of wall at each side for the vertical track and the framing, so a twenty-foot garage takes an eighteen-foot door rather than a twenty-foot one. On anything with more than one bay there is a third decision underneath both — whether to keep the supporting piers between doors, or span the lot with one opening and pay an engineer to work out what holds the roof up. Door sizes that suit each garage →