Since my garage is also on the property line it has no windows on that side, and the wall is cement block to meet our fire codes. My garage is attached, so anyone who got in could also enter the house, so I have a old fashion security bolt on the rear door. It's two pieces of 1.5"x3/8" steel with a hardwood 2x4 dropped across the door, and a solid wood door. They could get through the metal rollup door easier than the man door, but it's facing the street, so pretty wide open to view. The door is so heavy I had to add a roller wheel to the bottom to keep it from sagging on the hinges.