Mr. Mackey's house is built just like every other house in South Park. The house is colored a red-brownish color. He has three connected mailboxes outside, odd since most other houses in South Park don't have one. His garden has a Hot Tub on the decking.
Mr. Mackey's house has a front room on the first floor large enough to host parties in. On the second floor his bedroom and presumably a bathroom exist. His basement is also shown, there's likely more than one room as the one shown has a door leading into it rather than stairs.