average garage cost
1 According to author Stu Silverman the average cost of adding a garage begins at roughly $7,500, and for a two-car garage the average costs will go much higher.2  This sort of structure will average at $27,040. 3  The resale value of this update would hold at $21,635, or a nearly 81% return on investment. According to author Stu Silverman the average cost of adding a garage begins at roughly $7,500, and for a two-car garage the average costs will go much higher.