PARAMETERS – When you are planning to build a new garage it usually requires narrowing down the options you discover in the process so you can then order garage plans suited for the lot. Your lot is already established in as particular zone regarding development. It is most likely zoned R, for residential. In your county or city jurisdiction, there is probably several R zone types having to do with lot sizes. The zones have parameters for development and building accessory structures, such as a garage. There will be limits on how close you can build to the property lines (building setbacks), height limit, height limit options based on setbacks, size limits for the square footage of space total or just footprint size.
ONE STORY GARAGES – One story garage plans are most popular because they are the least costly, take up space needed for parking and other activities, minimize visual impact on yard regarding building massive or openness to the sky – light and air. You can select preferred wall height and roof slope. The overall height must not exceed zoned height limit.
ONE STORY WITH ATTIC SPACE GARAGES – By increasing roof slope to 6 or more in 12 you create potential attic space for storage – usually crawl-around space only unless made very steep like 12 in 12. A truss profile can be designed to create a rectangular-ish open space in its center and the repetition of that truss creates a void in the roof, the attic. If the roof is of ceiling joists and rafters there is automatically a space created within the roof. The ceiling joists act as attic floor joists and should be sized to support the 20#/sf LL.
ONE STORY WITH LOFT GARAGES – By using a roof slope of 10 in 12 to 12 in 12 you create the potential for building a loft. A lot is a stand-up height attic space which has a permanent, building code compliant stairway for access/egress. Also, the floor area load would need to be 40 lbs. sq. ft. and interior height would be minimum of 7 ft. The loft can be used as habitable space by finishing it and providing HVAC (heating, ventilation, air conditioning), electrical and plumbing as applicable. Also, a certain amount of openable window space is required.
TWO STORY GARAGES – Building two full-height stories will yield the maximum floor area per allowed footprint area. One fairly common situation is that you can build full two story height if within the house building setback lines. But if you need to build closer to the property lines the height restriction kicks in and two story is not allowable. Two story garage plans are often built with a centered second-floor beam with posts carrying the second-floor joists with rim joist at wall end. The second story walls are built on the second-floor platform to support the upper roof of either trusses or rafters. Often the second floor is framed with tall I-joists making the full wall-to-wall span, eliminating the need for center beam support. This way the garage space below in unobstructed. And likewise for the second story if roof trusses are used for the clear span.