Small house plans are normally defined as houses with less than 1800 square feet, excluding a basement. These house are also space efficient and less expensive to build on a small plot of land.
Drawing a good set of custom home plans involves integrating many different concepts and ideas into a solid and usable working plan. Many designers are able to come up with a unique or interesting preliminary design, but fail to deliver when its time to detail the house structure. They draw a pretty picture but have little or no understanding of how to translate that nice design into a working plan which the builder can understand.
The property owner can seek a variance to exceed the "building envelope," the allowable area that a home can occupy on a lot. However, the process is often lengthy and there's no guarantee that permission will be granted. Local zoning boards and community organizations often require a house be set back a certain distance from the street. Before purchasing a corner lot, find out if front-yard setback regulations apply to the lot's front and side-street boundaries. This could substantially reduce the area available for a home's footprint. Easements as well as natural features, like rock outcroppings and mature trees, may also influence where the house can be located.
Having a custom drawn designed house means a professional architect applies his skills limited to the individual homeowner's needs or what they have in mind. Factors considered in such a situation are the size of the site of construction, ideas of the individual homeowner, population around the area, and the nationally and locally existing building code plans. Time is also a considerable factor for completion of a custom designed house.