Another item which is often missing or lacking in a set of house plans is comprehensive and accurate dimensions. We have always strived to provide more than the minimum amount of house dimensions so that it is easy for the owner and builder to layout a home on its building site. We will even calculate point to point dimensions (using trigonometry) for homes which have lots of odd angles to them (as opposed to a simple rectangle layout). Not all architects or designers will go this "extra mile," so it pays to check these things out beforehand.
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.
If you find a house plan that you love, but want to make minor changes, most companies can have their designers do that for you, at an additional fee. It is also possible to have your plans reversed, for instance, if your breakfast nook faces west but the view from the north side of your lot is more attractive, you can reverse it. Many of the sites selling house plans will allow you to see a reversed view, of houses you might want to build.
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.