Reproducible Set - You can buy a reproducible set if you think you may need minor changes made to your home plans. You can make copies from this type of home plan, but you are not allowed to build more than one home from these type of plans without a separate license.
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.
Remember that plans are not necessarily "as is." Builders can use a reverse set of plans (sometimes called a mirror image) to better site a house. It's also possible to hire an architect or modification service to personalize a plan. Ask if reproducible prints or electronic CADD files are available for the selected plan. Either will make the alteration process quicker and easier.
In addition, good stock plans come with a detailed inventory, which you can use while you're developing out your dream house. This is important for two reasons: you can look at the materials used to build your house and determine whether your budget will stretch to accommodate them, and you can get a very good idea of where to upgrade and downgrade materials.