Building construction means generally the construction of sheltered enclosures with walk-in access for the purpose of housing persons, machinery, equipment, or supplies. It includes all construction of such structures, the installation of utilities and the installation of equipment, both above and below grade level as well as incidental grading, utilities and paving, unless there is an established area practice to the contrary. Additionally, such structures need not be "habitable" to be building construction. The installation of heavy machinery and/or equipment may not change the project's character as a building. Examples of building construction follow: