When the arrangement of the floor space of a proposed building has been decided upon, the architect prepares working drawings, or plans, for it. These plans are drawn to scale and show in minute detail and with exact dimensions each floor of the building. Exterior elevations are also shown. The plans indicate the arrangement of the plumbing, heating and lighting systems.

In some cities, a copy of the plans must be filed with the building department of the city before the work may be commenced. If the department's approval of the plans is obtained, a permit for building is issued.

Contractors are furnished with copies of the plans for the purpose of having them figure on the work and obtaining their bids. When the work has been awarded, the contractor, or the various contractors, use the plans as guides. They are required to build exactly according to the plans. It is sometimes necessary for the architect to prepare and furnish to contractors special detail drawings for the steel work, stone work, trim and other mill work, cornices, etc.

In connection with the preparation of plans, it is usual to have a diagam or survey of the lot prepared by a competent surveyor. This survey will show all that is usual on an ordinary survey, and, in addition, the location and height of adjoining buildings, the depth of the sewer below the street level, the pitch of the curb, and the location of the stakes or marks the surveyor has placed on the lot or adjoining walls.

It is often necessary to ascertain whether the walls of adjoining buildings are plumb; they frequently lean, that is, they are correct at the bottom but project at the top. A leaning wall may interfere with the erection of a steel frame building. Inquiry should be made as to the depth below the surface of the neighbor's walls. It may be necessary to support them, entailing additional expense. Local laws affecting buildings will govern as to which owner must provide the support.