TABLE OF CONTENTS Contract and Mechanical Drawings. When construction of a new building or alteration in an existing building is contemplated, the owner usually contracts for the professional services of architects and engineers. To satisfy the owner's purpose, his requirements, and his budget limitations for the work to be done, these architects and engineers will prepare design drawings and work specifications for the project. The drawings and specifications are of four major categories mechanical, structural, electrical, and architectural. The drawings are generally drawn to scales of 1/8 ?=1'-0 ? or 1/4 ?=1 ?-0 ?, and this scale is noted on the drawing. Estimates are prepared from these drawings by various contractors, who will then submit bids for their phase of the installation. Bids are selected by the architect or engineer, and contracts signed on the basis of the design drawings, which are then identified as the contract drawings. Subsequent revisions to the contract drawings may involve additional costs or credits to the owner. The sheetmetal draftsman should check drawing number, scale, date, revision number (if any), orientation, and general notes of each design drawing used for reference while preparing shop drawings.
Basically, the mechanical drawings are schematic and intended to show general arrangements of equipment, sizes of ducts, piping, and wiring layouts. However, it is not uncommon for these drawings to locate ducts, pipes, or equipment by definite dimensions. If a draftsman is unable to achieve...
