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Thursday, June 17, 2010

SHOP DRAWING creates maximum benefits for construction companies

The shop drawing is a drawing or collection of set of drawings, diagrams, illustrations, schedules, and other data or information specifically generated or assembled by the contractor, supplier, manufacturer, subcontractor, or fabricator to demonstrate some portion of the work for the approval of architect or engineer.

Unless this task is specifically delineated in a governing agreement, design professionals and engineers should not generate shop drawings, especially in areas relating to the means and methods of construction.

The shop drawing is a graphic or written description of the work drawn to provide the information on behalf of manufacturer or the contractor to describe the fabrication, installation of the items to the manufacturer’s production crew or contractor's installation crews. The information is shown in construction documents.

Within the steel industry a majority of fabricators and detailers prepare shop drawings for pre-fabricated components. This type of components include elevators, structural steel, trusses, pre-cast, windows, appliances, cabinets, air handling units, and millwork.

With the help of shop drawing the steel fabricator gets the ability to fabricate each piece of steel in the building. Shop drawings contain brief information relating to material specifications, sizes, dimensions, welding, bolting, surface preparation, painting requirements, etc.

In a construction project, the number of shop drawings surpasses the number of construction drawings. It is observed that approximately 70 to 80 construction drawings versus 1,000 shop drawings are required in the case of documenting the steel frame for 1,000-ton building (1,000 tons of steel).

As soon as the shop drawings are completed, the mill order can be submitted sooner, the fabrication will be started immediately and the steel can be erected sooner

Concrete reinforcing is another segment in which the shop drawing is required by reinforcing steel fabricators for fabrication of the material. Here the shop drawing is prepared to lists the quantity, sizes, lengths, and shapes of the reinforcing bar. The structural engineers review this information to make sure that sufficient reinforcing is being supplied to be organized for storage and installation.

MEP Engineers also prepare installation and coordination shop drawings for sheet metal ductwork, piping, plumbing, fire protection, and electrical. Shop drawings are not produced by architects and engineers under their contract with the owner.

In brief shop drawings can be explained as below:-
• Comparison information for the architect and engineer
• Notes of changes or alterations from the construction documents
• Information required fabricating the product
• Indication of dimensions needing verification from the jobsite
• Placement or installation information
• Samples

Now a days the drafting software(CAD), 3D steel detailing software and building information modeling software(BIM) are utilized for creation & digital review of the shop drawings in which the multiple copies of each fabricated piece drawing will be reviewed electronically eliminating the paperwork that would total approximately 30,000 sheets of drawings for a construction project.

Rajib Dey
Construction Estimating Service

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