Placing Drawings are not Shop Drawings

Requirements for early submittal can be detrimental

"Contractor will be required to have engineering such as submittals, shop drawings, and samples submitted for approval within one hundred (100) calendar days from written engineering notice to proceed."

Statements similar to this quote from the specifications for a new stadium proposed several years ago appear in many project specifications. In today's environment of ever-shortening design and construction schedules, it's understandable that specification writers feel it's necessary to impose tight time constraints on the delivery of shop drawings.

Although reinforcing bar placing drawings are often assigned to the "shop drawings" category, it's important to note that bar placing drawings are quite different from the fabrication and installation drawings required for other construction trades. In fact, the constraints placed on the production of bar placing drawings may make it impossible to comply with such a contract demand in a manner that's productive for the detailer or the contractor.


Gathering the information

There are many items on a construction project that require shop drawings, including structural steel, precast concrete, miscellaneous metal, mechanical and electrical systems, and finish items such as doors and windows. There is, however, a fundamental difference between shop drawings for most items and reinforcing bar placing drawings. Except for relatively minor embedded pieces in concrete, most items detailed in shop drawings are installed as self-contained systems or as attachments to in-place systems. In contrast, reinforcing steel is an integral part of a much larger system assembled during the concrete placing process, and proper detailing depends on how that process is carried out.

There are two reasons why many items need shop drawings prepared as quickly as possible after the project begins. Most importantly, most items are manufactured products with relatively long delivery times. They must be ordered as soon as possible to ensure that they arrive on site at the proper moment in the construction process. The second reason is that concrete cannot be placed until final concrete dimensions are determined. Although the architect and engineer prepare the initial concrete dimensions, these dimensions are fine-tuned during preparation of shop drawings for the other items, including mechanical and electrical equipment, windows and doors, and concrete formwork, required to suit the particular requirements of the project.

Rapid, early preparation of shop drawings is normally not problematic for most of these other items because they have relatively little interdependence with each other or casting concrete. For the most part, the data needed for production of these shop drawings are not dependent on the work performed by other trades.

A reinforcing bar placing drawing is, however, an entirely different matter.

First of all, reinforcing steel is fabricated and installed as part of the concrete placing process. The builder cannot begin to cast concrete until the final dimensions are known. Likewise, reinforcing bar detailers cannot complete their detailing until they have the final dimensions. Basically, detailers cannot complete their placing drawings until most of the other trades have completed their drawings.

Furthermore, they cannot complete placing drawings for many parts of the structure, especially slabs and walls, until concrete contractors have completed their formwork drawings and defined all of the relevant construction joints. In addition, there are often requestsfor- information that will have to be answered before placing drawings for the areas in question can be completed. Because of these issues, detailers are often left with very little lead time before the steel is needed. As a result, they will have to know in considerable detail the precise construction sequence so they deal with the most urgent items first. The construction sequence is also necessary so the detailer can properly arrange for necessary dowel projections from one placement into the succeeding ones.

Fortunately, there is almost always ample time for delivery of reinforcing bars, even if the placing drawings are prepared and approved only a couple of weeks before the steel is needed in the field. Because reinforcing bars are readily stockpiled and ready for almost immediate cutting and bending, production can be quite rapid. For all of these reasons, there is no compelling need to prepare placing drawings "within one hundred (100) calendar days from written engineering notice to proceed."

To complete their jobs properly, detailers must have at hand a great deal of data that often doesn't come until it becomes critical—in other words, until the lead time is gone and they are in danger of not completing their work in time for a placement. This is why the reinforcing bar detailers always seem to be behind schedule—they are the last people to get all the information they need to complete their jobs. Those that don't understand this may assume that detailers are submitting their placing drawings at the last moment due to poor planning or incompetence, but that's simply not a fair assumption.


What's best for the project?

If the reinforcing steel for a project is detailed within 100 days after notice to proceed, or simply ahead of the availability of proper data, it's almost certain that a great deal of the detailing will have to be revised. A detailer details on the basis of a unit price per ton of steel that is included in the bid price. Revising detailing is usually done at an hourly rate. The cost for redetailing in such a situation can be enormous and can be as much or more than the cost of the original detailing. This is a significant and needless cost to be passed on to the client or the client's client.

Awareness of these issues makes clear that the request for detailing to be completed far ahead of the required schedule is unreasonable. The issue at hand is to try to get all the necessary information to the reinforcing bar detailers as quickly as possible so they can keep ahead of construction. Reinforcing bar placing drawings are simply not the same as other shop drawings, and care should be taken to treat them as distinct and separate.

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