shorten the time period necessary to design and develop project shop drawing. The most common form of a precast specification is by performance. The principal advantage of performance specifications is that it allows precaster to combine economy and optimum quality, utilizing established tooling and production techniques not envisioned by the Architect or specifier.
Performance specifications may create additional work for the architect at the design stage, because the end result must be clearly defined and several different proposals must be assessed. The accepted proposals will eventually become the standards for manufacturing. However, this additional work in the early stages is generally offset by time saved later in detailing in the architect’s office.
Performance specifications should define the scope (statement of needs) and quality of the precast concrete at an early stage. In performance specifications, the manufacturer is responsible for selecting means and methods to achieve a satisfactory result.
Properly prepared performance specifications should conform to the following criteria:
1. They should clearly state all limiting factors such as minimum or maximum thickness, depth, weight, tolerances, and any other limiting dimensions. Acceptable limits for requirements not detailed should be clearly provided. These limits may cover insulation (thermal and acoustical), interaction with other materials, services and appearance.
They should be written so that the scope is clearly defined. Items not included under the scope of the precast work must be identified and cross referenced in the Project Documents.
The architect should request samples, design and detail submissions from prospective bidders and make pre-bid approval of such submissions a prerequisite for bidding.
To the degree that such requests for pre-bid approvals form a part of the specifications, the architect should adhere to the following:
Sufficient time must be allowed for the precaster to submit samples or information for approval by the architect. Approval should be conveyed to the manufacturer in writing with sufficient time to allow completion of estimate and submittal of bid.
All proprietary pre-bid submittals should be treated in confidence and the individual producer’s original solutions or techniques protected both before and after bidding