A prerequisite for a successful project
By Dean Frank, P.E., and Brian Miller
Dean Frank was previously NPCA’s Director of Industry Standards, and Brian Miller was previously an NPCA Technical Services Engineer.
Some precast concrete manufacturers shy away from architectural projects because of the potential for conflict between the architect and the manufacturer with respect to the approval of the final products. However, using samples and mock-ups can ease the process for all involved.
Before you get the job, submission of pre-bid samples (usually 12-inch-by-12-inch square) is typically required for evaluation of color and surface finish. Keep in mind that small samples generally do not reflect the day-to-day variations, surface blemishes and defects. Small samples may set an unrealistic expectation for the architect. As such, it is also a good idea to cast on multiple days to better show the day-to-day variations. Furthermore, since it is difficult to assess the unit’s appearance from small samples, additional steps may be necessary to meet the architect’s and owner’s expectations.
Once the contract is awarded and the standard samples have been accepted, plan on casting and assembling one or more full-scale mock-ups to showcase as a module or segment of the project. Use multiple pieces incorporating common project details, colors and finishes. They should be cast early in the project prior to the start of full production. For example, cast a spandrel panel, column covers, mullions and parapet sections over a couple of days to create a complete bay section of a project. Then assemble them using a temporary frame or jig, if necessary.
It’s a good idea to incorporate other trades and project materials, such as windows, sealants, flashing, masonry, etc. This way the mock-up can be used to evaluate the constructability of a design, work out issues with the other trades before going to full production, try out repairs and observe the effects of weathering.
Mock-ups should be cast using standard equipment, personnel and practices that will be used for the job. It is a good idea to cast in all inserts, plates and other embeds. This may help serve as a check for stripping and handling or storage and shipping procedures before full production starts.
Mock-ups should be used as a guide for acceptance in the yard before shipping to reduce the likelihood of expensive problems later on the job site. All mock-ups should be inspected by the architect, owner, etc., and documentation dated and signed when accepted. Be sure that the accepting authority is clearly identified in the contract documents. Do not begin full production until the workmanship, color and finish are approved. If necessary, refinish the mock-ups to produce acceptable work or remove and replace components that are not acceptable. It is extremely important to document everything. Maintain copies of all documentation and consider using photography. Accepted units will be used as the standard for acceptance of production units.
The cost of constructing a mock-up may be covered in a separate contract to establish clear job-site acceptance criteria. However, this is not always the case. If the cost is not included in the contract, you may wish to ask the architect or owner to consider it or make a smaller-scale mock-up anyway, following the same guidelines mentioned above. The expense is a small investment to help the project go smoothly.
Mock-ups may also be constructed on the job site and eventually incorporated into the building. It may be easier to coordinate with other trades when the mock-up is located at the job site, especially if there are many of them.
In the event that a mock-up is not possible or if the mock-up is constructed away from the plant at the job site, you should insist on having the architect or other approving authority inspect and approve some of the first production units. It is best if these sections remain at the plant until the end of the job to serve as a guide prior to shipping the units. Again, ensure that this approval is documented.
Using mock-ups helps open the lines of communication and understanding for all responsible parties and helps establish a project’s aesthetic expectations early in the process. Consequently, the prospect of costly and time-consuming conflicts can be reduced later on, leading to a successful project.