FIELD NOTES / DOUBLE CURVATURE
Why Do Double-Curved Aluminum Panel Quotes Vary So Much?
Compare geometry, unique shapes, tooling, finish and installation scope on the same drawing revision.
Start with the geometry being priced
Two suppliers may quote the same gross facade area while assuming different panel divisions. One may price a smooth compound surface with individual formed panels. Another may approximate it with more joints and single curved pieces. Ask both to mark their assumed panel boundaries on the same design model. Record areas that have not been resolved rather than blending them into a unit price.
Count distinct shapes as well as parts
A schedule with 100 parts does not reveal whether there are five repeatable forming families or nearly 100 unique surfaces. The latter can add setup, tooling, model preparation and inspection time. Mold reuse is a known variable in architectural freeform panelization research. Include panel IDs, candidate family IDs and quantity in the comparison sheet. Ask the fabricator to explain how mirrored, rotated and trimmed variants were treated.
Separate material and fabrication choices
List alloy, temper, thickness and finish in each offer. Check whether the price includes forming, trimming, welded returns, polishing, reinforcement, coating and critical trial panels. A finish that must match adjacent cladding may require an approved sample and a defined acceptance process. Shipping protection and panel identification may be priced separately. Compare the same delivery destination and Incoterm.
Read the engineering exclusions
A curved skin still needs its attachment points and supporting structure coordinated. Identify who produces shop drawings, who checks wind load and deflection, and who designs brackets and the subframe. If one offer excludes these tasks, the apparent unit price is not comparable to an offer that includes them. Ask whether tooling and mock-up charges are one-time costs or embedded in the panel price.
Use a comparison table
Give every bidder the same dated model and schedule. Make columns for part count, unique form families, tooling, finish, drawing services, trial samples, packing, lead time and exclusions. Resolve deviations before deciding on price. Use the schedule checker to catch duplicate IDs and missing revision data before sending the package.