A unique, curved radius metal roof wraps over and forms an exterior wall at a trendy high-end residence in Longboat Key, Fla.

Cited on a strip of land, about halfway down the Florida peninsula between the Gulf of Mexico and the Intercoastal Waterway, it took a team of skilled fabricators and installers to execute this challenging project.

Architect Jerry Sparkman, AIA, NCARB, principal, Sweets Sparkman Architecture & Interiors, Sarasota, Fla., describes the design as a “life-size sculpture with appealing geometries and artful combination of form and space.”

The white aluminum material curves around the roof and forms a wall, framing expansive views of the mangroves and bayou. The arched design provides deep overhangs which shade the day lit home from the Florida heat.

“The sweeping roofline not only creates a presence for the home, it also keeps direct sunlight from the many windows of the house through its overhang,” explains Sparkman.

The architectural standing seam metal roof’s curved design is comprised of six different radiuses ranging from 212 feet to 8 feet, with each panel measuring approximately 76 feet in length.

Located in an Exposure D category zone, just 200 yards from the ocean, not only did the metal roof need to withstand corrosion, but the building enclosure had to be engineered and tested to meet local building codes and offer protection from Florida storm and hurricane weather.

Consequently, the roofing system and selection of materials were critical for this project.

Another issue was properly attaching the roofing system. Considering the roof arch’s six radiuses, an exposed fastener system was not an option. Instead, a standing rib was needed to apply the necessary pressure to be able to stretch around the radius of the roof.

As related by Joe Keene, owner of the Vero Beach, Fla. Integrity Metals, the metal roof and panel fabricator for the project, the team considered a 1-in. mechanical standing seam panel, bet it appeared too small with the 14-inch fascia. On the other hand, 2 inches created a look that was too industrial. Consequently, the decision was made to go with a 1.5-inch panel.

In addition to delivering the needed protection, the standing seam panels creates the sleek, modern look that the owner was seeking.

As the best deterrent against saltwater, the contractor recommended aluminum. The material oxidizes as it begins to rust, thereby protecting against corrosion. The 0.032 aluminum was also easier to work with as it’s more malleable than steel.

The roof is painted with a Regal White PVDF finish. The premium paint delivers a high level of color retention, exceptional durability and protection against chalking and fading. The owner also benefits from the white finish’s cool roofing properties. In reflecting a certain percentage of the Florida sunlight, air conditioning energy consumption is lower.

Dialing in the Fabrication

For the highly unique roof comprised of six different radiuses, fabricating the barrel was quite challenging.

“Some radiuses complete a circle out of a 16-foot panel while others take 424 inches. Mathematically, being able to know exactly when the points intersected and when radiuses change was a challenge. We had to ensure the trims fell out appropriately, given that the plywood layer added an inch and changed the dimensions,” stated Keene.

Another challenge was getting the curvature right. In addition to ensuring that the calculations were precise, the bending process had to be carefully executed to ensure that its functionality was not compromised.

A portable rollformer was brought on-site. By rolling the panels in the field, the team was able to make any required adjustments on the spot.

The team also used a portable radius machine that applied pressure into the male and female rib of the panel. By supporting the sides of the leg and applying pressure, this allowed the team to achieve the desired radius.

A couple other important details included a hand-cut, two-piece gable trim matching the radius of the roof and the flashing. Regarding the former, hand rollers were used to create the kickouts and hems, and a double lock “Pittsburgh” seam on the top for a smooth, linear finish. As for the flashing, an aluminum coil was run upside down through the rollformer using the leg of the standing seam panel as Z-flashing. This innovative approach eliminated the need to manually make the trim in the shop, thereby saving time while ensuring a match with the roof’s curvature.