By Kate Gawlik, for ATAS International /
There is something aesthetically appealing about curves whether it is on a road, car or building. Curves are used in the built environment to express speed, importance, art, hospitality, intrigue, function and other design details. For those who install curved roofs, there are many points to consider. Before you embark on your next curved roofing project, review material selection, manufacturing expertise and proper installation.
Just as contractors have material options for low-slope or steep-slope roofs, they have similar options when installing curved roofs. When selecting a roofing material, ease of fabrication and installation need to be compared. Sheet metal by nature can be fabricated to accommodate twists, turns and curves. Combine these capabilities with its aesthetics, and metal quickly becomes the choice for curved roofs. However, whether you choose metal or another material, it is vital to work with your manufacturer to review specifications because there are many technical components.
Following are some for metal roofing.
Considerations for how the curved structure is built, such as framing and the deck surface, can dramatically affect the look of the finished roof. Most curved roof products themselves are not self-supporting and a deck must be used. In addition, panels that can be installed over open framing may have an improved appearance if they are installed over a solid deck.
Field verification of the roof surface is critical to ensure the built structure has been constructed according to the drawings. Dan Mester, president of Miller-Thomas Gyekis Inc., a roofing contractor in Pittsburgh, added: “It is crucial to get complete, accurate field measurements of all dimensions of the structure and make templates for the panels only after it is 100 percent built and ready for panel installation. Never assume that what is actually built will be exactly the same as shown on the architectural drawings or even specific shop drawings. Also, it is essential to have qualified installers who are experienced in curved and radius metal work to take the measurements and perform the roof installation.”
Curved roofs require careful detailing because in most cases the roof slope falls below recommended minimums at some point on the structure. Therefore, secondary waterproofing via a peel-and-stick roof membrane should be used. Dave Smith, technical service manager with ATAS International Inc., Allentown, Pa., says: “Roofing on the low-slope areas will need to be treated somewhat like a water barrier system versus what they would normally be as water shedding systems. While it is important to use proper underlayment as a precaution, there is no reason a curved metal system should not be installed as the primary weatherproofing of the roof.”
Mester noted safety and accuracy could make or break a job. “A curved roof has an even smaller margin of error, which requires a higher level of skill, experience and craftsmanship,” he said. “Additional considerations have to be made for safety, scaffolding and rigging because of the unusual shape and steep slope of a dome roof.”
Skill and craftsmanship again come into play for the perimeter flashings. Depending on the size of the radius, it may be possible to segment typical straight flashing. A more aesthetic design can be accomplished with curved flashing assemblies. Please note this will add cost, so discuss this option with the building owner and review the budget.
Beyond flashings, contractors have many other details to consider with the design team and building owners. A benefit of metal roofing is that the color, profiles, paint and substrates can be mixed and matched to create a truly custom look. When reviewing manufacturer options, look at these, as well as the manufacturing process. Yes, machinery makes it possible for contractors to curve panels onsite. But having a manufacturer factory-curve panels has many advantages.
“ATAS maintains high-end quality control in all aspects of the metal forming in its ISO-certified facility,” says Jim Bush, vice president of sales for ATAS. “Factory curving allows for the product to be delivered in crates or bundles that are easily handled at the project site versus a contractor having to bring a machine onsite and have multiple loose panels to handle in the curving process. However, some larger style roofs may have to be curved at the project site due to transportation limitations. ATAS has the ability to curve panels onsite if this condition exists so you get the best of both worlds — ATAS quality and custom curved panels.”
An indoor curve
The Sis and Herman Dupré Science Pavilion, named in honor of Mr. and Mrs. Dupré by their family and friends, is a two-story structure that sits on top of a prominent hill on the campus of Saint Vincent College in Latrobe, Pa. As the first visual when many arrive on campus, the complex was created to welcome all. A glass atrium and doorway arch marks the front of the building. Metal roofing from ATAS tops this structure.
In order to see the curved metal roof, however, you have to look inside. The designers at MacLachlan, Cornelius & Filoni Inc., Pittsburgh, created an indoor planetarium within the $39 million science complex.
“The dome of the planetarium is essential for functional purposes of astrology, but it isn’t every day that ATAS gets a spec to create a metal roof for an indoor application,” Bush said. “The outside of the building is welcoming, but discovering the planetarium just beyond the glass atrium invites additional exploration and learning.”
The roof of the Angelo Taiani Planetarium and Astronaut Exhibit is PC Snap-On System (PCP999), 0.040-inch aluminum in Champagne color. Miller-Thomas Gyekis installed it and the distributor was North Coast Commercial Roofing Systems Inc., Pittsburgh. The PC system, designed for tapered and curved installations, consists of the flat panel and a separate standing seam. The seam is snapped over the clips concealing the fastening system. The PC systems are not structural panels and must be applied to a solid substrate.
Some might think the interior dome provided fewer challenges than an exterior installation, but it actually presented with a few unique requirements. Mester noted that his crew gave this project a tremendous amount of extra care and attention because any minor flaw or imperfection would be easily noticed. The roof, after all, is highly visible from the inside.
The planetarium allows the astrology professors at Saint Vincent College to project the nighttime sky and views from any point in space. In all, the planetarium’s projector displays about 20 million stars and 1 million galaxies. It does this with a Spitz SciDome full-dome projector broadcasting images on the 24-foot dome. The system has an astounding resolution of 1.5 million pixels that draws students and visitors to campus events.
None of this would be possible without the dome of the planetarium, proving that curved roofing applications have both form and function with the added benefit of beauty and intrigue. Properly prepare for your next curved roofing project, and you could get results like this.
Kate Gawlik is a marketing consultant with ATAS International Inc., Allentown, Pa. She is based in Woodridge, Ill.