The Devil is in the Details
By Amy Stokes
More than any other roof system, standing-seam metal requires unique details to maintain its structural integrity and provide a lifetime of watertight protection.
Experienced metal roofing contractors know that a roof system which is properly detailed by the manufacturer will not only perform as designed, but can significantly reduce labor costs and protect both the installer and designer from potential liability.
Manufacturer-Supplied Details
Properly engineered and installed details are absolutely crucial to metal roof system performance. While most roofing system manufacturers do offer standard boiler-plate details to designers, it is imperative to provide customized details engineered for each project, as well as thorough step-by-step installation guidelines. It's simply not realistic to expect the installer's roofing crew to understand thermal expansion coefficients, modulus of elasticity, and internal strain forces.
A comprehensive shop drawing package prepared by the manufacturer is the most effective way to ensure optimum product performance and proper installation, and to reduce potential liability for design professionals, installers and building owners.
Any standing seam roof can include a wide variety installation conditions, as well as a wide variety of detailing methods to address them. To help you understand how specific details affect overall system performance, let's take a closer look at an example - the Series 300 Expanding Eave.
To Cleat or Not To Cleat
Some metal roofing professionals believe that a hemmed cleat is required at the eave to inhibit water infiltration. However, a cleat can inhibit the natural expansion and contraction of metal if there is not enough room left for movement. Proper cleat positioning is necessary for maintaining adequate clearances to allow the natural expansion and contraction of the metal.
Requiring a cleat, and its proper placement, leaves the responsibility for system performance completely with the contractor, rather than with the manufacturer. It requires the installer to fully understand the ambient temperature on the day of installation. If panels are installed on a 100-degree hot August day, the installer must leave enough room for "shrinkage" so that when temperatures drop in cold winter months, the system can accommodate the panel contraction without failure.
Expanding Eave
A properly engineered Expanding Eave, on the other hand, provides total watertight protection while allowing unlimited thermal movement.
IMETCO's Series 300 expanding eave, for example, allows panels to "float" as needed to accommodate their natural movement. It also provides three lines of defense against water infiltration:
- An edge stiffener
- Eave foam with butyl sealant, and
- An eave return
Take a closer look at the Series 300 Expanding Eave:
- Download a side-by-side comparison of the Expanding Eave vs. a hemmed cleat.
- Download an CAD detail (.dwg) of the Series 300 Expanding Eave
- Download a PDF of the Series 300 Expanding Eave detail
To request information about additional Series 300 details, or to schedule an accredited on-site presentation, click here to contact your IMETCO representative.
Be sure to ask about all of IMETCO's high-performance metal roofing, metal wall panels, and metal edge (fascia and coping) systems.
