Preventing and mitigating rare cases of disruptive sounds from standing seam roofs.
An excerpt from Metal Construction News, August 2019, written by Christopher Brinkerhoff, Associate Editor.
Most of the time sounds from weather and movement on standing seam metal roofs are no more audible than sounds on other types of roofs, and don’t disturb people. In the rare cases when sounds are disruptive, understanding what causes them, and in what circumstances are they more and less likely to occur, can help determine how they can be anticipated, avoided and eliminated.
More specifically, standing seam roofs are different from other roof types in that, as they expand and contract with temperature changes, friction between metal components as they rub against each other can produce faint popping sounds. The sounds are typically only audible if you’re on or near the roof, or if the underside of the metal decking is exposed to finished interior space. In rare cases, in one particular roof assembly with standing seam panels, the expansion/contraction sounds can become louder inside a building. Sounds can be amplified by friction between the components in assemblies with standing seam roof panels, rigid board insulation, and metal decking.
Lisa Reimert, staff engineer at San Antonio-based Berridge Manufacturing Co., who describes the expansion/contraction noise like an empty water bottle being crinkled, says the reason sounds are sometimes amplified in the standing seam/rigid board insulation/metal decking assemblies is because the fasteners cantilever from standing seam clips through rigid board insulation to metal decking, without plywood, Z-furring or another substrate. “You create kind of a sheer or a torque on that fastener, and, in that case, that’s where you find the popping noise. The reason [plywood or Z-furring] helps mitigate the noise is because you’re not cantilevering the fastener. The noise is ultimately created by a cantilevered fastener; plain and simple.”
Another scenario in which sounds can be a factor is buildings with standing seam roofs that transition from conditioned spaces with insulation between the purlins to unconditioned spaces without insulation, for example in additions of open or enclosed storage spaces. When the standing seam clips are attached directly to framing, sometimes strong, gusting winds can build up enough pressure on the roof panels to cause noise.
Disturbance from sounds on standing seam roofs is also based on setting. In the hospital example where there is an expectation for silence, any sound, even if it’s faint, could cause disturbance. In other places, such as a factory with loud machinery or warehouse with forklifts buzzing about, soft popping noises are unlikely to cause a disturbance. “But if you’re going to have an exposed deck in an atrium situation, an atrium actually ricochets noise and it amplifies it, so that’s going to be a large issue,” Reimert says. “So it’s really just figuring out where your concern is going to be and what the room is going to be using.”