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.
In rare cases when metal roof sounds are disruptive, understanding the causes can help avoid them.
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.
Ken Buchinger, roof inspector at Houston-based MBCI and vice chairman of the Metal Construction Association’s roofing council, says, “As the panel expands and contracts, you’ve got movement, but it’s not a nice, clean, smooth movement. A certain amount of force will build up, and then either the clip top will move on the base, or the panel will move in the clip top, depending on the design. When it kind of jumps, it makes a vibration, a popping noise, like when you hear your car engine cooling off.”
The reason sounds can be amplified in the standing seam/rigid board insulation/metal decking assembly is the clips holding the standing seam roof down are fastened to the metal decking with long screws. “When that clip pops, that vibration gets transferred through that screw down to the metal deck, and that metal deck acts kind of like a drum skin; it amplifies it,” Buchinger says. “So now that little click or popping noise that you can barely hear up on the roof becomes quite loud if the metal deck is open in the building.”
Also, 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.
“The wind can create a negative pressure and it can bow a standing seam roof panel up in the middle, because unlike an R-panel or some other through-fastened panel, they’re not fastened directly to the purlins or the joists,” Buchinger says. “That wind gusting can bow that panel up real quick, and then it’ll let it go, and it can literally cause the panel to pop the top of that purlin or bar joist and make some pretty loud noises. And a lot of times you can hear that over in the conditioned part of the building.”
In addition to the noise the panels can cause in such cases, if they’re not secured, Buchinger says wind gusts can damage panels. “I have actually seen panels fracture over time from hitting those purlins over and over,” he says. “And so what I always tell erectors is glue a thermal spacer down to the top of the purlin or joist if you’re not going to put insulation down, just to deaden the noise, and also help prevent the panels from fracturing from bouncing over the years.”
Openings to Attics
In rare cases, unwanted sounds on standing seam roofs can get into buildings when attics are used as return air plenums with vent openings to the interior, creating an avenue for the noises to flow from the metal decking.
Buchinger says in one instance, at a hospital, in a space used to test children’s hearing, sounds were coming through an attic being used as a return air plenum. He says one possible strategy to muffle the noise was to install ductwork from the vents going up into the attic, and line them with insulation. Also, put insulation above the ceiling tiles and around the return air vents, even though, technically, it’s not needed. “Put a duct on it, go up, and 90 degree it a couple times, and put the fiberglass insulation inside of that duct to try to help muffle that noise before it leaks out into the room. About all you can do is seal it off.”
Similarly, Tom Diamond, PE, director of products and services at The Garland Co. Inc. in Cleveland, says, “Foam insulation can go a long way. Sometimes in an attic space if you have the insulation there, that’s great, but you can also add it to the top of the roof deck, especially if there’s a finished ceiling and you really don’t have access to an attic space.”
Overall, Buchinger says, “This is really an issue for the architects when they’re designing [a roof], but if a contractor knows it’s possible, he can warn the architect about this. But the bottom line is, if you’re designing a building that you want the inside of it quiet, and you’re using B-deck, rigid insulation and a standing seam roof, you need to seal off that attic space and not use it as a return air plenum because any noises on the roof or in the attic are going to leak right down into the building. And while I can’t guarantee that every time you do that type of roof that it’s going to do it, there’s no way to know when you’re going to run into it.”
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.”
Contractors aware of circumstances and scenarios in which disruptive sounds can crop up can be proactive in communicating about them with project team members, and complete projects in ways that make sound problems unlikely. In addition to those already mentioned, some of the things that can make standing seam roofs less likely to have sound problems are ensuring the proper quantity of standing seam clips is installed, installing the standing seam clips straight, and compensating for uneven structures.
To check a structure’s level with installed metal decking, contractors can put two-by-fours under a string line at the eave and peak, and pull string lines a few places along the length of the roof, Buchinger says. “Before you start putting a roof on a structure, it’s always a good idea to pull a string line to make sure that structural members are in alignment. If there are low spots and high spots on the deck, that can create additional issues with the clips binding more and creating more friction, and, therefore, more popping noises.”