noise from polyiso nail base panels?

Anyone ever experienced what appears to be much (and loud) thermal noise from polyiso nail base panels? We are involved in a recently-completed office bldg in St. Louis. The sloped part of the roof system is comprised of acoustical `F' deck attached via puddle welds to open web bar joists, atop which is polyiso nail base (R-30) and standing seam metal panels. There is an ice and water shield below the standing seam panels, on top of the nail base OSB. There is, however, no separation layer or vapor barrier between the metal deck and the bottom of the polyiso. The building was designed so that the top floor has a "loft" look, i.e. the roof structure is fully exposed. The noise sounds like thermal expansion, but is very loud, and widespread. Seems to be more prevalent in the morning on a sunny day or, given the current climate in St. Louis, when the heat kicks either `on' or `off'. Diagnostics to-date have included removing some of the standing seam metal panels, as it was thought the standing seam metal was the source of the noise, perhaps the clips were binding. However, after removing the metal panels the noise still persists and, as the cold weather has really set in, we also now hear much `popping' on a flat section of the roof that has solid (non acoustical) metal deck, topped with polyiso panels and a white colored TPO membrane (no metal panels). On the sloped portions of the roof, besides "popping" it sounds almost like a `tarp flopping in the breeze', rolling across the entire roof, even on calm days with no breeze. This noise (the "rolling" widespread variety) also existed in the summer when weather was warm. We are now focusing on the nail base insulation. Tentatively we are planning to remove some of the nail base panels to see how they look. The noise is so great the upper floor is untenable for professional office space. I had thought polyiso was relatively stable, inert stuff that should not be subject to thermal expansion. Almost seems like the polyiso is binding to the metal deck and then releasing itself. Any advice/history anyone can offer much appreciated.
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Any responses you receive will be interesting; we do a lot of this type roofing on schools in NJ (similar climate ), but have not yet heard noise complaints.
Tom

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Tom, thanks for the reply, it is the first one we rec'd.
I will post what we ultimately (hopefully) find out to be the cause.
At this point I suppose possibilities may include the need for a separation layer (thermal break) or vapor barrier between the metal deck and the bottom of the iso; perhaps the iso was installed too quickly after manufacture, i.e. foam not fully cured/conditioned; lack of separation (gap) between the iso panels; loss of bond between OSB and foam; improper or inconsistent fastening of the iso panels to the deck; some reason that thermal bridging is occuring down to the metal deck proper, etc.
In NJ do you ever install a vapor barrier or separation layer atop the metal deck when it is used in a situation where it is left exposed to the interior?
After this problem became apparent, time was spent going around to other buildings in the area with exposed metal deck, notably the bigger box retail structures, and similar noise was heard, to varying degrees, although in those installations (much higher ceilings, relatively noisy interior simply based on usage) it is not as problematic as for office space, where a quieter environment is needed.
In a school (gymnasium, cafeteria, etc.) for example, perhaps the noise does exist, but is not as noticeable? If this type of roof cross section were ever used in classrooms, or a library, the noise likely would be more of an issue.
Dan Wind Tom Cular wrote:

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I'd really like to see the design/erection/detail drawings for this setup. I'd also really like to hear if you reach a conclusion for the noise. I've never heard of a deal like this before. Personally I can only 'suspect' thermal expansion. On a stupid note, any chance the building itself is transferring noise from the walls to the roof? As in does the noise start on one side of the building and transfer across the roof? Radiant heating/cooling on 1 side 1st?
Dan

stable,
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James wrote:

I don't know. I can tell you this, according to the CRC Handbook of Chemistry and Physics, the only substance in which carbon is soluable is molten iron (that's how they make steel), so searching for a chemical solution is probably futile.
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I find the following extremely interesting; One reply in another group (science - acoustics) mentioned the possibility of a "stick-slip" phenomenon between the lower iso panel and metal deck interface. Maybe the interface between the two panels of iso, too?
The above I've experienced. Not after installation but during install. You can get some vicious noises by rubbing the iso over clean, dry, metal deck. And as I believe you mentioned, some serious popping noise. This possibility could be tested by applying a talc/dry lubricant or similar material between the iso and the metal deck in a test section. Heaven only knows what that would take to accomplish..........................
On a side note, we do have one section of flat roof that is "green" (vegetated atop a membrane), and I've yet to hear any large noises from that element.
This "green" somewhat validates the above "stick-slip" phenomenon. It would seem you've introduced enough added weight to increase the friction coefficient between the iso and the F deck. Hence, less movement in a given amount of time.
As an external test, use a section of F deck and a section of iso and ""drag"" the 2 pieces across each other, with different weights/surface pressure (in comparison to the real application/including roof pitch-temp & humidity) to see if you can generate the same kinds of noises you're getting from the existing roof. This could run as much as 20 lf or more with a full width sheet of F deck including the joist supports. I'd highly suspect you're going to experience some 'squealing'/shudder when the iso drags over the deck. Especially so if both are clean of dust. I'd also suspect you will generate more noise where the iso drags over the joists (or very close to) than the free space between the joists. I'd almost bet you'll get a faster repetative rate of 'shudder' over the joist with a lesser rate progressively further from the essential pinch point of the joist. Think of it like a high frequency noise transcending to a lower frequency.
From your added info to your original post, I'm still seeing a thermal problem here. I'm also seeing it as internallay generated as opposed to external. IE: The SSR But I worry about the following from you;

I just can't see the SSR transmitting the kind of noises you describe through the iso. Irrespective of that, an SSR can and will grow/shrink phenomenoly and in quick time.
Keep me informed directly if you want. This certainly has my curiosity piqued. IF at all possible, can you send a cad dwg. of the roof design? I can read any ACAD or Sketchup dwg.
Dan

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Any chance the polyiso or other panel products are maybe too tight? If there's some compression on the panel edges, maybe the panels are acting like a diaphragm, jumping from concave to convex with slight pressure/temperature changes. If you have a way to get negative or positive pressure in the building, the noise may stop. If so, I don't know what comes next, but at least you'd have something to go on.
Bill

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