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.
- posted
17 years ago