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Posted by Dan Deckert on December 13, 2006, 1:12 am
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;
> On a sunny day, whether it be very cold or very warm outside, normally
> about 9 a.m. the noise starts up over the entire roof, is not
> localized. If a cloud passes over the sun, the noise diminishes, goes
> away. When the cloud leaves the path of the sun, noise immediately
> starts back up. Sounds include both popping and what I would term as
> "flutter" across large sections of the roof.
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
> Dan,
>
> The building walls are a combination of concrete-filled masonry block
> and std stick frame walls. Roof is open web bar joists spanning WF
> beams, with acoustical decking. The standing seam portion of the roof
> has two layers of insulation: 2 inches of polyiso topped with 3 inches
> of nailbase iso.
>
> On a sunny day, whether it be very cold or very warm outside, normally
> about 9 a.m. the noise starts up over the entire roof, is not
> localized. If a cloud passes over the sun, the noise diminishes, goes
> away. When the cloud leaves the path of the sun, noise immediately
> starts back up. Sounds include both popping and what I would term as
> "flutter" across large sections of the roof.
>
> A few weeks ago we had a few days of weather here where it was almost
> a constant 60 degree temp, very little fluctuation all day long. During
> this stretch I noticed the noises were much less, which seemed to
> indicate it must be thermal, as whatever material is making the noise
> must have reached a certain elongated state, and effectively stayed
> there. When the sun came out in the morining, the noises were less, if
> any.
>
> Given those attributes we thought it was the metal standing seam but,
> after the panels were pulled from a large section, exposing the
> ice/water shield atop the nailbase, the noise still persists, albeit to
> a (seemingly) somewhat lesser degree. (I now wonder if the black ice
> and water shield may be part of the noise). Plus, we are now getting
> much "popping" in a flat section of the roof that also has polyiso, but
> is topped with a white TPO. Did not hear that section make much racket
> this summer; it has seemed to become more prevalent in the winter, when
> the heat kicks on. This lead me back to the polyiso. I've heard about
> thermal `drift' in iso, which as I understand things has to do with
> reduction in R values over time, but I wonder if the chemcial-physical
> changes that contribute to such `drift' may also be tied to the noise
> issue.
>
> 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?
>
> 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.
>
> Only thing it seems like we can do is to selectively remove sections of
> the roof, isolating parts to a point where we do not have the noise.
> National Roofing Contractors Association is also in contact, trying to
> offer up some ideas as well.
>
> Once we get to a point of resolution I will post what we find out the
> problem to be, hoping and assuming we get there. But, until then, I
> appreciate all the various ideas and suggestions. Whatever is taking
> palce here I do not wish on anyone, so as a "case study" this should
> end up being a Notice to Industry of things to watch out for.
>
>
> Dan Deckert wrote:
> > 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
> >
> > > 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:
> > > > 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
> > > >
> > > >
> > > > > 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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