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RE: Noise from screwed steel roof deck

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   Based on my life experience with high rise buildings (steel framed) with
metal decks, I found the metal decks that we used for the derrick floor
always "popped" when the sun was on it. From about 9AM until 4PM there was
constant noise from the metal decking as the suns rays (heat) traveled
across the metal deck. We would bring elevations up the building when the
Ironworkers were gone at the end of day. That top deck was constantly
popping when exposed to the sun. While in San Francisco during the summer
with the blowing cloud and fog cover there was an absence of this noise. I
have attributed the sound to the expansion of the metal due to being exposed
to changing position of the source of heat.
   When doing the Bank America building where we used temporary work floor
of wood planks there was not such noises.
   Large area roofs, such as the 40 acre Boeing 747 assembly plant in
Everett, Washington "popped" when it was exposed to the sun's rays. Even
once covered with insulation and waterproofing, there is a popping noise
when the sun's rays move across the roof. But does it ever rain. I have
attributed the sound to the expansion and contraction of the metal due to
being exposed to changing position of the source of heat.
   Go to a steel framed building under erection at the end of day and listen
to the popping of the steel as the material changes in length due to the
change in temperature and source of heat position. I have attributed the
sound to the expansion and contraction of the metal due to being exposed to
changing position of the source of heat.
   When surveying the vertical alignment of the exterior columns which are
exposed to the sun it was found that the heat of the sun's position changed
the observed alignment significantly.
   When closing the "key" in steel bridges, arches, girders, or truss spans,
the work was usually done at near mid-night so as to minimize the effect of
the sun's heat.
   Sometimes the noises emitted sound like a tension failure (the sound of a
30-06 high powered rifle).
   Sorry. The wife says I don't know when to stop.

-----Original Message-----
From: Scott Maxwell [mailto:smaxwell(--nospam--at)engin.umich.edu]
Sent: Wednesday, October 10, 2001 11:13 PM
To: seaint list server
Subject: Re: Noise from screwed steel roof deck


It is possible that the "popping" will subside once the building is
enclosed and the "climate" has stabilized.  It would seem to me that the
popping is a result of the wood shrinking/expanding due to changes in the
water content that this causes slippages at the screws.  Just my thoughts.

HTH,

Scott
Ypsilanti, MI


On Wed, 10 Oct 2001, Rick Burch wrote:

> I have a church sanctuary project under construction in which the roof
> deck is quite noisy, aparently from thermal movement.  The roof
> structure consists of a 2" steel deck supported on wood trusses at 8'
> spacings. The deck is screwed to each support with screws at 6" spacing.
> On top of the roof deck is rigid insulation with a nailable top surface
> on which asphalt shingles are nailed.
>
> The building is not yet completely closed in, so there is no HVAC
> operating yet. The roof deck makes fairly loud popping noises, which
> come from random locations and at random times, but usually about
> several seconds apart.
>
> In the original design, the architect had gyp board attached directly to
> the bottom of the steel deck. I imagine that this would have dampened
> out much or all of this noise, but unfortunately it was "value
> engineered" out when the bids came in over budget.
>
> Has anyone here had any experience with noisy steel roof decks?
> Specifically, any ideas on how to prevent this in the future (or fix
> this current problem), and also would the problem be expected to improve
> once the building is closed in and climate controlled?
>
> Thanks,
> Rick Burch
>
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