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[SEAOC] Re: [SEAOC] Plywood over spaced sheathing

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>".....  The owners have reported hearing "loud popping sounds". 
>
>..."I believe the temperature of the attic may be the culprit.  There are
only a
>few attic vents in the stucco soffits."

If this is a manufactured truss, did you look at the intersection of the
sheetrock (if used) between the top of the walls and the ceiling?  In some
areas with improper ventilation, manufacturered trusses have a habbit of
bowing upward and pulling away from the top of the walls.  Also, if the
moisture content of the members gets very low - like 6% or less, the wood
members shrink in size and cause other problems.  Refer to grading rules for
volume change per difference in moisture content and then measure the
members.  We have found that member sizes no longer conform to minimum UBC
sizes when the moisture content is very low.

Reference material:

"Ceiling-Floor Partition Separation:  What Is It and Why Is It Occurring?"
Donald H. Percival, Small Homes Council-Building Research Council
University of Illinois at Urbana-Champaign, Tech Note 18.

Page 69, Item 16:  Seasonal truss uplift..... ect.
ASCE Journal of Perfomance of Constructed Facilities/May/1996



Neil Moore
S.E.

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