Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Plywood Shear Walls

[Subject Prev][Subject Next][Thread Prev][Thread Next]
I have been providing construction support for the seismic upgrade of a wood
building in Orange County. My responsibility for this project is to provide
the contractor with revisions to the contract details when it is determined
that the existing structural conditions are different than the ones we
assumed in our design. The client has a construction inspector on staff who
has been present during the construction to assure that the work is
proceeding according to our plans.

Part of the work involves opening up existing plywood shear walls and adding
new, or replacing existing holdowns. The inspector has been taking
photographs to document the work being done and has provided us with a copy
of the photos. I have had a high level of confidence in both the contractor
and the inspector based on my observations of the work and conversations
with them. However, I noticed one, and possibly several problems recorded in
the photographs which I need to make sure are resolved. One problem has to
do with the edge nailing of the plywood replaced after the installation of
holdowns. The contractor cut the existing plywood above the sill plate and
apparantly did not block and and nail the plywood edges at that location.
The walls have all been finished with gypboard and painted. I am going to
have the contractor remove the finish at the ends of several shear walls to
verify that the plywood edges have been blocked and nailed.  

A second concern I have is the width of the plywood used to replace existing
plywood at holdown locations, as well as the width of remaining plywood
panels after the removal of a piece for access to the holdowns. It is
obvious from the photographs that the widths of the plywood replacement
pieces are less than 24". Our plans, and revised details provided for the
contractor, clearly show a 24" minimum width for plywood panels, whether the
plywood is new or existing. Upon reading Section 2314.5.3 of the 1994 UBC, I
found that the code does not limit the width of plywood for diaphragms as
long as all the edges are blocked and nailed. Have I correctly interpreted
the intent of the code? Also, whether or not the code allows it, is there a
good reason to limit the width of plywood panels if the edges are all
nailed?