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Re: Wood - replacing sill plate of bearing shear walls

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Thanks all of you for the responses. It seems that most of you would
prefer shore the wall and replace the sill plate which would be the most
appropriate method of retrofit.  However, I didn't mention that only
part of the bearing wall's sill plate (about 30% of the wall length) has
suffered water damage. By observation, the bearing wall's capacities are
still okay, will need some cleaning and chemical treatment but the
plywood is bad. The holding capacities of the nails in the sill plate
may not be good. Therefore to restore the shear capacities of the wall,
I would like to add new plate on top of existing treated & cleaned plate
with studs screwed to the existing studs. Framing anchors will be
provided at the studs to both new & old sill plates.  Nailings will be
provided at the new inside plywood sheathings and new studs, sill
plates.  Two new bolts will be added at each plate at 16" o.c.  I think
this should restore the shear capacities of the wall.

The reason I prefer not to shore the 4 story building is not to create
new cracks and excessive disturbance.  Also this wall is only 1 or 2% of
the whole system's shear resistance.



Regards

Dennis S. Wish wrote:
> 
> Another choice might be to "Sawsall" the connection of the studs to the sill
> after shorting the joists bearing on the partition. Remove the plate in
> sections. Cut out the rusted anchorbolts.  Slip in a new plate and toenail
> the studs. For additional protection you can solid block between studs and
> nail to the sill plate. Finally drill out for anchor bolts and epoxy in
> place. Allow the epoxy to work it's way up through the drilled plates to
> assure a tight fit. In most area's including Los Angeles, I have been able
> to eliminate special inspection for shear anchors in wood framed homes
> because the load per anchor (controlled by the capacity of the wood) is
> usually less than half of the capacity of the epoxy connection in shear. The
> city's generally allow you to install the epoxy without deputy inspection.
> They may not in your case because it is an apartment building. You should,
> however, be able to test 25% of the installed anchors (I think Sandy is
> probably the best one to advise you on this).
> I would recommend that you insure that any shear panels are boundary nailed
> to both the new sill plate and to the row of blocking to insure a good
> connection at the bottom (the plywood panels or metal lath nailing will help
> the connection of the block and plate in tension.
> I have used similar fixes where the contractor screwed up and slotted the
> plate rather than to drill it 1/8" over the anchor size. Crazy but true. He
> already had the roof stacked for tile and we needed to find a solution for
> the entire home. I suggested the same as I wrote above. I also requited that
> he strap across the cut-out and insure that the epoxy filled the cutout
> voids. The strap and a small strip of wood block help prevent the epoxy from
> flowing out. The strap returned the continuity in the bottom plate.
> 
> Dennis Wish PE
> 
> -----Original Message-----
> From: Tom Chiu [mailto:Tomchiu(--nospam--at)worldnet.att.net]
> Sent: Monday, June 29, 1998 7:22 PM
> To: seaoc
> Subject: Wood - replacing sill plate of bearing shear walls
> 
> Have anyone ever replaced the sill plate of an exterior bearing shear
> wall? It's a 10 years old multi-unit apartment building with water
> damage in some nonbearing and bearing wall's sill plate and rusted
> anchor bolts. I have the following options:
> 
> 1.  Temporarily shore the bearing shearwall, remove and replace the
> damaged sill plate with 3x plate and new Hilti-HSL bolts, add plywood
> sheathing at the inside face of the wall.  This option could be
> expansive.
> 
> 2.  Cut sill plate between bearing studs and install new 3x plates with
> new studs nailed to existing studs and add hilti-HSL bolts. The new
> sheathings will be nailed to the new sill plate pieces and the new
> studs.  This option seems to be cheaper and avoid temporary shoring.
> Note that there are 3 stories on top of this wall and fully occupied.
> 
> I would appreciate if anyone can provide comment, Thanks.
>
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