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RE: Backing Requirements for Lath ?

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The cheapest way would be to convince the inspector that nailing to the wood panels is acceptable.  You’ll be nailing to the platform framing immediately adjacent to the strap, and to the studs above and below the straps, so the affected area is rather small in the grand scheme of things.


If that doesn’t work, and if you still have access to the wall from the interior, one solution would be to scab on an additional short piece of 2x4 to the side each stud beside the strap.  The lath can be stapled to this extra stud instead of the main stud.



Jason Kilgore

Leigh & O'Kane, LLC

Kansas City, Missouri

From: Bill Allen, S.E. [mailto:T.W.Allen(--nospam--at)]
Sent: Friday, August 13, 2004 10:28 AM
To: seaint(--nospam--at)
Subject: Backing Requirements for Lath ?


I have a condition where I have attached a parapet to a platform framed wall. The parapet is laterally braced by a kicker back to the roof. I have a 1-1/4” wide x 16 gage strap (Simpson CS16) connecting the vertical face of the parapet to the studs below (a strap at each stud at 16”). Because of the end length of the strap on each end plus the depth of framing, the strap is about four feet long. The wall and the parapet face are sheathed in plywood.


The inspector claims that, when they install the lath for the stucco, the staples can’t penetrate the strap (which I agree) and therefore the lath won’t be connected to the framing.


Design conditions: 1997 UBC/2001 CBC; 100 mph wind, 6.4 km from the San Andreas fault (just in case any of that is pertinent to the question).


The question:

Is it mandatory that the staples go into framing members at 16” or is stapling to the plywood adequate? If one cannot staple into plywood sheathing (oops, I mean Wood Structural Panels, sorry APA), are there other methods of attachment (screws, etc.) which would be satisfactory into WSPs? If so (or if not), are there any good references related to the installation of metal lath? Usually, my design interests stop at the sheathing. The architect on the project is looking into this and I believe all involved would rather not have a structural solution (straps are already in, plywood installed, etc.).


I’ve specified straps before and I have never had this question come up. We (the contractor, the architect and I) have a good working relationship, so this is not a finger pointing exercise. We are just looking for a practical solution to the problem. The preferable solution is to tell the inspector to pound sand, but politely of course :o).




T. William (Bill) Allen, S.E. (CA #2607)


Consulting Structural Engineers

V (949) 248-8588

F (949) 209-2509