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URM - Parapet Bracing Question -Reply

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Dennis,

My copy of 1994 UCBC Appendix 1 does not have the 10 foot rule for
parapets. Anchors are generally limited to 6 feet but this could be strictly
interpreted to mean only the diaphragm anchorage as written. The actual
language is given below. By the way, I get these quick code quotes off
my ICBO CODE EXPRESS CD  I think this is a great tool for quickly finding
code requirements from all of the uniform codes. Here's the section: 

 A113.6 Parapets. Parapets and exterior wall appendages not
conforming to this chapter shall be removed, or stabilized or braced to
ensure that the parapets and appendages remain in their original position.
The maximum height of an unbraced unreinforced masonry parapet
above the lower of either the level of tension anchors or roof sheathing
shall not exceed the height-to-thickness ratio shown in Table A-1-F. If
the required parapet height exceeds this maximum height, a bracing
system designed for the forces determined in accordance with Chapter
16 of the Building Code shall support the top of the parapet. Parapet
corrective work must be performed in conjunction with the installation of
tension roof anchors. The minimum height of a parapet above any wall
anchor shall be 12 inches (305 mm). 
EXCEPTION: If a reinforced concrete beam is provided at the top of the
wall, the minimum height above the wall anchor may be 6 inches .

Literally, this means its up to the design but I have seen most URM
parapet braces spaced at six feet.

Hop this helps,

Tim McCormick, P.E.
City of Los Angeles