# Eapansion Joints in Stucco Walls



## conarb (Apr 16, 2010)

The 2007 CBC says this for exterior walls in a Wildlands-Urban Interface Zone:





> 704A.3.1 General. Exterior walls shall be approvednoncombustible or ignition-resistant material,.......


A stucco wall is rated at one hour; however, ASTM C1063 requires expansion joints at panels no larger than 144 square feet with no dimension more than 12 square feet (I know lots of contractors cheat on this, I've seen cheap tract homes without any expansion joints).My question is what about the integrity of the 1 hour wall at the expansion joints?  It appears to me that fire could enter through the joints.  http://dickseibert.com/metallath.pdf  Does anyone make fireproof stucco accessories? I could cover the entire building with DensGlass, but that seems rather expensive to protect only the expansion joints.http://www.ebuild.com/product-detail/structural-products--systems/182311.hwx


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## Mule (Apr 16, 2010)

Isn't the stucco just a part of the 1 hour wall. Isn't there other components other than stucco? On another thought. Isn't there a provision for so many/much penetrations in a wall? you would need to caulk the joints, per the attachment, could that be fire caulk?

Just a few of my thoughts.


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## brudgers (Apr 16, 2010)

Cement plaster requires _control joints_ @ 144 sf, not expansion joints.

Typically, control joints are galvanized steel or PVC.

Typically, both materials would be considered "ignition resistant" at worst.


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## conarb (Apr 16, 2010)

\ said:
			
		

> Typically, both materials would be considered "ignition resistant" at  worst.


Thanks Brudgers, that answers my question.


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