There has always been controversy about cutting the lath behind single piece vertical control joints. There is a move to revisit this language within the ASTM committee. See what others are saying about this on the WC bulletin board

ASTM C 1063 item states that "lath shall not be continuous through control joints but stopped and tied at each side. "

The issue is vertical control joints drawn by designers that fall between framing members. This happens quite a bit in the field and the Architect then forces the control to comply with ASTM. The plastering contractors has three choices.
1. Cut the lath and rely on lath attachment to the sheathing. Bad idea. I have inspected many jobs where the stucco panel,due to not being properly attached to framing, pulls and curls away from the sheathing.
2. Require the general contractor to remove the sheathing and install proper framing ( good luck with that)
3. Install the control joint over continuous lath, which has proven to work but violates ASTM C 1063.

If the language in ASTM could be changed to allow the option of continuous lath behind the vertical control joint or add language that requires the proper framing support ( not the plastering contractors responsibility) would be very helpful.

I would like the industries opinions on the matter.

Mark Fowler
Editorial Director
Wall and Ceiling Magazine