Rationale

During the September 2024 SWG meeting, it was explained that the horizontal thickness requirements for three-coat work over lath was originally developed and intended for open stud framing construction. The horizontal thickness requirements for lath over sheathed construction were intended to be the same as that for lath over solid base. However, as written, Table 4 does not properly capture this intention. This has led to confusion as to why the thickness requirements are different for lath over sheathing and lath over solid base when they should not be. The proposed changes articulate the intended horizontal thickness requirements by setting the requirements as ¼", ¼", 1/8" and 5/8" for the first coat, second coat, third coat, and total thickness, respectively, for lath over open framing and ½", ¼", 1/8", and 7/8" for the first coat, second coat, third coat, and total thickness, respectively, for lath over sheathed construction and for lath over solid base applications.