I’m looking for a non-combustible drainage plane that is noncombustible per ASTM E136. A mat would be great, since it’s behind stucco and needs a fabric to keep the plaster out of the drainage plane. Seems like all these tangled-mesh plastic products with the filter fabric have a decent flame spread (less than 50) but aren’t tested per ASTM E136. I’m trying to take advantage of the exception in IBC 2015/CBC 2016 1403.5 that allows a tall wall assembly not to need an NFPA 285 test if the air barrier is the only combustible component in the wall.
Whatcha got? Name names, please!
Perhaps you could use metal lath, installed on vertical hat channels. Galvanized or stainless steel of course.
Vivian, I highly recommend The Stucco Resource Guide from the Northwest Wall and Ceiling Bureau. It is a great reference for technical data and details for stucco.
I did find a few lath-like solutions and spacer solutions galore.
And I had one manufacturer (in keeping with my request to name names, it’s Stuc-O-Flex) point out that the drainage plane could reasonably be considered part of the air barrier, and thus be allowed to be combustible. I haven’t tried that approach yet with the code official, in the hopes of finding a true tested solution.
David, it’s a brand new exception in the code (for us in California, anyway), so since the stucco guide is $95 and I just bought its competitor for $89 from WWCCA, do you mind taking a look at it and seeing if it contains answers to my question? (The WWCCA book is not helpful on this topic, but has terrific photos of plaster textures.)
I have officially given up trying to find a non-combustible mesh drainage plane. If the owner team decides they’re comfortable calling it part of the weather barrier, I will report back how that goes.
Vivian, would something like Tyvek’s Stucco Wrap work? It is a weather barrier designed to act as a drainage plane.
“DuPont Tyvek StuccoWrap WRB has an engineered, grooved surface that is designed to be installed as a drainage plane behind stucco facades and EIFS systems.”