Using R6 Zip System Sheathing in Lieu of 1/2" plywood roof diaphragm

[Respawn]

Has anyone substituted a roof diaphragm design with zip system (insulation side down)? I am being asked to see if R6 zip will work. Doing some research I only found that there are shear capacities for a shearwall application. Would this work in a seismic design category D? Looking for references to getting diaphragm capacity, etc.. It appears span wise it follows APA span ratings.

 

[phamENG]

Can't say for certain, but I would say no. The shear wall capacities are questionable, and the stiffness is terrible. Instead of nails in shear, you have nails in bending through that insulation. Very inefficient structurally. I'd be shocked if that were allowed in SDC D.

 

[skeletron]

I only see this ZIP system used by the framer-influencers on Instagram, some of whom are in the PNW (SDC?). Not sure if this goes under the radar by way of prescriptive design, an engineer with incredibly sharp pencil, or an internet anomaly.

 

[jerseyshore]

Used and seen lots of zip on walls around here, especially since the last code update. But wouldn't trust it as diaphragm. You can reach out to them but as pham said it's not a great product from a structural perspective to begin with.

 

[phamENG]

I imagine I'll have to start battling it more now, but I'll offer up the exterior rigid insulation as an alternative. That way they can get their insulation, and I can have an efficient LFRS.

 

[GaStruct]

I had this battle a year or so ago with a client wanting to use the 2.5" panel for the walls. The shear values weren't even close to working. I contacted Huber and they acknowledged this common issue and didn't have much to say except they recommended sheathing the walls with 1/2" OSB/Ply first and then installing Zip R over it. Exterior rigid would be cheaper.

Not sure how anyone gets it to work with such small shear values for the larger panels.

 

[Respawn]

Thank you for the replies. I ended up suggesting installing rigid insulation or the zip system on top of the plywood sheathing.

 

[XR250]

I imagine I'll have to start battling it more now, but I'll offer up the exterior rigid insulation as an alternative. That way they can get their insulation, and I can have an efficient LFRS.

In heavy shear areas, I sheath in osb first and then go down an "R" on the Zip so everything flushes out.
I hate this stuff although I did use R3 on my house as i figure 1/2" nail cantilever is OK and my shear demand is low.