According to IBC, who has sole responsibility to approve materials? architect or owner?
I don't have access to IBC, so not sure where to find this. I want to say owner, cause in the end he's responsible, but the architect reviews and approves submittals. Any input on this? Or where to find this info?

Owner/architect responsibilities are not specified through building codes. They are determined according to project structure and contractual agreement:

https://network.aia.org/HigherLogic/Sys ... c820535b63