I understand plaster board such as blue board is used when plastering walls instead of traditional taping/mudding of the seams, but can you plaster on fire rated drywall. I currently have the fire rated drywall in my garage due to code and am looking at just having my garage plastered.

Let me correct you you have 5/8 fire rated sheetrock white board in your garage it would be better use drywall products over that rather than plaster because plaster is used on blue board which is a bit different than sheetrock blue board is made to suck the moisture out of the plaster that is put on it plus plaster uses mesh tape which is not as strong as drywall paper tape with drywall you can have it sanded smooth or you can texture it the same as plaster

Thank you. Yes it is 5/8 fire rated sheetrock. Didn't realize what I originally typed.