80....... 4ft -300 lb cast stones  24inches across ...nice big stuff
architect wants it to go down in mud on a flat parapet brick wall on a historic building
I said fine
He then said he  wants them anchored   I said they  were never anchored as they worked in compression
He said anchor them
I said fine

He said to lay the stones down in mortar ;but meanwhile he has the roofer  to lay down  plastic -fire and ice sheild flashing- all the way  tru and across the setting substrate ,
anchor I can do ...... .
......but the -fire and ice sheild - I don't feel so fine about in a bed of mortar
why mud it ? when I am going to have a cold joint ?
Yes It needs a bed ,and yes it needs to adhere but mortar and sand  aren't going to do much on a plastic substrate  So be grateful the stupid architect is willing to put the anchors in, set them before the membrane goes in (or drill thru the membrane, set the anchors in epoxy, and then put down the mortar bed and the precast with horiz pins thru the head joints and the eyes in the anchors.   Maybe you can convince the genius architect  to let you use asphalt-coated copper flashing so there's a CHANCE of some bonding between mortar and flashing.   But you knew all this.