deflection criteria for slate tile wall

huangyhg

deflection criteria for slate tile wall
i am working on a building with a slate tile facade.  does anyone know the appropriate deflection criteria to use for the design of curtainwalls and spandrel beams?  any help would be much appreciated.
-zach lindauer

for brittle materials, i have seen deflection limits ranging from l/480 to l/640.
thank you for your reply sperlingpe.
perhaps some additional information would be useful. slate tiles are proposed to be attached to 3/4" plywood with hooks. no grout will be used in this application. this will allow the tiles to slip in relation to one another without causing stresses within the tiles.
i believe this is very similar to a slate shingle roof, which would be designed for l/360 total load deflection. does this seem reasonable?
zfl, that is an interesting application that i've not encountered before.  slate isn't used much around here.  just curious:  are the tiles lapped similar to a roof?  what is the plywood attached to:  metal or wood studs; cmu?  unless there is industry data to the contrary and no concern about too much deflection causing leaking problems between the tiles, l/360 would be reasonable in my opinion.  
the tiles are arranged in a half-lap pattern.  the plywood is attached to metal studs.  i have not been able to find any industry data regarding this condition.  all opinions on this are very much appreciated.
-zfl
i've looked for info on the 'net, also.  nothing so far for slate used for siding.