when does a building need to be brought up to current code

huangyhg

when does a building need to be brought up to current code?
i have been working on an addition to a warehouse.  the existing building is a rigid frame with z-purlins.  today, the client informed me that they were removing the roof from the existing building and replacing it.  does this mean i need to bring the roof framing up to current code?  under what conditions must an existing building be upgraded?
thanks
if your using ibc 2003, see chapter 34.  if what they are removing is not structural and they are replacing with like kind...no problem.  if not like kind, then as long as you don't increase the load in any member by more than 5%..no problem.  if you discover that a structural component is deficient, during the repair, that   
forgot to add....if the load in a   
thank you for the code reference twinnell.  here's a follow up question for you:
section 3403.2 states "where repairs are made to structural elements of an existing building, and uncovered structural elements are found to be unsound or otherwise structurally deficient, such elements shall be made to conform to the requrements for new structures."
what is the definition of "structurally deficient"?  i believe that this building conformed to the code that applied at the time it was built, but calculations show that the purlins and the rigid frame do not meet the current code.  does this make them "structurally deficient"?
structurally deficient in terms of the original building code.  or deficient by engineering judgment.  for example, if you see steel that is highly corroded or steel connections that appear to be grossly inadequate.  you don't have to check every   
the september 2006 issue of structure magazine had an article that will provide some additional insights.
i found this portion of the article interesting:
florida building code has a full volume that addresses existing structures. i found it to be valuable. while not complete and comprehensive, it is a start.
you may take a look at on line. it may help. here is the link to viewing it: