Many of FM's design criteria are more strict than the governing building codes. This seems to be especially true for roofing components. We have binders and binders full of FM data. It's a pain in the neck, really. You think you have it licked using ASCE, ACI, AISC, NFPA, and the governing model building code, then you need to comb through FM as well to see if it will govern.
What you need to do is talk to your client to find out if their facility must follow FM guidelines. We have some large clients who refuse to do certain things FM "requires" and simply negotiate their insurance rates accordingly.
IRI is another agency fimilar to FM but with a less extensive repertoire of requirements.