What is the requirements for fire dampers in a HVAC system based on international building code?

Commercial space, 1250 square feet. HVAC system is entirely 8 and 6 inch insulated flex duct with galvanized steel diffusers. plenums, and tees. Ceilings are 10 feet high and the flex duct goes over the top of 4 walls that are steel studs and gypsum board. What, if any, are the requirements for fire dampers (how many, where at, etc.)?

Without actually seeing your office layout it is tough to say but the international code states that if a duct penetrates a fire corridor, and has an outlet on both sides of the firewall then a fire damper is required.

Note: Sheet metal duct work is rated at 1 hour so if you just penetrate the fire corridor but there is no diffuser then you will not need a fire damper as long as the duct is made of sheet metal.

This code is confusing and I have more information I have collected over the years if you want to email me.

If building is all non-combustible, fully sprinklered, most likely there is no need for fire dampers. Hopefully this system does not use above ceiling space as plenum, flex duct would not be allowed. If unit is in a mechanical room, it may need fire damper where plenum penetrates those walls...check approved plans.