Transfer of Roof Loads

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Hello. I need to do performance analysis for my final project and I need to add 65kg/m2 wood and tile load and 35 kg/m2 snow load as roof load. As I read in a previous topic, it was written that I had to directly affect the roof slab as a fixed load and a live load. Is this method correct? Or do I have to multiply by the total area and define an average load? Thanks in advance for the answers.