I doing a bathroom reno and would like to install a deeper tub. The tub i want to install required 45lbs/sq ft of Live load. I know that most houses are designed with an avg. of 40/sq ft and that because my tub is right beside the load bearing wall I shoulf be ok. However when I was doing some renos on the main floor I noticed that for some reason (I think because of no load bearing at the stairs) The is a 28"-30" space with no joist.I have done the calcs for a standard 2x8 SPF for 40lbs/sq ft and the max span is 12'-8" and for 50sq ft is 11'-5", but I don't know about the lager space. Does that beam make up for the space? I have attached a sketch to explain.
I have an engineer friend that can help me out but I would like some advise before I go see him.