Sizing of floor joists

[Saxpy]

I'm going to extend the guest house to include a bathroom and a staircase to the upper floor. It will be built on a crawl space. The problem is that there's a bit of a height restriction, so I'm trying to minimize the thickness of the floor joists.

According to the TräGuiden's dimensioning tables, which only start from 3m and up, 45x195 is the minimum dimension. My floor joist span is only 2.20 meters. What is the minimum dimension to use that still meets deflection requirements?

 

[huggan]

Assuming you will have cc 600 mm, then 45*145 C18 is sufficient or if you want something even smaller, 45*120 C30 is also possible if you have a normal floor.