CC dimensions for stable outdoor floor?

[elpaco]

Grateful for opinions.

I have built an outdoor storage and due to the supplier's mishap, I have extra roof trusses 45x170 C30 (wrong delivery). I thought of using these as the floor, and want to frame underneath with treated lumber. The storage floor will measure 325 x 275 cm2.

Question: Suitable cc and dimension for the joists? Spontaneously feels like a bit of overkill with cc60...

 

[HogeN]

40cc

 

[elpaco]

40cc

Can you consider elaborating a bit.. Do you think I should have closer spacing with 45mm construction-grade timber than with 22mm decking?

 

[elpaco]

No one else with an opinion?