Cubic feet is not normally the relevant issue -- chickens basically just inhabig two-dimensional space, so it is SQUARE feet you need to consider.
You will get various opinions, ranging from commercial chickens being given 1.5-2 sq ft per chicken (total), to people in very mild climates using 2 sq ft per chicken indoors plus at least 8-10 sq ft per chicken in the run, to 4 sq ft per chicken indoors plus at least 8-10 per chicken in the run, to much larger than that.
I am in the 'much larger than that' camp. Having tried keeping chickens at 4-6 sq ft per chicken indoors plus ample run, and at 10-15 sq ft per chicken indoors plus ample run, I would never go back to the smaller space.
It does depend a fair bit on climate, though -- if you live somewhere that never has weather that makes the chickens want to spend lots of time indoors, tighter indoor quarters are less likely to be a big deal, provided you have lots of outdoors for them to use.
For 45 chickens at, let's say, 3 ft per hen (which is rather crowded if they ever want to mostly stay in...) you would be building something like a 12x12 coop and something like a 12x36 run... MINIMUM.
Giving them more than the minimum is a pretty good idea, though, as it will mean less stress, less likelihood of bad problems like picking and cannibalism, and much easier management chores for you.
Good luck, have fun,
Pat