Scale Question

i have a simple question for you terrain gurus..... When you scratchbuild a ruined building, how tall do you all make the opening for the door and how high up is your second floor?

i tried making 2 buildings so far and one is too short and the other too big (not unusable just looks wrong when i put my figs near it), i tried using models i have to get the door scale correct but i only have dwarves, goblins and orcs. needless to say, none quite human sized and it makes my buildings look wrong. any help would be great.

thanks
Jerry

My floors are usually 2" high, with doorways ending maybe 5mm below the roofline.

i like to use 2,5" for the second floor. 2" would be the best for the proportions of the modells, but many Modells swinging something over there head or have big hats that the cant stay in 2" floors...