advice needed .

hallo everybody .happy new year and best wishes !
it is geting cold in greece its around 0 celcius at night
my mandarins and wood ducks seem to enjoy the cold. i am curently finishing my chicken house am geting 4 brahma chicks (i rooster 3 hens)in around two months, i have a 3,5x 2,5 m well protected area as their run conected to a nest area 1,5m x 75 x 1m is bulit by bricks . today i bulted them a wooden dust bath ( size 70cm x 70 cm x 25 cm will lay it with 10-15 cm of fine sand) and two wooden nest boxes (size 45cm x 52cm x 45 cm) that i will place one on top of the other and lay them with wood shavings and use dry dwarf papyrus to form the ring where the hens will lay (i do the same for my pheasants and the eggs stay centered and dont roll around under the hens).
i need some advice about my chicken house work for tomorow. i would be very gratefull if anybody can give me some advice on the following matters:
1 the opening that conects the run to the nests is 25cm wide x 34cm tall . can a large brahma fit through an opening like that? it is built by cement and it is nicely decorated but i made so i can unmake and remake it if needed
2 i need to make roosts for the birds but i finding out that brahmas cant fly very high can anybody tell me how high i need to make the roosts?
will post photos when everything is painted and in place.
thank u all in advance

 

thank u all for you mesages .i am glad i will not have to destroy the cement and brick door after i painted the wall. i know about the litle laders i use one for a nest box because one of my pairs of ducks is wing cliped . i will buit one for the top chicken nest box too because i am not sure how easy it will be for a hen to jump 50cm posibly on a nest full of eggs in the future. i keep searching about brahmas on the net and it seems the cant jump over 3 feet fences so i guess their roosts have to be lower than 3 feet .

 

i have pictures of my new chicken house how can i post them?