I have a henhouse and a brooder house. They are seperated by three feet.
I have my last 6 cornish x left in the brooder house and they have access to a portion of the run i section off. When they are gone and after a good cleaning, the small enclosure I have in the run for the cornish will be removed, and all the chickens will have access to the brooder house.
The chickens will "explore" the brooder house but return to the henhouse to lay and roost.
I do have issues when I try to move my laying pullets from the brooder house to the hen house and I close the brooder house because I have a new batch of chicks. The pullets will look and search and search some more at roosting time to find a way back into the brooder house. I will have to actually catch and put some of the pullets into the henhouse at dusk, they simply refuse to go in.
I generally only have to do this two or three days and they then get the idea where to roost.
Hope this helps.