Are out in the chicken tractor, and have been off the heat lamp for about a week. Last night the temp dropped to 17 degrees (that wasn't in the forecast!!) but they did fine. These are some tough girls!
Sounds like you did a good job acclimating them! 8 week old brooder babies under light would have probably gotten sick from a 70F house to a 17F night!
Basically it's a portable pen with a little chicken house attached. Mine is not so portable since DH biult it to be 'sturdier than the one ion the plans' so I pretty much need a tractor to move it.
We almost finished our a couple of days ago. Here are pix.
We decided we want to put a door in the top at the opposite end of the shelter part. And also maybe a removable floor in the shelter part. So it's usable now, but not quite done. The dimensions of it are 2' high, 3' wide and 8' long.