(and yes i already know the minimum is 5 sq ft per bird).
It is actually 4 square feet per bird,,,,, but that is only a suggested guideline. Depending on the size of your chickens, you numbers may vary.
A very important size,,, is also the overall volume of your coop. I strongly suggest making any coop... a walkin height. Here are some advantages listed.
Easier to clean.
Better, and easier to ventilate. Both hot, and cold weather.
More room for chickens since you can have more than one roost level.
More volume give more air to be fresh, rather than small volume that would get stuffy easier. I'm referring to ammonia and humidity which is a product of chicken poop.
Easier to provide ambient daylight to interior.
I could think of more if I keep going.
Consider what you are going to build,, as an addition. this way your coop just becomes multi room type, with connecting doorways. ( The construction portion calls for 3 walls, rather than 4.). This also has advantages when you need to introduce new chickens to existing flock. Easier to partition then.
Post pix of what you currently have,,, with details of numbers, and types of chickens.
Hope I shined some light here as a start.
WISHING YOU BEST,,,,,,,,,,,,,,,,,,,,,,,and
