12 weeks?.... you would be raising medium hens?  or heavy hens?

with this system, I presume you would still be cleaning manure out of the "brooder side" after each flock, but cleaning manure out of the other side only annually?  or ??????

I am presuming you will be washing down annually??

I have seen some single barns set up with the management scheme you describe.  However, all the farms I see with multiple barns have brooders in a separate barn.  I would think that from a disease management perspective, this would be the better way to go.  I am surprised PP is setting you up this way.  Interesting.......