I don't understand exactly, but I just finished a new darkroom. It is 9 x 12. The old one was about 9x9. I now have a wet and dry side, each 12 feet long. Door in the middle of the 9 foot side. My counter (dry) is a little over 36 inches deep and the sink is 36 inches deep. I never done 30" prints. I have two enlargers, both Beselers. One for 35mm and 2 and 1/4, the other for 2 and 1/ 4 up to 8x10. I like the long counter.
Sink is 3 x 8'. I'm going to add a wash sink at the end that is about 3 x 3 and a little lower.
Finishing area is outside the darkroom door. Area not complete. I am planning a 3 foot deep, 3 foot high, 11 foot long counter for mounting and matting. I don't do production, so this is big enough for me. If I need more room I will turn the corner later with an extra counter.
NIce to have the biffy nearby. I have one in the laundry room, just around the corner. Saves me running to the house.