This is my actual darkroom. It is simple and small, and it is perfect for printing as big as 12x16 FB papers. However it is possible to print 16x20 if it is necessary.
The enlarger is a Durst M805, condenser one, mounted directly to the wall and working with my Analyzer Pro from RH Designs. The wood sink (1.75 m x 0.65 m x 0.20 m) has a lot of special resin layers and it has been reinforced with fibber glass. I also have the 12x16 Nova Washmaster-ECO Archival Print Washer and I put it on a metal support above the sink, just at the right hand.
The darkroom has a ventilation system. I used a vent that can move more than twenty times per hour the total volume of the darkroom (Just in case, this is the vent I bought: Soler & Palau TD-350/125 SILENT). The air is exhausted trough plastic pipes directly to the backyard. I also bought a 12x12 Doran Heavy Duty Darkroom Light Tight Louvers in Adorama, and I put it at the door.
I hope this information could be helpful to people that have small rooms available to become darkrooms.