I have set up my darkroom to do 30 x 40 inch murals in Silver and PT PD , I live work in a long narrow building and we have a fantastic basement with floor drains that lead out. to a back yard .
I have built a 30 x 40 washer and am very excited to put it to use later this summer. We have a 11 x 14 Devere which is located in the center of the darkroom and we actually cut a hole in the ceiling and the enlarger head actually can lift up into the main floor. This enlarger is very unique as its focus is controlled at the baseboard , so its a dream to focus. For this enlarger we will dedicate to only 4 x 5 and up to 11 x 14 films . We have a second Omega Condensor enlarger which we use for mural 30 x 40 and small prints due to a Baseboard that can be driven by hydraulics to variable position- this enlarger is for 35mm and medium format film. We just finished a show that required 30 x 40 inch prints and 20 x 24 inch prints from 35mm and it was a breeze.
For the PT Pd and multilayered Gum over pd prints we can go up to 30 x 40 inches as we purchased a 32 x 44 inch LED exposing unit from Cone Editions which we attached to the base vacumn frame of a 30 x 40 Nuarc plate burner.
I am very happy with this size and really see no reason to go larger as its a real PIA , quite doable but not my cup. of tea these days.
In my past life I was a mural printer at a very large mural house called Jones and Morris Murals in Toronto and I learned how to use huge horizontal Durst Enlargers to make up to 10ft by 60 ft murals in 72 inch strips.
Its much easier today to cap off a size due, to space , trays , water usage. If I have to make larger prints I use Griffin Editions in New York who do monster silver prints via enlarger or Lambda.