Hey Gary, My shelf layout is only 12" deep and will be using flats almost exclusively ( i just can't seem to get a whole building in, no matter how much I try). If it weren't for the track to the lower level (on my layout) I'd have alot more room and less headaches to try and scenic around, but I am rather surprised as to how much room 12 inches really is. BTW, I use the ready made double slot shelf brackets and am rather pleased with them. You need to fine tune level the benchwork, but they have saved me alot of work. I left the verticals long, below the layout for shelving purposes. Put some pics up when you get a chance.