We recently purchased a quad bunk TT and like the layout. It came without any ladders to get up and down from the upper bunks. None are built in either. I know the upper bunk has a 250 lb weight limi...
We never got around to getting a ladder set up for the upper bunks. They were 6 and 8 when we got the quad bunks and they've always just shimmied up to the top on their own. It would just take up space anyway.