This bed requires a minimum length of 150" For Twins to be end-to-end or 160" for Twin XL to be end to end. Extending past 150" allows for a more roomier feel as the two top mattresses don't have to touch end to end. For example, with rooms that are wider than 150" allow a platform to be between the two mattresses, making it easier after climbing up to the loft to transition to either side.
The bed shown below is a queen, and would have about 36" on each side from ladder to bed to ladder. A king would allow for a minimum of 28" on either side.
This type of triple bunk is ideal for ceilings that are standard in height and is much more comfortable for people sleeping down below and up top!
This bed requires a minimum of 150" for two twins or two full mattresses up top, for queen mattresses up top it would require a minimum wall length of 160". The length of the queen below is 84" from the wall.
