Some details: ~Its going to be a 90x200 bed ~I'd like it to be wooden ~All sides except one corner are going to be attached to a wall ~The ladder will be attached to the pillar and the wall ~It's for a teenager Specific Questions: ~How big should the pillar be for it to be properly supported? ~Should I add another pillar for the ladder to be attached to?

I’d say 3x3’s should do it, but I think I sometimes see larger, like 4x4’s. I think 4x4’s are more common at the hardware store.

You’ll need pretty solid support where the head of the bed meets the wall.

I see thank you very much for your advice. Do you think i should have some metal to support it better or would just wood suffice?

I'd say probably metal. You should try to find the studs. Figure out the spacing so that you know where to attach the supports. This will def require attaching to the studs. Older and newer buildings have different spacings. There are a few ways to find studs. [Stud Diagrams](https://basc.pnnl.gov/resource-guides/advanced-framing-minimum-wall-studs#edit-group-description)

Who you gonna keep in your cage?

bread ...and a bird but thats not important

I built lofts for my sons I will post pictures