What do these vertical beams in loft support?

Section62

aoleks said:

stuart45 said:

aoleks said:

As long as that steel beam was installed properly, you should be fine. Those things can take the weight of the entire roof in less than 2 meters span.

The steel purlin supports the rafters, but the hangers help the joists. Without the hangers and a binder the ceiling joists are more likely to deflect.

If there’s a beam holding the joists in place, everything else will be fine.

I'm not sure you understand what you are saying there.

If a builder has made changes to the OP's roof structure without advice from a structural engineer, then getting advice from a structural engineer should be seen as a priority, and definitely before any more of the structure is removed/replaced.

stuart45

My guess is that they had to whip out the end 2 hangers at the right of the photo to get the steel in, as they would be in the way being set back a bit.
It sounds like there is an SE involved in the work so the job should be OK in the end.
He might have calculated to be able to remove the struts once the steel was in.

stuart45

travis-powers said:

I’ve only ever worked on one loft conversion but we had to fit steels at eaves level then new joists over old however your engineer will advise.
Whoever fitted them purlins should be ashamed of themselves.

One of those purlins looks like a scaffold board.