Assieh,
You can probably make this object using a combination of techniques.
There seem to be four elements composing the object.
The first element is the grate floor of the landings which can be made
with narrow slabs multiplied.
The second element is the railings which can be made using TrussMaker.
The third element is the steep stairs that can be made by using
slabs for the treads and and roofs for the stringers or use the ships ladder
and the handrails can be made with TrussMaker.
The fourth element is the vertical pull-down ladder to the street which
can be made with TrussMaker.
After you have made one assembly for one floor with one set of steps
going up to the next landing save the whole assembly (except the
pull-down ladder) as a library part.
Then you can stack these units vertically for each floor of your building.
These fire escapes come in a few standard sizes do they not ?
Therefor, going through the effort might be worth it.
Peter Devlin