I am looking into this myself and it seems like there is now quick solution for this... You may have looked at this topic: http://forums.odforce.net/topic/14151-roof-generator/?hl=%20straight%20%20skeleton
There is not much information about the straight skeleton:.
"Well, it's just some foreach and other sop's, some expressions, plus allot of mind bending to get them to do what it needs to be done. To be honest this thing made me think "Hey, I'm struggling to do this here in Houdini, using some nodes that are not necessarily made for this (or are they?). I should learn a little programming (Python for example). By the way, this is a pretty good example showcasing the power of Houdini (in my humble opinion at least). Maybe I'll do a tutorial some day..."
This is not much of help for me at least.
I am trying to get something to work myself. I will update you if I get it to work.
If you have come any closer getting a straight skeleton to wok, plz update me:)