I just let the drill cut through the interior steel sheet …and that was that for most of my interior wall attachments. Eventually I would run into a place in the interior where a wall would match up with the buses steel framing and make an attachment there.
But it’s not necessary to attach to the framing for most stuff…a good metal screw; going through the interior skin does a great job at holding things where they should be.
My exterior wooden panels were a different story …
I attached them to the bus making sure the bolts always went through a steel upright framing member with bolts ,nuts etc.
And then used a good epoxy on the nut to make sure vibrations wouldn’t loosen them.
If I was to do it again I’d use the smallest toggle-bolt dealy’s I could find for attaching the sections of wall framing that protrude out into the rig …I’m talking about up at the ceiling .
Not sure what the designated term for them is….’anchors’, maybe?
You drill out a hole that will fit them, insert it into the hole…then by a screwing action, you force the toggles to expand inside the hole. You get a very strong attachment this way.
On our bus for the main sidewall interior framing attachments …I used regular old Angle-iron attachments that I metal screwed to the steel to secure the framing.
Here’s a pic
http://www.mobilehomestead.com/newbus/n ... medet2.jpg
I did the same for the attachments that held the inside walls up.
Seems to be a very strong way to go about this because a few weeks ago I ripped out most of the interior stuff in our bus and can say it was so strongly attached I had to work really hard at getting them out.