This is a Quest that has been on going for a few years. 3-15-13
Every time I think I have found the beginning I cross a new source or find a new wrinkle to the history.
I am anxiously awaiting a email to fill in the decade prior to where I was just a few days before.
The first panels (sandwich) with no foam go back to the thirty's. Frank Lloyd Write made one as did others others. The first SIPS were made in the thirty's to help conserve the forests.