Hello everyone. Keith,I finally made it here .... LOL
Although I'm new here on this forum, I've been making signs for years & can probably answer most questions about dimensional signs. I use about 25 sheets of Corafoam HDU every year, & I warranty my work, so I'm pretty much in tune with what you should & shouldn't do with HDU. I still use cedar, cypress & redwood as well.
Some of you may recognize the last name from other forums ... "T.R" & me are the same guy.
Here's a pic of some of my work. This one is in vertical grain Western Redcedar, sandblasted, & painted with Porter & MF Acrylic paints.