large Panels

Hi All,

I have to manufacture some large panels for signage. Panels are about 10 feet wide x 8 feet high x 1.5” thick.
Western Red cedar VG, laminated using approximately 1.75” continuous sections. The architect has specked an end strip about 2” wide running vertically up the sides to hide the end grain. (perpendicular to the grain of the main panel.) He has specked it to be glued and screwed every 8” on center. I was thinking that expansion on this panel could total up to about 3/4” – 1”. Am I way off on this assumption? I have not worked much with WRC VG especially on a panel this size. I was thinking of offering a breadboard design to these ends. These panels will be manufactured and installed in the Northeast US. Mounting will be to 3 steel 4×4 using keyhole bracketry. Stained finish. I was wondering if I could get some opinions on this.

Issue number 2:
2 panels will be mounted to one set of steel 4×4 posts (3 total posts) on opposite sides. The space between the panels (where the posts are) will be enclosed with more cedar. Only one surface of each panel will be exposed to sunlight while the other side will be forever hidden. The 6 keyhole brackets will be all that is supporting each panel. I feel that the there may be more support needed in the field of the panel to resist any cupping due to the sunlight constantly hitting the face.

Thanks for any help on this…
Gene