vbl

Going to build a frame to hold an 8' wide x 4' tall double sided aluminum advertising sign. Going to use 6'' x 6'' treated post 14' tall(4'below ground). Plan to groove 2 x4 or 2 x 6 with a .25'' wide x .50 deep dado to make frame. Going to screw frame to post. How do I join the corners of frame(that joint will be the major stress point)?? Or should I not build frame and groove post to receive sign and use 2 x 6 above and below sign? Any suggestions please.

C&D Woodcraft

For starters, I wouldn't miter the corners. If you grove the post at least the weight of the sign would be sitting on the bottom of the post grove as opposed to the frame. But I do think a frame would work and would look better. If you do do a frame (all 4 sides), I'd just make sure the top and bottom rails butt into the post as opposed to butting into the side frame. That way you'd at least be able to put an angle bracket or some additional blocking under the joint attached to the post. Are you using PT lumber for the frame? If so, I'd be a little concerned that the top and bottom rails may warp.