We just finished up building and installing a monument sign face. We created this utilizing Dibond and cut vinyl.  The sign it replaced, was about 3 years old, but looked like it had been through hurricane Katrina.  The vinyl was pulling up in many areas, and the whole face was pulling off of the frame.  Some things we noticed in the creation of the original sign that we certainly didn't want to follow with our version included: printed then cut vinyl without any laminate and the face was mounted to the frame with some type of silicone. We knew we could provide a much more durable sign.  We utilized solid color cast vinyl.  This meant we didn't have to spend lots of time trying to match the color exactly on our printer.  It also meant we didn't need to laminate the vinyl as it already had good  UV protection.  The type of Dibond we utilized was made to be outdoors.  It was specially coated to provide the maximum protection from the elements.  We then used a sturdy double sided tape to mount the sign face to the frame.  This gave us a good firm attachment without leaving a huge mess. The install went very smoothly, and our customer is very pleased with the result.  Make sure your sign company isn't taking short cuts with your outdoor sign.