As a professional sign maker, I would like to make a few suggestions. I recommend making the frame only one 2x4 deep by using lap joints at the corners. Lap joints are fast and easy to make using only a circular saw and a chisel. Wood glue can be used when screwing together for extra long term rigidity. With the frame constructed in this way you have two options for mounting your banner that are very clean and don't show ugly fasteners. With square corners you can wrap the banner around the edges and secure it to the back of the frame, folding the corners the way you would when stretching a canvas over a wooden mounting frame. The other option, which is much nicer, would be to finish the perimeter of the frame with 4" aluminum fascia and matching paint, if necessary. Use 1.5" foam insulation inside the frame as a solid support for the banner in windy conditions. For a two sided sign mounted between two posts, I would recommend placing two frames back to back with a sheet of edge sealed, primed and painted 1/2" MDO sandwiched in between. For single sided signs just use the MDO mounted to the back of the frame. Use 7" lag bolts to mount the frame between the posts, and place a few washers between the posts and frame as a spacer to allow room to apply the fascia to the perimeter later. Mount some 1.5" foam insulation inside the frame for a flat surface to support the banner in windy conditions. Apply the banner to the frame, paint anything that needs paint, and attach the fascia.

Thank you! This is awesome!

Nice Work!

Great job

Banner Installation, Building a Frame for Long Term Display

is THAT 2 X 4 CMS OR INCH TIMBER?

It's "taut," not "taunt," unless you're actually provoking your banner into a fight.