GC/AAA Fences Semi Privacy Fence panels are made with 1" x 4" white cedar boards, fastened with aluminum ring shanked nails to 2" x 3" or 2" x 4" white cedar square back rails. The boards are fastened to rails with uniform spacing, the spaces depending on the particular style and customer preference. Styles include basic Semi Privacy or Board on Board (also known as ShadowBoard). Cap strips and fascia boards may be added. This style give a good amount of privacy while allowing for a small amount of wind to pass through the spaces.