To begin, find the center of the post and pull in on both sides of the deck to the center post measurement. Next, get the center of post to center of post measurement. Then, divide the number of rails by the overall measurement. This will give you the center to center of post measurement. Once you have this measurement, you can then measure and mark all your posts. After marking your posts, it's time to cut blocking and nail the blocking vertical through the rim board and the adjacent joist. You will need two blocks per post. This will provide a sturdy foundation for your railings and ensure that they are properly secured to the deck. It's important to take your time with this step to ensure that everything is level and secure. With proper rail blocking, you can enjoy a beautiful and safe deck for years to come. #deck #doitright #deckbuilder #howto #custom #builder #deckbuilding #deckguide #howtobuild #build