The most difficult part about building any railing is making sure the posts are well secured to the deck or stairs. Remember: People will be leaning against the railings, so make them strong. A post that extends up to the roof framing will be solid and secure. Short posts that support only the railing are more of a concern. Railing posts should be evenly spaced across a deck or porch and no more than 6 ft. apart. A good height for a railing is 36 in. to 42 in.
I like to notch railing posts to fit against the rim joist (see the photo below). A notched post,
installed with a couple of ‘/s-in. or ‘T-in.-dia. carriage bolts, makes for a strong and attractive installation. For a 4×4 post, make notches 1/2 in. deep and long enough so the notched post can cover the full width of the rim joist. If the top of the railing posts won’t be covered by a 2×4 or a 2x 6 cap, consider letting those posts run a few inches higher than the top rail and chamfering the top of each post. This technique, explained in the sidebar on the facing page, can enhance the appearance of any railing.
Posts for stair railings can be fastened to an outer stair stringer. Use carriage bolts rather than screws for stronger connections. At the base of a long stairway, where extra strength is required, the post can be anchored in concrete or to a steel post base embedded in concrete. RAILS AND BALUSTERS. Once the posts are installed, cut and install the rails. I use PT or cedar 2×4 rails for most of my deck railings. They can be fastened to the outside or the inside of posts, depending on the overall design of the railing. Some builders even notch their posts to accept the rails. No matter which method you choose, secure each rail-to-post connection with two 3-in. deck screws. If your railing design calls for top and bottom rails, install the bottom rail ЗУ2 in. from the deck.
Carriage bolts are strong and attractive. The rounded head looks appealing, and the bolt provides excellent holding strength for major structural connections.
