Yes, there are several solid and safe methods to tie two shorter 4x4 posts together to create a longer post for supporting a railing for outdoor steps. Here are a few common techniques:
Butt Joint with Bolts: This method involves joining the two posts end-to-end with a butt joint. Use a saw to create a clean, flat surface on the ends of both posts. Apply wood glue to the joint for added strength. Then, insert long bolts through pre-drilled holes in both posts and secure them tightly with washers and nuts on each end.
Half-Lap Joint: A half-lap joint involves notching half the width of each post to create a flush joint. Measure and mark half the width of the posts on both sides. Use a saw to carefully remove the marked portion from each post. The resulting notches will fit together snugly when the posts are aligned. Apply wood glue to the joint and secure it with screws or bolts for additional strength.
Corner Brackets: Utilize metal corner brackets specifically designed for joining posts. These brackets typically have flanges that attach to the sides of each post, providing a secure connection. Align the posts and attach the corner brackets using screws or bolts. Make sure to choose heavy-duty brackets suitable for the load requirements.
Metal Splice Plates: Metal splice plates are flat metal plates with pre-drilled holes used to connect posts. Place the splice plate on one side of the joint and align the holes with corresponding holes in both posts. Insert bolts or screws through the plate and posts, and secure them tightly with washers and nuts.
Whichever method you choose, ensure that the joint is secure and provides sufficient stability for the railing. Consider consulting with a professional or experienced carpenter if you're unsure about the structural integrity of the joint or the specific requirements for your railing.