How to Build a Wood Seating Bench
Decide on the style of bench you would like to make. Some benches have four individual legs, some have two wide legs and some even have six legs, with the extra pair in the middle of the bench. Also, the seat can either be a flat surface or have a slight curve to it.
Measure out the length of the bench. The seat area will consist of 1-by-4 boards, about 60 inches long. It will use about seven to eight boards. Cut the boards to length.
Cut the under support pieces. These will be made out of 1-by-4 boards as well and will be 36 inches long. If your bench will have two or four legs, you need only two support boards. If you use a middle set of legs, you will need a third support board. If a slight curve is going to be used, cut the support pieces with a jigsaw, cutting out a small slope in the middle like half of an oval.
Cut the legs for the bench. If you use post legs, they will be 4-by-4 posts cut 17 inches long. If the legs will be one large piece, it will also be 17 inches long, but 36 inches wide. The large piece will also have a cutout with the jigsaw to give it shape and to distinguish the legs. A half-circle will be cut out of the middle at the bottom of the large leg. Additional curves may be cut on the sides for design.
Cut the support beams for the inside of the legs. This will be the long board that connects the two legs under the seat. It will be 52 inches long out of a 4-by-4 post if the legs are posts, or a 1-by-6 if using the large side legs. If you are using the post legs, there will also be an additional support beam between the two legs that is made from a 4-by-4 post,11 inches long.
Connect the legs together. For the post legs, match the two sides up with the middle support beam. Cut a 1-inch-deep notch using the table saw for the beam to fit into. Place wood glue on the sides of the support beam that will then be placed into the notches cut out. Using nails or screws, go in diagonally to secure the beam to the wood post legs. This will create an "H" shape when done for each side.
Take the middle support beam and connect it to the two outside legs. For the posts, this will placed in the middle of the "H" support beam of the leg on each side. Using long screws, go in diagonally to secure it in place. For the large legs, the middle support beam connects to the middle of the leg on each side. Place screws through both pieces to secure it in place. For both types, additional steel brackets may be used for additional support.
Lay the seat beams over the supporting sides. Leave about 1/4 inch between each slat for spacing. Screw from the top of the slat into the support piece underneath. Use two screws on each side of the slat. Repeat this until the entire seat has been secured in place.
Attach the seat piece to the legs. Line up the supporting side to the leg base. Using screws, go through both pieces to secure it firmly in place.
Sand the entire piece until smooth. Brush off any extra dust. Apply a coat of paint or wood stain and allow to dry. Then, apply a second coat and allow to dry. Place your bench in place and enjoy.