Measure the tree trunk to get the diameter. If the tree is young and still growing, add 12 inches to this measurement. If the tree is older and not growing quickly anymore, add 6 inches. Divide the number by 1.75. This is how long the boards closest to the tree will be. For instance, if you have a young tree with a 6-inch diameter, you would add 12 and divide by 1.75, or 10.3. So each inner board is cut to 10 1/3 inches.
Cut the inner boards from the decking material to the measurement determined in the first step. There are six boards altogether, and each end is cut at 30 degrees with a miter saw. Lay these boards around the tree after they are cut. Verify there is plenty of room between the boards and the tree.
Lay two more of the decking boards parallel to one of the first ones. Use 1/4-inch spacers between the boards. Use a pencil and straightedge to continue the 30 degree angle from the first board onto the next two pieces of lumber. Cut these two boards to size. Use these two boards to make five more cut boards of each size for a total of 10. Lay all the boards around the tree, making three rings that are 1/4 inch apart.
Cut the bench supports or legs. There are five of these supports and they are made of pressure-treated lumber and carriage bolts. Measure the distance across the three boards that make the seat of the bench. Cut 10 pieces of 1-by-4-inch lumber to this length. Cut 10 pieces of 2-by-6-inch lumber at the desired height for the bench. Many benches have 18-inch-high legs.
Build the supports. Sandwich two of the 2-by-6-inch boards at the top between the 1-by-4-inch boards. Use the clamps to hold this assembly together. Drill four holes, two through each leg and cross support. Insert carriage bolts through one side and secure them on the other with washers and nuts. Repeat this procedure for the remaining four bench supports.
Using one of the supports and two bench sections, attach the bench seat sections to the supports. Place the support on the joint between the bench sections. Use a drill fitted with a screwdriver bit and screw through the support and into the bench seat at an angle with wood screws. Use two screws per piece of bench lumber. Repeat this process with the remaining bench seats so you have three sets of two benches.
Set the bench assemblies around the tree. Prop the unattached ends of the benches on the remaining bench supports. Attach the bench seats to the supports. This time, screw down from the top, using two screws per bench seat piece.
Things You Will Need
- Measuring tape
- Deck lumber
- Miter saw
- Safety glasses
- 1/4-inch spacers
- Ruler or other straightedge
- 1-by-4-inch pressure-treated lumber
- 2-by-6-inch pressure-treated lumber
- C or spring clamps
- Drill and bits
- Carriage bolts, washers and nuts
- Wood screws
- Have a helper around when it comes to assembling the bench sections.