Things You'll Need:
- 4 6-by-6-inch wood posts, 10 feet long
- 8 2-by-8-inch wood crossbeams, 18 feet long
- 4 2-by-10-inch wood beams, 16 feet long
- 11 2-by-4-inch wooden rafters
- Drill
- Wood screws
- Shovel
- Gravel
- Wood braces
- Concrete
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Step 1
Measure out a rectangle with two 12-by-12-foot sections on one side and two 14-by 14-foot sections on the other. With each section marked off, dig a hole 2 feet deep where each 12-by-14-foot section intersects.
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Step 2
Fill holes with 6 inches of gravel. Place a 10-foot-long post in each hole. If needed, attach temporary wood braces to keep the posts in place.
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Step 3
Mix concrete and pour into each hole up to the soil line. Use a piece of wood to smooth out concrete and remove air bubbles. Let the concrete harden (approximately 24 hours).
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Step 4
On the 12-by-12-foot sides of the pergola, measure and mark 7.25 inches from the top of the main posts. This will be the location for the four main beams that will hold the trellis roof. Drill a 16-foot-long beam on to each of the 12-foot sides. The main posts on this side will be sandwiched between each of the main beams.
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Step 5
Install the eight crossbeams. These crossbeams will be installed above the 7.25-inch mark where the main beams were installed. Take two of the 18-foot-long crossbeams and place them running in the opposite direction of the main beams. They will run along the 14-foot section of the pergola. Drill the crossbeams into each side of the post. Again, the post will be sandwiched between two crossbeams. Repeat the same steps on the other 14-foot section.
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Step 6
Take the remaining four 18-foot-long crossbeams and add them as internal crossbeams. Attach crossbeams to the top of the main beams by drilling a wood screw at an angle through the crossbeam and into the main beam. Repeat for each crossbeam.
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Step 7
Arrange the 11 rafters on top of the crossbeams. These rafters will run in the opposite direction of the crossbeams to create the trellis roof. Measure for a clean and even look. Attach the rafters to the crossbeams with 5-inch wood screws.
