How to Build a Pergola Arbor

If you are looking for a way to add definition to an outdoor space, but don't want to close in a nice seating area, consider building a pergola. A pergola is essentially a wooden structure which provides a roof, but no shade and no wall. While it doesn't work as shelter, it frames an area and sets it apart from the rest of the yard. Building your own pergola is as easy as following a few steps.

Difficulty: Moderate

Instructions

Things You'll Need:

• 3 10-foot 2-by-4s
• 2 8-foot 2-by-4s
• 40 feet of #3 Rebar
• Tie Wire
• Cement
• Cement finishing trowel
• Four 12-foot pressure treated 4-by-4s
• Four 4-by-4 concrete brackets
• Wood screws
• Drill with screwdriver bit
• 19 10-foot 2-by-6 cedar boards
• Table or jig saw.
• Pencil
• Goggles
• Concrete screws
• Level
• Wood screws

Lay a Concrete Slab

1. Lay your slab. Using 2-by-4s, create a frame for your slab and place it on level ground. Reinforce the outside of the frame with pegs to keep the cement contained.

2. Pour a small amount of pre-mixed concrete around the inside perimeter of your frame. This will support the rebar placed in step #3.

3. Create a square using 4 rods of #3 rebar and set it on top of the wet concrete. Each rod should be at least 2 inches away from the wood frame. At each corner bend the pieces of rebar so they overlap at least 16 inches and secure it with tie wire.

4. Finish filling the frame with concrete until it reaches the top of your wooden frame. Once the concrete is poured, use a hammer and tap around the frame. This will help the cement settle and release air bubbles.

5. Use the extra 10-foot 2-by-4 to screed (level off) the top of the cement. Once the surface is level use the cement trowel to smooth out any remaining flaws and let it dry.

Building your Pergola

6. Measure an 8-foot by 8-foot square and place the concrete brackets at each corner. Once the brackets are in place attach your braces to them.

7. Place the 4-by-4s into the brackets and screw them in on all four sides. If you can put two screws into each side, you should. The point where your 4-by-4s meet the brackets is where the majority of the weight will be distributed so the more screws you have supporting this area the stronger your finished structure will be.

8. Attach the first set of support beams. Take two of your 2-by-6 boards and screw them onto two of the posts, so that the tops of the beams are 3 inches from the tops of the posts. Use two screws on each side for extra support. Attach two more of the 2-by-6 boards in the same manner to the posts on the opposite side of the square. When all the beams are attached they should be level to each other and parallel.

9. Measure one inch from the end of one of the 2-by-6 boards you have left and using a saw cut a two-inch wide by three-inch deep "notch". A notch is merely an indentation in the boards. Later the boards will interlock at the notches providing a snug fit that will make the structure even stronger. From the end of the first notch, measure 4 inches and cut another 2-by-3-inch notch. Make a set of these notches on the other end of the 2-by-6 boards. Do this on a total of 10 boards.

10. Place four of the boards on either side of the posts, on top of and perpendicular to the beams which are already there. The notches in the wood should line up with the support beams and interlock the pieces of wood.

11. Attach the other six notched 2-by-6 boards to the support beams in three pairs which are 4 inches apart. The pairs should be evenly placed about every 2 feet. Screw these pieces into the support beams.

12. Place your final five pieces of 2-by-6 perpendicularly on top of the cross beams. Mark where the cross beams touch the final pieces with a pencil. Then, make 2-by-3 inch notches which correspond with where the cross beams touch the wood. Place the final five beams on top of the cross beams and interlock them using the notches. Screw these pieces into the support beam

Tips & Warnings

• Pressure treated 4-by-4s often come with a wood veneer. Cedar veneers work very well because they withstand outdoor pests. Solid cedar cannot be pressure treated but the veneers give you the look of cedar and the strength of pressure treated wood. If you don't have a concrete slab, you can still follow the same procedure. Just dig four holes which are 18-inches deep and place your posts in there. Fill the holes with concrete and let it set overnight before building the pergola.
• Make sure you take precise measurements; if you are off with your notches, the pieces will not fit together.

References

• How to Build a Backyard Pergola: Simple DIY Woodworking Project
• How to Build a Concrete Slab