Arbors are extremely versatile structures. They can provide partial shade on a bright summer day, or act as a grand entrance to your magnificent garden. In the following paragraphs we will show you how to build a simple inexpensive garden arbor. This is a simple structure that will make a big impact in your garden, entrance or pathway.
The materials used in this project are listed below, as well as all the tools you will need.
- Tape measure
- Circular saw
- Posthole digger
- Spade drill bit ½ “
- (4) 4x4x8 PT
- (7) 2x6x8 PT
- (2) 2x4x8 PT
- 2 ½ “ deck screws
- (8) ⅜” x 3” lag bolts
- (8) 60 lb bag concrete
- (4) ½” concrete
- (4) anchor bolts
- (1) 6” Sonotube (round cardboard concrete form)
- **PT stands for Pressure Treated
It’s nothing more than two sets of 4 x 4’s connected by a 2 x 6. More 2 x 6’s are strung from one set to the other.
To lay out this project begin by placing a stake in the ground where you want the first post to be. Our four posts are going to form a 72.5 inch square. Measure 72.5 inches over from your first stake and place another stake.
THE 3, 4, 5 TRIANGLE METHOD
Use the 3, 4, 5 triangle method to make things square. The legs of a right triangle have these properties. Place 2 boards perpendicular (90°) to each other at the first stake. Measure from the stake 4 feet and place a pencil mark. Now measure down the other board 3 feet and mark with a pencil. Measure from one mark to the other (this is easier with a partner). Move a board one way or another until it measures 5 feet. Once it does, then the two boards are perfectly square to one another.
Once you have your boards perfectly square, measure another 72.5 inches from the stake in the corner of the boards and place your third stake. Repeat the layout tip above to place the 4th stake. Now you have a perfect square for your new garden arbor.
This simple design can be placed just about anywhere. Now it’s time to dig. Use your post hole digger and dig down at least 18” deep. If you plan on attaching the arbor to a permanent structure then you need to dig below the frost line for your area.
Once your holes are deep enough cut up your sonotube (cardboard concrete form) into 4 pieces. Place one in each hole to extend above the ground. These are going to form the “foundation” for your new arbor.
Time For Concrete
Begin to mix up your concrete, just like we did in our outdoor kitchen project. Get it to a peanut butter like consistency and then scoop it into your freshly dug holes. Use a stick with an up and down motion (like churning butter) to help remove the air bubbles in the concrete.
When the concrete is near the top of the hole, place your sonotube over the hole and fill it the rest of the way. Use a trowel to level off any excess and allow the concrete to set up about 20 min or so.
Insert the concrete anchors directly in the center of the concrete form. Leave about 2” above the concrete. This is what will hold our 4 x 4’s in place after the concrete sets up.
While waiting for the concrete to set up take all of your 2 x 6 boards and cut a 45° angle on the bottom side of them (see the figure below). You can get creative here and cut whatever fancy shape you like. As long as you cut them all the same it will look great.
Set the cut pieces aside, we will be using some of them later when we put this thing together. Now place an X on the bottom of each 4 x 4 by drawing a line from corner to corner to find its center. Drill a ½” hole 2 ½” deep into the bottom of each 4 x 4.
Putting It All Together
After the concrete has set for a day or two place the ½” hole of your first post onto the anchor bolt that’s sticking up from the concrete. Do the same for the post that will be directly across from it.
Measure from the bottom of the post up to 91 inches and draw a line. Grab one of the cutoff scrap pieces from earlier and clamp it under the line you just drew. This will hold the first 2 x 6 in position while you set the other end of it.
Mark a line at 10 inches on both ends of the 2 x 6. This will be the 10” overhang on both sides. This next step may require a partner to make things easier.
Place one end of the 2 x 6 on top of the clamped scrap piece. Hold the other end up on the other post. Place a level on top of the 2 x 6 and get it level. Slide it until the line you drew at 10" on the 2 x 6 is even with the outside of the 4 x 4 (10” overhang). Now clamp it in place.
Pre-drill the clamped board for the ⅜” lag bolt. Bolt in place but do not completely tighten it. Go back to the first post where the 2 x 6 is resting, and adjust if necessary to the line you drew making the overhang. Clamp it in place. Pre-drill and lag bolt it together. This time you can tighten it down, and go back and tighten the other side.
Remove your clamps and then repeat the same steps for the other side. When done you will have two sets of posts with a 2 x 6 across them facing each other.
Take the remaining 2 x 6’s and bundle them together with a clamp, angle cut side up. Be sure they are even with each other on the ends. Now measure in 10” from each side and draw a line across all the stacked boards. A chalk line works well for this.
From the line you just made, measure 1 ½” outward toward the angle cut on both sides and create another line. Set your circular saw to it’s deepest depth (about 3 inches) and cut along the lines you made.
Now cut repeatedly about every ⅛” or so between the between the lines to create a 1 ½” grove on each board (remove the grey area from the image above). Use a chisel to clean out the bottom of the cuts and make them all flat and uniform.
Unclamp the bundle and you are left with the 5 top pieces with evenly cut grooves.
Place one of the grooved 2 x 6’s perpendicular to the 2 x 6 that is lag bolted to the 4 x 4. Place it on the outside of the 4 x 4 that the header board is on, this will keep an overhang.
You may need to use a hammer to tap it in all the way. Do not hammer directly on the 2 x 6. Use one of your scraps from earlier and hold it on the piece and hit that directly with the hammer. You will avoid marking up your wood using this technique.
Space the remaining boards evenly across the arbor. See the picture below. Pre-drill holes at an angle then use deck screws to secure the grooved boards to the main lag bolted board. Always pre-drill to prevent the wood from splitting.
Now it’s time to add our stabilizers. Cut a 2 x 4 at 24" inches long at a 45° angle. Cut the same 45° angle on the other side. Pre-drill and screw to attach one end to the post. Screw the other end into the main 2 x 6. Do this on all 4 corners to stabilize the entire structure.
Repeat the above steps for the other sides of the 4 x 4 and attach to the other side to the board running from header to header.
If you used pressure treated wood it is a good idea to wait 6 weeks or so before finishing it with sealer or stain. Allow the wood to dry out a bit before adding finish.
The arbor in the picture above is over 12 years old. This picture was taken in the winter (not a flattering time of year). As you can see it could use a fresh coat of stain to bring it back to life.
If you followed along with us, you now have a grand entrance to your garden! A home for flowering vines and hanging baskets. Simple design with a bold statement.
A project like this is simple enough for a beginner and yields awesome results. Don’t let another season go by. Give this project a try, you won’t regret it! Until next time enjoy your backyard water garden.