We did not pour cement reinforcements for the trellis, as we were going to stay above the frostline, and it was not going to be very large (and thus didn't have to support too much of a load). We built this in 2006, and after 5 years (with lots of rain and snow storms) it is still doing just fine!
What you will need:
posts: pressure treated 4x4s, 8' long, 4 of them, $15 each ($60)
front and back cross pieces: pressure treated 1x6s, 6' long, 2 of them, ($10)
left and right cross pieces: pressure treated 1x4s, 42" long, 4 of them ($15)
top cross pieces: pressure treated 2" square balusters, 4 feet long, 7 of them ($.89 each)
wooden ladder trellises, 2 of them ($20)
wood deck screws
post hole digger
saw (hand saw)
drill and bits
rocks and bricks
pencil for marking lines
All wood we used was pressure treated except for the side trellises.
Note: this is the step by step instructable for this photo instructable, as part of the Share Your Garden Photo Contest:
Home-built Garden Arbor
Don't forget to vote!
Step 1: Plan Arbor Dimensions and Choose a Site
Choose an appropriate site. Make sure that there are no pipes, roots of trees or large bushes, or major rocks (boulders) where the posts should go.
Step 2: Cut Pieces to Length
Step 3: Dig Holes for the Posts
We dug about 1', which is on the low side but the structure has been sturdy enough to withstand many seasons. We had found conflicting advice on the internet on whether or not we should pour concrete footings, but discovered we were able to get away without them. However, please note that if you are going to set posts much deeper, it is advisable to pour concrete footings.
We were not that skilled with the post hole digger, and the holes wound up considerably larger than our posts. So, we inserted two (the left and right of the front pair) and temporarily stabilized them by filling the gaps in the post holes with rocks and bricks.
Step 4: Attach Front/back, Left/right Cross Pieces
Attach the front cross piece (1x6s) to the outer surface of the posts, using the wood screws at each junction. Make sure it is centered. Repeat for the back left and right pieces.
Then attach the left and right cross pieces (1x4s). There are four of them (each "bracketing" the vertical posts). Attach these below the front and back cross pieces, using deck screws at each joint.
Step 5: Attach the Top Lattice Work
Optional: we wanted a hanging lantern, and had a set of two solar powered LED garden lanterns, so we stole one from the hanging lantern and attached it to the cross pieces with wire.
Step 6: Attach Trellises to the Sides
And you're done! Note: we opted not to paint or stain the arbor, as we wanted the natural wood appearance.