More in Outdoors
To get started with the arbor, the first step is to seal the concrete. Concrete sealers penetrate up to 1" into the porous surface forming an impervious barrier. Sealing helps to prevent water damage and helps to keep stains from soaking into the concrete. Before sealing, the surface needs to be completely clean. So, wash your patio with water, a scrub brush (Image 1) and mild detergent. For a quick job, you can use a pressure washer.
Apply the sealer liberally, but evenly (Image 2). Be careful not to allow the sealer to puddle. You may need to apply a second coat of sealer, depending on how porous your slab is. Just make sure that you allow for proper drying time between coats.
This will take about 6 hours to dry for light foot traffic, but since we are building an arbor over this slab, we'll give it 24 hors to make sure it's dry before we start.
While the sealer dries, construct the posts. Start by cutting your 2"x6"x8" pacer blocks (Image 1). For this project, we should need about 18 -- two for each of the 6 posts, plus a few extra for the temporary tie beam support.
Sandwich the spacer blocks at either end and between two 2"x6"s (Image 2); secure with galvanized screws.
At this point, don't worry about the height of the posts. Once you've determined the correct height of the arbor, then you'll sandwich another spacer block to temporarily support the tie beams as you install them.
This post design works well when adding an arbor on to a deck. Just position a spacer block 6 to 8" away from the bottom end of the 2"x6"s, making a fork that will fit over your deck's joists. Secure with lag screws.
If you were setting all your posts in footers in the ground, you'd lay out the location of your arbor using stakes and twine to check the squareness -- but with this particular project, the concrete patio butts up directly against the house. So, half the posts will need to be secured in or onto the concrete patio, and the other half will need to be placed in footers directly in the ground. Because of this, we can't lay out the location so we'll be checking squareness at each step along the way by checking distances, checking for a plumb line and levelness.
Let's start with the posts just off the edge of the patio: The first step is to dig footings to the frost-line depth (the frost line varies from region to region).
To dig the footers, you can use a manual post-hole digger, seen here, or a the gas-powered auger to save time.
Each post needs to be at a distance of 4 to 6 feet away from each other. Measure from the first hole, dividing up the remaining distance between each of the posts. Here we just need two more posts.
Once the holes are dug, fill each with about 6" of gravel. Tamp the gravel. Place the post in the hole, and make sure it is plumb.
Next, pour fast-setting concrete around the post in the hole and check for plumb again. Tamp the concrete to release any air bubbles. Then pour more concrete to fill the hole approximately 2" above ground level, and slope it away from the post to divert water.
While those posts set up, the focus is directed to the other posts that need to be secured on the concrete patio. One way to handle this is to remove the concrete patio entirely; another way to handle it to remove the concrete slab and re-lay it.
Now, it's important to place these post anchors at least 2" away from the edge of the concrete slab. This will allow for the maximum load on the concrete without causing the slab to crack.
After measuring from one of the posts in the ground and marking the location, use a hammer drill and drill a hole into the center of the marked location on the concrete slab.
Apply a masonry expoxy to a masonry screw, then place the screw in the drilled hole (Image 1). Next, post anchors attach to the masonry screw with the washer that came with it. Simply place the anchor over the screw then using the washer and tighten until the anchor is secured.
Now, set the post onto the anchor (Image 2). Check for a plumb position using a level; if the post isn't plumb, place some wooden shims under the low end of the post until the level shows the post is exactly plumb.
The initial step is to take two measurements for the posts: the first is for the 96" ceiling height (Image 1). This is the place where the tie-beam will rest, so we want to put in the temporary space block here. There's no need to drive the nails in all the way, because once our beam is secured into place, we'll remove this block.
The second measurement is for the height the post will rise above the beam. Once this measurement is marked, use a reciprocating saw to make a straight cut across the top of the post (Image 2). (If a different look is desired, the top can be cut and marked accordingly.)
Now we continue around to each post, marking and blocking the ceiling height and marking and cutting the excess post off the top.
With the posts cut to height, it's time to install the tie-beams. We begin by measuring the distance between the first two posts (Image 1), keeping in mind that we'll want to have some overhang from the posts; another option would be to notch out the ends that hang off the tie beam for a more decorative look.
Begin by setting the back end in place in its slot (Image 2); then lift the front of the beam into its slot. Measure to make sure you have the desired amount of overhang from the posts, then remove the temporary support blocks. The result is a design that's airy and open, with sturdy, stable posts.
To attach the rafters to the tie-beams, measure the length that you'll need for the rafters. Remember you'll want to have some overhang and cut your rafters. Continue by setting the remaining rafters. The space between each one should be about 2'.
Cross beams are the final addition to the arbor; they'll provide more shade and extra support for any climbing plants.
Position a 2"x2" cross strip about 6" from the ends of the rafters. Center the strip so it extends past the outside rafters by about 6".
Drill pilot holes through the cross strip and into the rafters, then attach the cross strip with galvanized screws.
Finally, add the remaining cross strips, spacing them about 16" apart.