Installing the posts
Most people who are not familiar with shade sails can’t believe how deep the post footings need to be. One of the most common shade sail failures is one where a post tipped in during a storm, not because the post itself bent or failed, but because the footing shifted slightly in the dirt. This loosens the sail allowing it to whip up and down which puts unnecessary stress and vibration on the hardware. The worst case scenario is that a corner comes completely free of the attachment point during the storm, creating a long whip that damages everything within reach.
These failures can be avoided by starting with a proper footing that won’t shift under storm winds. Since there are many types of soil, and the stresses on the posts are determined by the size and shape of the sail, we recommend consulting with an engineer on footing diameter and depth as well as post size.
Additionally, you must install the turnbuckles, shackles, and clamps properly so that even if the post tips in, they will stay secure and not let the sail come loose.
Large sails and high-risk projects should have back up safety cables installed to catch the sail if the hardware comes loose.
Rule #1 when installing a post – Don’t skimp on the footings!
Rule #2 when installing a post – See rule #1
Rule #3 when installing a post – See rule …
OK - you get it right? Don’t shortcut the footings
“So how do I know how big the footing should be?” The reality is that you’re not going to get a straight answer unless you pay an engineer to do the calculations. If you want a rule of thumb, make sure to bury 1/3 of your total post length in the ground. 1/3 in the ground, 2/3 out of the ground.
For example, if your post is 12 feet out of the ground it should be buried 6 feet into the ground. (This post would have a total length of 18 feet.)
Once you have 4 or 5 projects engineered, you will begin to get an idea of what it takes to properly secure a shade sail post.
Post Tilt Your posts should tilt away from the sail at a 5-degree angle. When you install the sail, the tension from the sail will pull the post inwards making it appear straighter and giving a much more pleasing look.
Digging the holes
Most contractors use a round auger attached to a Skid Steer to dig the holes. Make sure you have called the underground locating service to mark any utilities. Skid Steers don’t care what they dig up. Don’t be that guy that sends 100 employees home early because you hit the 480-volt line to the compressor room shutting down their golf club factory.
DigAlert is the underground service alert system for Southern California. First, you must Survey and Mark your proposed dig area with white paint, contact dig alert and initiate a ticket. Once you receive the all-clear from every utility on the list, you may dig with care. Contact your local Underground Service Alert program for more details.
If your hole is going to be inspected you will need to get all the dirt out of the bottom of the hole. Loose dirt may fail your inspection.
Tip: When you are trying to get that last bit of dirt out, pour a little water in the hole so that the loose dirt sticks to the auger. Don’t pour too much water as a soggy hole will fail inspection.
Good housekeeping will prevent a lot of fixing later. Keep the dirt on a tarp if it will contaminate the surrounding area. Make sure there is plenty of clearance around the auger and easy access for the Skid Steer so that you’re not replacing sidewalks, fences or planters.
Some hole locations don’t have enough clearance for equipment. If you have to dig by hand, again make sure to call the locator in plenty of time for them to mark any utilities, usually 2 days. Don’t skimp on the size and depth. A small jackhammer can make all the difference when you encounter caliche or rocky soil.
Setting the Posts
We recommend using wooden forms to clamp the post, holding it in place while the concrete is poured around it.
These forms are simple to make and keep the post up off the bottom of the hole so that concrete fills in underneath. You don’t want your post contacting the dirt or you will fail your inspection and allow the steel post to corrode over time.
If you have a deep hole and a heavy post you, should use equipment such as a reach fork or crane to lift the post into place.
TIP: If you don’t have access to a crane or lift and the post isn’t too heavy, you can still tip the post into the hole by hand. Use a board on one side of the hole to slide the bottom of the post in, kind of like a shoe horn. This keeps the end of the post from scraping the side of the hole.
Small jobs can be done with a mixer and bagged concrete. Once you need a yard or more of concrete it’s best to call in a truck and pump. You will usually need to provide a place for the concrete truck to clean out. This can make a big mess so plan ahead for where this spot will be or bring a cheap plastic swimming pool tarp to contain the mess.
If you use a pump, you need to account for the force with which the concrete exits the hose. Use braces connecting the form at the bottom to a place on the post 4 or 5 feet above ground to secure the post’s angle. Have someone steady the post in place as the concrete fills the hole. This will often mean pushing, pulling and wrangling the post to keep it in place.
Use a level immediately after the hole is full of concrete to set the final position of the post. Re-adjust the braces if necessary, don’t wait until all of your holes are poured or it will be too late. It will be tempting to move to the next post but don’t do it until you are satisfied with the current post. Spending a few dollars on “wait time” for the concrete truck and pump as they sit idle is well worth it to make sure your posts are correct.
Wipe down any concrete overspray from the post and your form bolts before it has a chance to dry completely. The concrete usually cures enough by the next day to remove the forms. This is a good time to take measurements for the sails and clean up the job site.