I am planning to purchase and install in our backyard a square shade sail ( Coolaroo ready to hang 3m Sq, shade sail) , I plan to anchore one side of the sail on the brick wall ofthe house one corner to a corner fencepost 4 meters away and the other corner to a gum tree 6 to 7 meters away .
I needto know what I need to get in terms of materials , I have ahammer drill but no large bits.
Welcome to the Bunnings Workshop community. It's wonderful to have you join us, and thank you for sharing your question bout installing a shade sail.
There are many forces acting on the shade sail both static and dynamic. While the shade sail is still, the anchors only need to hold the weight of the sail which is relatively easy. But when the wind starts blowing onto the sail the pressure generated can reach as high as 500kg of force. That force is transferred to the anchor of the sail and if it is not secure will rip out the anchor easily.
You can imagine having to guess how much force will be necessary to yank out one of the bricks in your wall? Or perhaps how much force will be necessary to tip over a fence post that has a shallow foundation? Putting an anchor on a tree is a wild guess. It might work, then again it might not. This is why we often recommend using independent fence posts that are properly anchored into the ground.
You can use either steel or timber posts. I recommend using a turnbuckle to keep the shade sail straight and taut. I suggest engaging the services of a builder to determine how deep and how big the hole should be dug for the posts. It's always a good idea to have a look at your local council's rules and regulations regarding the installation of shade sails.