How to install a post on non-level sandstone?

cludelessdiwhye

I want to install this on a sandstone base: https://www.bunnings.com.au/jack-matrix-2-5m-black-screen-upright-with-installation-kit_p0361876

Unfortuantely the sandstone is not level. Short of chiseling back the sandstone (which I am concerned about doing in the event that I crack it), is there an easy way to make sure that both poles are plumb and on the same level?

JacobZ

Hi @cludelessdiwhye,

Can you post a photo of the sandstone where you're planning to install it? That will help us see how much variation there is and suggest the best approach.

In many cases, if the sandstone is only slightly out of level, you can pack out the lower side of the base plates with suitable non-compressible packers or shims such as these https://www.bunnings.com.au/titan-45mm-mixed-window-packers-100-piece_p0647625 . This will allow you to get both uprights plumb while keeping the tops aligned.

If the stone is significantly uneven, another option is to create a small flat mounting area from concrete for each base plate. This can be done by drilling holes in the sandstone, inserting reinforcing bar into the sandstone to anchor it to the stone, making a simple form around the mounting area, adding reinforcing, then concreting. This will allow you to create the flat area above the stone while still having a solid connection to it.

Chiselling or grinding the sandstone back would be my last resort. While it can give the neatest result, there is always some risk of damaging or cracking the stone, particularly if it's a natural sandstone slab.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob