Im laying artificial grass on 12m square. what aggregate / sand do i need and how much?

Hi the correct excavation depth for a artifical lawn installation should be 5 inc deep. It all depends how deep you have dug out that will determine how mutch aggregate sand etc that you need. Based on the correct excavation depth of 5 inc deep which allows for drainage you would need about 2.2 ton of stone and one ton of grit sand, the sand should be at the correct depth of 15 mm any thicker than 20mm can cause the turf to end up bumpy. These calculations are a near enough estimate Hope this helps.

It all depends on the area to receive the artificial grass. You could have level ground or a gradient which you would need 2l or 10ml dust hardcore then sharpe sand to get you to the level before you lay the artificial grass