Hi guys, first time poster so go easy.
I'm wanting to build a raised patio having never done one before I'm struggling on a certain bit of knowledge. I've just constructed a step from the back of my house (getting doors fitted later this year) My back garden slopes away quite a lot. The path I have constructed the step on is already 100mm minimum drop to the grass. Im wanting the patio to sit 50mm above the current path so the paving can continue around the house. So my question is I know I need a minimum sub base depth of 100mm but everything I read says the grass must be dug up. Can I not lay my membrane on the top of the grass and then add my sub base without digging my grass up even though I've already got the depth for the sub base? I've added a picture to show the depth of each corner of the proposed patio. Thanks in advance for any replies.