Originally Posted by playfordtree

The black plastic is probably 1.5-2.5mm thick, i cant really remember, i just bought the thickest chit i could get.
There is a small gap between plastic and base of pool.
Also when we laid the sheet down it wasn't one piece, we had to lay a couple of bits to get complete coverage, one peice overlays the other.
So maybe the roots could get in between the two sheets?
I think i might just err on the side of caution and put the barrier in.

(dammit that means i have to dig holes, i hate diggen holes, im a treelopper not a bloody ditchdigger)