"Richard" wrote in message
...
I've used paving stones (flags) to create a root barrier. When I dug up
the garden there were tree roots just below the surface emanating from a
row of trees that were planted about 20 years ago. Don't know what trees
they are, but they are those fast growing evergreen types. Look a bit like
Christmas tress.

Anyway, the flag barrier is 61 Cm deep(2 ft)from the surface of the
garden. But, between sections there is a gap between the flags of about
4mm or 5mm.

QUESTION: Do I need to plug the gaps between flags, or will I be okay
leaving the gaps? Thanks.

I'm doing a similar thing on the allotment. I'm putting the slabs in
alternate ways round, so that the ends meet nice and snug because of the
chamfers. Another option would be to overlap the slabs. But I expect some
roots will always find a way through unless you use concrete.

Steve