Beecrofter wrote:
The commercial stuff is 40-60 mil poly.
=

Poly what ? !
Polyethylene, Polypropylene, Polycarbonate, Polyvinyl Chloride ...

I guess that you mean Polypropylene, I'd be interested if you meant
polyethylene as I have some damp proof course that may suffice.
I suspect that Polycarbonate would work fine also - I have some that
is 0.75 mm thick and very tough.
=

What is so hard about typing "rhizome barrier" into a search engine?

Nothing, but it is valuable to get a precision statement from a practitio=
ner.

=

Here is a blurb ripped off a dot.com
=

Many materials have been tried for bamboo containment. Concrete
cracks, metal rusts most plastics age and crack, rubber is too soft.
Polyethelene is the right material but must be thick enough to resist
penetration but flexible enough to handle and install. The American
Bamboo Society web site recommends barrier that "should be at least
0.040 inch thick". We have had customers bring us barrier that is .040
inch thick with a rhizome right through it. Bamboo Giant has
formulated a custom barrier material that is .060 thick, 50% thicker
than that recommended by the ABS. It is UV protected for long life and
has a plasticizer added to make it easier to work with.
=

Rolls are 148 feet long and weigh 115 lbs.

Interesting, there are evidently many ways to skin a cat:-

For reference, La bambouseraie de Prafrance
http://www.bambouseraie.fr/bambou/conseil.htm
sells polypropylene anti rhizome barrier - here's what they say:-
La barri=E8re anti-rhizomes BAR 70 que nous commercialisons se pr=E9sente=
en
rouleaux de polypropyl=E8ne de 70 cm de large, faciles =E0 mettre en =9Cu=
vre.

The barrier that I have bought from the Palm Centre
http://www.palmcentre.co.uk/ is 65.3 mm high and 0.8 mm thick
that is 0.0315 inches and very tough. Harder perhaps
than .06" polyethylene.

Out of interest, the polythene damp proof course I have is 0.6 mm
(0.0236 inches) and evidently not up to the job.

Thank you.
Richard