I used a bunch of leftover shingles upside down and then used tar paper on top of that.
Has worked out fine and had a use for the leftovers from a roofing project.

Bob


wrote:

you really dont want aluminum in contact with the liner. but get carpeting padding
(they often toss big pieces out ... check with local carpeting store). carpet
padding hasthe advantage of not being natural and it doesnt decompose and it doesnt
usually support fungal life under there. it is luxurious to walk in my pond and have
the soft pad cushion my feet. it also drapes wonderfully and stays put when the
liner goes in. Ingrid

(John) wrote:

Hi,all:
I am going to build my first pond, I have some old aluminium roof
(there are trash to me anyway), I am thinking about put the aluminium
roof under the liner to prevent the tree root from penetrating the
liner, will this work? or there are better ways ? please advise.
Thanks in advance.
John