Pond Boss Forums POND CONSTRUCTION Building a dam here goes .. dam going in

Mike:

FWIW, I found out that they use black expanding foam when building decorative waterfalls and ponds near houses to keep the water from going between two rocks when they are set on top of each other. I don't know if you would want to do something like that with the smaller rocks to keep the water where you want it. The cans of black expanding foam are $10-$12 each, but I think the expanding foam that you'd use on a house to seal voids would be almost the same thing, except it might not have all of the UV protection (paint would offer UV protection, you could brush the exposed surfaces). Locally, Lowes has a sale on the house expanding foam. Hi-expansion cans are $2.00 and change, the Low-expansion cans are right around #3.00 each. That's down from $5-$6/can a month or so ago.