Waterfall Foam -- how sturdy for anchoring rocks?

[michey1st]

We are hopefully getting close (maybe in the next week or so) to when we can start rock work! I understand how to use waterfall foam to help direct the flow of water down falls, but watching the pond-digger videos, he mentions using it to "lock in" stones around the perimeter of the pond.

We are using a stacked wallstone (each around 6-10 inches wide and 1-3 inches high).

Here's the type of rock we will be using to give you an idea -- you can see the pallets in the background -- and don't forget to wave at my downy sunflower from last year ;-) :

We will be doing anywhere from a 3 stack, up to a 5 stack depending on location and thickness. I'm wondering if I foam in each rock, will that keep the rocks from shifting when leaning on them? If the rocks are of the bigger/thicker variety, will it make them safe to walk on without wobbles? Not sure how much hold this foam stuff really has, but I know that from the stacks of rocks we have done in flower beds, they tend to be wobbly with nothing to hold them together. Will foam fix that?

Have you done this?

Thank you!

 

[RobAmy]

The foam will help hold them but I would not trust 3 and 5 stacked high, especially to walk on. Larger stones are better if you can get them. My pond edge is fully walkable without the use of foam (except for waterfall flow) or cement. I just dry stacked them but used good size stones. Check out my showcase and under the construction I have some of the stone work pictured.

 

[addy1]

I used it to help anchor stones, not a cure all but it does nelp. I mainly used it on the pond edge where I would walk but the rocks would shift (down the slope pond edge)

 

[addy1]

btw like the stack of rocks! have fun. Sunflowers get eaten up here by the deer they love them.

 

[Big Lou]

Sorta snooping in on your discussion. Check this out please.

I've given thought to using the black waterfall foam to secure the 2 to 3 stone high wall that will rest against the approximate 10 degree side wall. The bottom support and some second row will be natural stone with the top row being my light weight Featherocks. The top row will extend above water and the banks edge. I am hoping to seal the rocks gaps to prevent debris from getting into the pond. After trimming the foam it should not stand out.

Thoughts please.

 

[michey1st]

btw like the stack of rocks! have fun. Sunflowers get eaten up here by the deer they love them.

Funny you should say that, Addy! Just this weekend, the tops of my sunflowers (1 plant multiplied to 6 this year) were mowed down by our four legged friends. This happened last year too, and the plant continued trucking along and put out all the flowers you see.

Guess it's time to hit the yard with Liquid Fence again.....

 

[michey1st]

Sorta snooping in on your discussion. Check this out please.

I've given thought to using the black waterfall foam to secure the 2 to 3 stone high wall that will rest against the approximate 10 degree side wall. The bottom support and some second row will be natural stone with the top row being my light weight Featherocks. The top row will extend above water and the banks edge. I am hoping to seal the rocks gaps to prevent debris from getting into the pond. After trimming the foam it should not stand out.

Thoughts please.

Hey, Lou! Snoop away! If I understand you correctly, you'll use the foam to secure rocks on a sloped surface? I think we have another ponder that tried that, and it ended up pulling her liner down (was reading a thread about it yesterday). a 10 degree slope doesn't sound like too much, though, so maybe you'll be ok? I'll let the experts chime in....

 

[Lisak1]

Here's my take on waterfall foam. It's waterfall foam. It does a great job for what it's designed for. With a little creativity it will also do a few other things - for example, you can hide small amounts of exposed liner with foam and a handful of gravel/sand. However, it is not mortar. What you see the Ponddigger doing in his ponds is using spray foam to fill spaces between rocks that are already well set. It's not integral to the structure of the pond wall.

Our goal when setting rocks around our pond was to make sure every rock around the edge could be walked on safely. I don't believe you can achieve that by stacking irregularly shaped rocks and trying to stabilize them with pond foam. You're really looking at something that should be done with mortar in my opinion. Stacking rocks 3, 4 or 5 high will result in rocks ending up in the bottom of your pond, even if you never walk on it. Nature likes to shift loose things around on all her own just for fun.

@Big Lou if I'm understanding your question correctly, I think you have a more workable plan. Stacking the flat stones with a wall behind them will provide stability. You would still want to play around with the rocks to find the best stack with the most natural "fit". As for using the pond foam to fill the gaps - I guess you could, but we have found that exposed foam (in our climate anyway) does not hold up over time. It starts to degrade within the first few years, getting very crumbly and dry. I guess you could foam over it again, but I am not a fan of using pond foam the FIRST time around - very messy business!

 

[Lisak1]

and it ended up pulling her liner down

If I remember that thread I think that ponder was trying to glue the rocks to the liner with pond foam. I don't think @Big Lou was planning that approach.

 

[Big Lou]

Correct

 

[michey1st]

If I remember that thread I think that ponder was trying to glue the rocks to the liner with pond foam. I don't think @Big Lou was planning that approach.

You're right, Lisa! I saw that Lou mentioned a slope, and didn't much pay attention to the %. Figuring out the math, a 10% slope isn't all that big a deal, so as you suggest, he should be fine.

For my application, my rocks will be on a ledge (undisturbed native soil on the bottom and behind, but I totally get what you're saying. We are restricting walking to outside the pond (on stepping-stone rocks on the ground), but it would be nice to have something not wobbly in case I need to lean in to futz with a plant or two.

Your advice and expertise is greatly appreciated!

Best regards,
michey

 

[Lisak1]

but it would be nice to have something not wobbly in case I need to lean in to futz with a plant or two.

And you WILL need to lean in.. that I can guarantee! And remember that even though you don't plan or intend for your wall to be walked on, someone WILL attempt to walk on it at some point. Or lean on it. Or sit on it. And maybe not a someONE but a someTHING - a raccoon, or a neighbor's cat, or a big bird. It's like the Law of the Pond! Anything that's not stable will fall in.

 

[addy1]

Turtles! I have had to redo some rocks that turtles end up walking on to drink from the pond, just small ones around my small ponds Ow they fall in and can drown.

omeone WILL attempt to walk on it at some point.

 

[michey1st]

And you WILL need to lean in.. that I can guarantee! And remember that even though you don't plan or intend for your wall to be walked on, someone WILL attempt to walk on it at some point. Or lean on it. Or sit on it. And maybe not a someONE but a someTHING - a raccoon, or a neighbor's cat, or a big bird. It's like the Law of the Pond! Anything that's not stable will fall in.

We've never messed with Mortar before, but I know my better half is just itching to try it. The only thing that has me a little worried about mortaring rocks in is the permanence of it. What if I want to change things up in a few years? Will it require a jackhammer or can it be chiseled apart? Is there a pond-safe off-the-shelf mix I can use or do I have to mix my own? Not gonna lie... the alure of something uber-stable is great, but it just introduces a whole host of new questions, lol!

 

[addy1]

^^^^^ @RobAmy he would be able to help, he does rock work.