Foam Wall Instructable - A Full How-to, Step-by-Step Guide

Zeal · Apr 30, 2018

My mind is actually blown

sam.basye · May 1, 2018

Zeal said:
My mind is actually blown

Thanks, Zeal!

Merv Himself · May 16, 2018

A few days ago I started working on something similar, using Great Stuff. Your EXCELLENT step by step has inspired me, but also sparked many questions I hope someone can address:

1) I have found conflicting opinions regarding the safety of Great Stuff. I am just using the Original GREAT STUFF GAP & CRACK FILLER, not the black one for ponds. Some people swear that it is unsafe. Others says the only difference is that the "Pond Version" is black. My final steps will be carving the Great Stuff, then sealing it with Drylock. So will the type of Great Stuff I use even matter? (Hoping I don't have to start from scratch)

2) I made the mistake of trying to smooth out a small rough area with a heat gun. Unlike Styrofoam, Great Stuff did not melt nicely. It just changed into a softer material (almost like the stuff that's in your couch cushions). By doing this, have I created a material that is less safe for fish? Or will my final step of coating with Drylock, seal in any potential contaminants?

Thank you in advance for any help. Great forum!

sam.basye · May 16, 2018

Merv Himself said:
A few days ago I started working on something similar, using Great Stuff. Your EXCELLENT step by step has inspired me, but also sparked many questions I hope someone can address:

1) I have found conflicting opinions regarding the safety of Great Stuff. I am just using the Original GREAT STUFF GAP & CRACK FILLER, not the black one for ponds. Some people swear that it is unsafe. Others says the only difference is that the "Pond Version" is black. My final steps will be carving the Great Stuff, then sealing it with Drylock. So will the type of Great Stuff I use even matter? (Hoping I don't have to start from scratch)

2) I made the mistake of trying to smooth out a small rough area with a heat gun. Unlike Styrofoam, Great Stuff did not melt nicely. It just changed into a softer material (almost like the stuff that's in your couch cushions). By doing this, have I created a material that is less safe for fish? Or will my final step of coating with Drylock, seal in any potential contaminants?

Thank you in advance for any help. Great forum!

Thanks, Merv!

I’ve read of people using the regular great stuff without issue, but I have never personally used it. I’m not sure if there is something different in the formula that makes the pond foam “fish safe” or just black and UV resistant.

Not sure about heating the foam either.. I assume it would cure again after cooling and drying. You would have to seal it really well on every side to completely seal it though, if necessary, but it’s possible.

What are you trying to replicate with the wall??

Merv Himself · May 17, 2018

Hi Sam, and thanks for the response. I'm actually not building a wall. I am building a Tree Stump/Root Butress that is custom made because I could not find the exact thing I wanted anywhere else. My plan is to coat & color with Drylock and seal it thoroughly with 100% clear epoxy. I figure even if there IS something dangerous about the foam, the epoxy will prevent it from leeching into the tank.

Is my thinking flawed?

sam.basye · May 19, 2018

Merv Himself said:
Hi Sam, and thanks for the response. I'm actually not building a wall. I am building a Tree Stump/Root Butress that is custom made because I could not find the exact thing I wanted anywhere else. My plan is to coat & color with Drylock and seal it thoroughly with 100% clear epoxy. I figure even if there IS something dangerous about the foam, the epoxy will prevent it from leeching into the tank.

Is my thinking flawed?

Seems like it should work. Buy you a test fish just in case.

Post a pic of your stump! Sounds like a cool idea.

Merv Himself · May 27, 2018

This is what it looks like so far.

Still needs painting and additional texturing with tinted coats of drylok. It's basically a PVC skeleton and I globbed expandable foam on top of it, then carved it, coated it with cement, and the final step will be the tinted drylok in various shades. As mentioned I was thinking about coating the final masterpiece with 100% Clear Epoxy, but I really don't want it to look shiny when submerged. Feedback/Suggestions welcome. - Merv Himself

P.S. Thank God my neighbor lets me sneak over to her house to work on projects like this. My Helen would blow a gasket if I worked on stuff like this in OUR kitchen!

sam.basye · May 27, 2018

Merv Himself said:
This is what it looks like so far.

Still needs painting and additional texturing with tinted coats of drylok. It's basically a PVC skeleton and I globbed expandable foam on top of it, then carved it, coated it with cement, and the final step will be the tinted drylok in various shades. As mentioned I was thinking about coating the final masterpiece with 100% Clear Epoxy, but I really don't want it to look shiny when submerged. Feedback/Suggestions welcome. - Merv Himself

P.S. Thank God my neighbor lets me sneak over to her house to work on projects like this. My Helen would blow a gasket if I worked on stuff like this in OUR kitchen!

That’s an impressive root!

I’ve never put on enough epoxy to “seal” and of my walls, so none of them came out shiny. A light brushing, enough for sand to stick, is dull. Can’t say for certain about a thicker layer.

I think as long as you soak the root and change the water frequently, the cement should leach out in few weeks. I’ve seen people build walls out of concrete over pvc without sealing them. Just gotta soak it to leach all the chemicals out.

As long as your Helen knows you are in your neighbors house! Haha