Waterproofing compounds

9 years ago

Yeah, I know...it's been discussed ad nauseum in the past, but wondering if there were any recent 'discoveries'....

I've got a small, free-form concrete pond in the backyard. It was apparently neighborhood "fashion" at some time past, though only three still survive. It's primary purpose was to provide a breeding area for toads, as they eat slugs. Slugs are the enemy of all gardeners, but that fungal disease (dideomycosis? sp?) has eliminated them from the ecosystem.

I put in a liner a decade ago, but it appears that the material - purchased at the local big box hardware store - was *not* EDPM. It has failed miserably. For-real EDPM is rather pricey and for that an other reasons, I thought I might try some kind of cementious coating, like Thoroseal. Drylock was considered, but I think I need something more than mere paint. Tried that rubberized FlexSeal crap "as seen on TV" on a concrete birdbath, but it was an abject and total failure. No wonder the can sez "not for architectural use"....

Years ago, there was a basement waterproofing around: cement based but with 'tiger hair' or chopped fiberglass as a reinforcing/bridging agent. Can't seem to find anything like this today, though I guess I could add this to any other cement product I buy. Any suggestions?

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Comments (5)

apg4
Original Author
9 years ago
Correction: Chytridiomycosis.... The "edit" function has vanished....
apg4
Original Author
9 years ago
last modified: 9 years ago
Did some more research on Thoroseal - it's NSF-approved for potable water systems like cisterns. For fish, the company recommends a week-long dry cure followed by a brine wash: one pound salt to one gallon water. Scrub this around and rinse off 24 hours later. Repeat rinse 'til water runs clear.

The main reason was cost; that, and the fact that the previous membrane failed so completely. A 10x12' hunk of EPDM will cost $135, plus shipping. That's $1.12/sq. ft. A 50 pound sack of Thoroseal will do two coats on - supposedly - 250 sq. ft. At $36 (no shipping, local purchase), that's $.14 per sq. ft.

It can also be used for chimney crowns, another job I gotta do since I just rebuilt the 37 year old Vermont Castings wood stove. Being retired, that bucket of " 'round tuits" seems to be multiplying rapidly.... ;-(
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groundbeef1
9 years ago
I just bought my EPDM liner on Amazon. I'm a prime member so the shipping was free. ( How I get free shipping on a 120lb box I'm not sure...but whatever). Cost wasn't too bad @1.20/foot. I have a rectangular pond, so the 15x20 liner was perfect. I thought of coatings, but couldn't find one that would apply properly to the wooden sidewalls.
trickyputt
9 years ago
last modified: 9 years ago
I love mixing polymers into cementatious mixes. One fave is redguard with epoxy based thinset with tile on top. But get enough poly into it and its really cool what can be done. The idea is mineral protection for the polymer seal of course.
apg4
Original Author
9 years ago
last modified: 9 years ago
An update on the project....

Results look pretty darn good. I ended up using three coats, mixing Acryl-60 polymer (made by the same company, BASF) in with the Thoroseal according to the directions on the package that I scaled down, working with about 10 pounds at a time. (The more expensive ThorosealSuper already has the polymer mixed in.) The issue is that the mixed material has a pot life of about 30 minutes, so you don't want to mix more that can be worked in that time.

I considered masonry colorants - most a variation on 'red' or 'terra cotta'. All use ferric oxide, AKA rust, as the active ingredient. Wasn't sure how liberal amounts of rust added to the mix would affect the strength of the cement or the health of the fish.

Package directions called for a week of curing, so with the current rainfall, I'm filling up the pond. Will do that several times before the fish go back in.

Cheers