I poured 6 bags of this stuff onto a concrete basement slab in a new
bathroom. Seemed to do the job relatively well, but recently started
cracking. These aren't hairline cracks, but up to 1/8".
The instructions on the bag made no mention of paint on the concrete
slab (pro or con). I have paint on the floor.
Any ideas on what to do with this? I'm guessing that I'll have to rip
it out. What I really want to know is what to do next time to avoid
this painful and expensive mistake.
Thanks in advance.
First off, I've used self levelling before with varying results but never
cracking. Did you use the proper bonding agent (ie. it appears
to be some sort of epoxy binder that you paint onto the floor)? I also seem
to remember that you have to clean the slab of paint and such
for this to bond properly.
Thanks for the responses. First, no I didn't use a bonding
agent/primer, since, reading the instructions on the bag, they made
reference to the fact that it was sueful in avoiding pinholes in the
finished surface, not that it was necessary to prevent cracks. Having
read a bunch of stuff last night, I realize that was a mistake
(expensive too). They also don't make any reference anywhere (website,
instructions on bag, etc. ) to paint being an issue (ouch again). I was
thinking of laying down a layer of kerdi or embedding a plastic or wire
mesh into any new layer. Any thoughts on that?
Kerdi is Schlutter's waterproofing membrane, Ditra is their uncoupling
& waterproofing membrane.
You have options:
- embed 1/4" Hardie backerboard in thinset.
- use an isolation membrane. The manufacturer will specify the size
of crack it will bridge.
- fill the cracks with a pourable two part epoxy such as Git Rot.
- take a flyer that the stuff won't move anymore and that the thinset
will fill the cracks.
Well, thanks to all who responded. I'm resigned to the fact that I'm
ripping it all out. I've also looked at different products and options
and I think that I'm going with Mapei Ultraplan1 and UltraPrime L primer
and, as per their instructions, grinding the paint off the surface with
a diamond grinder (hopefully HD or Rona have those available for
rental). One thing I like about this product is that they make it clear
what has to be done before the product can be applied, as opposed to the
EZ Flow product, which didn't say either way that it shouldn't be
applied over a painted surface.
I'll let you all know how it went.
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