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Thinset on Concrete Block?

JohnD1's picture

The basement is being cleaned up--but it is still a basement. It has tools, workbench, etc. The outside was recently water "proofed" and additional drainage added along the foundation.

The block is messy on the inside. There was some spalling, and there has been other damage that has occurred in the past 80 years.

I have some thinset left over from my bathroom project. After getting rid of the loose stuff on the surface, is there any reason why I could not use the thinset to get a smoother surface?

I was then going to paint it with some leftover waterbased paint, just to brighten the place up.

(post #87799, reply #1 of 16)

Actually, I don't know why this would not work, but a good alternative is to buy some bags of "B-Bond."  It goes by different names...fiberglass reinforced cement by Quickcrete, etc. Basically, its just portland and chopped fiberglass with a few other dry additives. It comes in grey or white. Trowel it on to a thickness of 1/8 inch  or so and let it dry. It does a good job of waterproofing, it smoothes out ugly mortar joints and it brightens up the walls.  It costs around $12 a bag...a bag goes a long way.


 


But the thinset idea sounds good...never tried it though.

(post #87799, reply #2 of 16)

Thanks.  And, if I run out of thinset, I will check out that reinforced concrete mix.

(post #87799, reply #3 of 16)

Thinset is way too soft.  think of it as a adhesive, not as another cement product.  it only hardens to something like 400 psi.


What another posted recomended is what you need.  I've also seen it called "surface bonding cement"

(post #87799, reply #4 of 16)

Thanks.  I had only been thinking of it in terms of appearance.  Other walls in the basement have drywall, which is even weaker.


That said, you bring up a really useful point.


(I hate it when people bring up reality, making me have to reconsider doing something.)

(post #87799, reply #5 of 16)

I've used thinset before for similar things. Worked fine.

One nice thing is that it "machines" much easier than most other patch materials.


As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

(post #87799, reply #6 of 16)

The thinset will be pretty dark, though, and may take several coats of paint to cover. And I'm not sure how well it'll take water-based paint, since it's not as porous as most masonry materials.


As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

(post #87799, reply #8 of 16)

DW and I just used thinset to coat some marching band props. It was over 2" foam board and was painted a light sandstone color with some left over latex paint. Only took the standard two coats to get good hiding.

(post #87799, reply #9 of 16)

Good to hear.

So with that said, there's no real reason to not use the thinset, if it's "free".


As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

(post #87799, reply #7 of 16)

 Just mix some "rich" mortar (sand, portland cement and water) and Parge the walls.  You can add some "milk" to the batch( the "milk" is a latex additives for adhesion)  to help the parge stick to the walls.   Be sure to wet the walls a bit, it will help the parge stick.   Use a good steel trowel to smooth out the parge for a nice smooth even wall.

" Although I have the right to remain stupid, I try not to abuse that right"

" Although I have the right to remain stupid, I try not to abuse that right"

(post #87799, reply #10 of 16)

Hey John,


     There is a quickcrete product called "quick-wall".   Great stuff. You mix it up, can color it, is fiber filled, and trowel it on.  It looks really great, and is a nice finish look for masonry block, etc.


Re-Home Solutions Inc.

Re-Home Solutions Inc.

(post #87799, reply #11 of 16)

Thanks all. I really did not think that this would generate so many different ideas.

To those suggesting other things than thinset: Next time I use need to do something like this I will use one of the ideas. But this time it is "free" thinset so why spend money? I also have some ugly, but light-colored purple paint that I can use to finish it. Again, free.

(Remember: this is a basement; a man-cave with low ceilings, electrical conduit, heating ducts, water pipes, and tons of messy tools laying around. It is a section where the wife will not even enter unless absolutely necessary. My daughter had a film-making friend who needed a basement to use for an after-civilization-collapse scene; he said it was perfect!)

(post #87799, reply #12 of 16)

I would guess this has been said but in case it has not, Thinset is not a finish material. It is too soft and vulnerable to things like standing water, for instance. It is also more absorbent than other finishes so mold spores could be a problem in a basement, perhaps.



 


I refuse to accept that there are limitations to what we can accomplish.        Pete Draganic


 


Take life as a test and shoot for a better score each day.          Matt Garcia

<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /> 

I refuse to accept that there are limitations to what we can accomplish.        Pete Draganic

 

(post #87799, reply #13 of 16)

Thanks Pete


Just FYI, the walls are dry.  And, there are drywall partitions in the basement that have been there for years without degradation (from water that is; dropped tools can do interesting things).


So, softness does not seem a problem.  As to porosity and spores---hmm...... I think I will do a small portion and see what happens.

(post #87799, reply #14 of 16)

Thinset is behind the tile in most bathrooms (at least when they don't use mastic), and no one has reported mold problems as a result, even though grout is in no way waterproof.

Mold won't grow on masonry (including thinset), unless there is some other material (paint, eg) that supports the mold growth.


As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

(post #87799, reply #15 of 16)

I see Dan H is a big fan of using Thinset as a finished surface.

I think it is a big mistake.

It is not designed for this but certainly I can see the average "home handyman" not understanding that. It looks like cement so it must be the same, right?

It is an adhesive, not a finish product. it is designed to have a surface applied to it... not to be a surface.

FYI, trapped water will cause it to fail under tile. Also, it will not withstand submersion. Not that either is a problem in your application, I assume, but I am illustrating a point on it's durability compared to other options.

It is more porous than other finishes and therefor more susceptible to mold growth. I think Dan mentioned that it doesn't support growth behind tile (he thinks so) but it most certainly can.... however, he also failed to put together the obvious... that the tile is protecting it in most conditions. Degraded tile applications will however allow for mold growth behind the tile... but again this is different that the conditions allowed with thinset as a finish.

Anyhow, that is my two cents. Just because it is free doesn't make it a good idea and I can't tell you how many times this kind of "free" has cost more in the future to repair a problem caused by an "affordable" fix earlier on.



 


I refuse to accept that there are limitations to what we can accomplish.        Pete Draganic


 


Take life as a test and shoot for a better score each day.          Matt Garcia

<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /> 

I refuse to accept that there are limitations to what we can accomplish.        Pete Draganic

 

How is it holding on? (post #87799, reply #16 of 16)

Hi I’m curious to know how it held the test of time.

thanks in advance.