# Thoroseal or Latex coating over a block wall?



## Python49 (Jun 21, 2011)

If I were to try to use a latex coating to cover block lines on the exterior of the wall and don't like how it came out, is it still going to be no problem to just stucco over it? 

Also, is anyone familiar with Thoroseal which is a cement based coating agent? Will this be thick enough to cover up the joints so that they are not visible? Am basically trying to explore options for covering up block joints/lines so it can be painted and look decent without spending as much to stucco.


----------



## superseal (Feb 4, 2009)

You'll be wiring it up with lath if you don't like the latex, and yes, Thoroseal is a high build product and would cover many sins, but I would flush out the joints first with mortar mix or equiv., allow to cure and then Thoro. Tampico brush application works best - min. two coats.


----------



## dakzaag (Jan 6, 2009)

Thoroseal is a great product, but I think you are expecting it to preform a little too well if you think it will hide the mortar joints on a block wall.

Even two coats will probably still leave some shadows. 

If you try to fill the joints, you had better cut them out first or the thin layer of mortar will probably fall off and take the Thoroseal with it.


----------



## Tscarborough (Feb 25, 2006)

Thoroseal is a great product, but it is a coating, and as such will mirror whatever is under it.


----------



## Python49 (Jun 21, 2011)

forgot to mention that I'm referring to a block wall where the joints have been flushed with the block


----------



## superseal (Feb 4, 2009)

Python49 said:


> forgot to mention that I'm referring to a block wall where the joints have been flushed with the block


I use a ton of thoro and have for many years...My main supplier is Thorosystems out of Folcroft, PA and is minutes from my shop. I have unlimited access to company reps and am personal friends with the owner. Thoroseal, t-coat or t-lastic would be a fine choice of materials. Other companies make products for block which are high build such as block fillers and such. Take my word for it, any of the above thoro's are a fine choice to clean up a wall.


----------



## Rockmonster (Nov 15, 2007)

If the joints have been flushed to the wall, and some time has passed, you will have more success with *whatever* product you use to hide the joints. Thoro makes some great products, Thoroseal being one of them as superseal mentions. I'm not sure what latex coating you're talking about, but going over_ that_ will most likely be a problem if it doesn't do what you want. Silpro Concrete finish is also very good.....Sonneborn has a great lineup as well...You should be able to find some cementitious product that does exactly what you need it to do.


----------



## Python49 (Jun 21, 2011)

hey, when you say going over that should be a problem, do you mean stucco'ing over it? we should have experimented with it on the inside since that was going to be sheetrocked over anyway and the outside wall is being stucco'd. I just wanted to make sure that the test we did doesn't prevent stucco from bonding to the wall. it was some kind of product we got at lowes that was latex based and used for coating a wall, the product listed that it can be used for the exterior of a concrete block wall


----------



## parkers5150 (Dec 5, 2008)

thoroseal is a waterproofing coating that ia a two coat app. and not cheap. why wouldn't you just mix up some more spec mix (mortar mix) cover wall and sponge trowel ??


----------



## Python49 (Jun 21, 2011)

well, i hadnt yet looked into the price but I was under the impression that the cost of applying thoroseal would be less expensive overall since it would possibly negate labor costs (presuming its a DIY ordeal?). Since labor is the most expensive part of stucco'ing I was looking for ways to just cover up the exterior of the concrete block wall without needing to stucco


----------



## Rockmonster (Nov 15, 2007)

So you have already gone over the exterior of the wall with the latex stuff? Or was it latex _modified_ (cementitious product)? And if so, did it do what you wanted? Now let's assume you didn't. You can use Thoroseal, that is certainly a DIY product with a professional cost. I mix 50/50 water/latex admix with it and brush it on with like a wallpaper brush, those thick yellowish ones....but it is a coating, and joints will often telegraph through, especially if done very recently. Since you said your joints were flushed, I would use Silpro concrete finish.....that will trowel on roughly 3/32" or less.......flat as you can, and then sponge it. That will usually cover those joints nicely......you will use an admix with this as well....But I have to admit, I'm a little confused. One place you say you wanted to avoid stucco, and another you said the outside is being stuccoed....?


----------



## natural1 (Aug 30, 2007)

Another option would be to use sure-coat or surface bonding cement. It's a fiberglass reinforced cement typically used for block wall construction without mortar joints. Also, has water proofing characteristics. 
I think the coverage is about 40 sq. ft. per bag at about 16 dollars a bag. Not the prettiest finish. Comes in white and grey but I guess you could add color to the white.
It is trowel applied and requires some technique to give a smooth finish.


----------



## Python49 (Jun 21, 2011)

Rockmonster said:


> So you have already gone over the exterior of the wall with the latex stuff? Or was it latex _modified_ (cementitious product)? And if so, did it do what you wanted? Now let's assume you didn't. You can use Thoroseal, that is certainly a DIY product with a professional cost. I mix 50/50 water/latex admix with it and brush it on with like a wallpaper brush, those thick yellowish ones....but it is a coating, and joints will often telegraph through, especially if done very recently. Since you said your joints were flushed, I would use Silpro concrete finish.....that will trowel on roughly 3/32" or less.......flat as you can, and then sponge it. That will usually cover those joints nicely......you will use an admix with this as well....But I have to admit, I'm a little confused. One place you say you wanted to avoid stucco, and another you said the outside is being stuccoed....?


Oh, sorry for the confusing explanation. The current block house we were planning to have stucco'd, but prior to stucco'ing it we were testing out this latex coating to see how it would look since we figured we'd just stucco over it anyway. That's why I was asking if having applied that would cause any problems with stucco'ing. 

We are looking for something that can just cover the block/joint lines and that can be applied with DIY to cut down on costs. We didn't think it was necessary to spend so much money on stucco when really all we wanted was a flat/plum wall that we could paint. 

Is Thoroseal more of a DIY product than Silpro? Essentially would like something that is very simple to sort of paint on or apply 2 coats.


----------



## Python49 (Jun 21, 2011)

bump for follow up info/responses


----------



## JD3lta (Nov 22, 2009)

I remember a painted block wall on an outside of a MC Donald's.. And I recall it was funny how thick the paint was, years of maintenance just created this thick paint.. And the joints were still visible.. A veneer or stucco seems the most practical in my opinion.


----------



## CJKarl (Nov 21, 2006)

I'n my opinion you would have to foam or wire over the block to make the joints completely disappear. I have seen pretty good stucco jobs that look like crap as soon as there is a quick change in air temp.


----------



## Supahflid (Mar 22, 2011)

BASF issues specific instructions for applying Thoroseal over c.m.u. and those instructions involve a base coat that once applied, will have to cure for about a week. Thoroseal Plaster Mix is then applied over that. Sounds pretty extensive to me. I can tell you that any coating, be it cementitious or acrylic or whatever, applied in a thin film will allow the joints to telegraph. I think the materials are fairly inexpensive and the labor is not too bad, but it's more involved than just slapping some coating on the wall and letting the rough end drag.


----------



## Python49 (Jun 21, 2011)

hey guys, i applied the thoroseal over the block and it definitely did the trick of covering the joints. my only question now would be, what's the difference between this and plaster/mortar/stucco? It felt and looked similar, but since I've never done any plaster myself I didn't really have anything to compare it to. Thoroseal is more expensive than bags of mortar/cement, so just was wondering what it offers that those don't?


----------

