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-   -   Tile over Painted Lightweight Cement (http://www.diychatroom.com/f5/tile-over-painted-lightweight-cement-114654/)

New_2_DIY 08-19-2011 11:02 PM

Tile over Painted Lightweight Cement
 
Hello DIY and pro people!
I'm new here.
I live in a condo, on the second floor, and under the carpet the floor is painted, and beneath the paint is a layer of concrete (not sure how thick) that has some hairline cracks in it. In a few places, the floor has squeaks (go figure).
We want to put down Porcelain tile, and I've gotten two different answers from tile installers about how it will be done:

Tile guy 1 (Lowes installer... came to our house) says he just needs to "rough up" the paint in order to get the thinset to bond to the floor, and that no backerboard is needed. When I asked about fixing the squeaks, he said that if it were wood, he'd screw it down, but that you can't do that with a layer of concrete. I asked him if he knew why it would be squeaking, he said he did not know.

Tile guy 2 (Newport Carpet & Tile... has not been to our house) says that backerboard is definitely needed because that concrete layer will not properly support the tile. I asked him how he would bond the backboard to the floor, and he said thinset and screws (wouldn't the paint need to come up for that thinset bond to happen?). I did not ask if he would be removing the paint first.

In any case, I've read that no matter what, the paint has to come up in order for the surface to be bondable. Neither party is really telling me what I want to hear, and their price estimates are within $300.00 of each other, even though: the tile is the same price, and Tile guy 1 supposedly has a cheaper install per sq ft price than Tile guy 2, and would not need to purchase and install backboard.
Should I keep looking? I feel like the uppity customer telling them how to do their job if I question their methods.
With tile and install, this will be a $4,500+ purchase for us and we want it done right. We are a bit scared to leap into this magnitude of tile job as a first DIY project (475 sq ft) but we will do the bathrooms ourselves after watching the tile guys do it.

Thanks for any input, much appreciated...
-Nicole

Bud Cline 08-19-2011 11:49 PM

New_2_DIY,

I'm sorry to say that neither of your installer choices so far have any idea what they are talking about. Here's the scoop.

Light weight concrete is common in condos above the first floor. Light weight concrete actually contains gypsum. Gypsum and ceramic tile thinset mortar ARE NOT COMPATIBLE.

One popular lightweight concrete used in condominiums is called Gypcrete sold by the Maxxon Corporation. The product has been around for years and you can contact them to verify what I am telling you.

The concrete (Gypcrete if you will) must have a treatment before any ceramic tile thinset mortar will stay bonded to it for very long.

There are several ways to do this but I'll cut right to the chase.

Oh and by the way...YES...the paint must be removed totally, not just scuffed in this case. Any paint or coating is a known bond-breaker when it comes to ceramic tile thinset adhesion.

Okay cutting to the chase.

In my opinion of all the methods used that will mitigate these issues and insure a successful tile installation is to use a product known as CIS offered by The Noble Corporation.

Noble CIS is a vinyl product used (among other things) as a crack isolation membrane. It is a thick vinyl with a scrim type hairy fabric on both sides so that it can be bonded with thinset. The CIS is applied into a fresh coating of thinset. The tile is then applied using thinset.

The softer/pliable characteristics of the CIS will allow and promote bonding to the gypsum containing concrete product while at the same time isolating the tile installation from the substructure. Even though I can't make any guarantee's I am sure this will also end your squeaks.

I can guarantee you that you never want to apply cement board to a concrete surface. Most all cement boards suffer from quality control issues, they just do. As long as they are being nailed or screwed to a substrate they are great but if they are applied only with an adhesive they cannot be made "plane" (flat) suitably enough to accept ceramic tile.

I don't understand why some guys in this industry that claim to be of a professional status have such a problem knowing the industry. I must apologize for their ignorance of their profession, they give all of us a bad name.

Please keep looking until you find an installer that has this knowledge. Please don't tell them how to do it. For your own protection allow them to tell you how it is supposed to be done correctly.:) What you have been told so far is not correct.

Good Luck.

New_2_DIY 08-20-2011 02:55 AM

Thank you so, so much for the info and company names/resources. The majority of $5,000 is a lot of money to waste on an incorrect job.
I knew the inconsistency in answers mattered. Is there any chance that this surface is anything but gypcrete? Do they do it with Gypsum to make it lighter than regular concrete?
Other than letting him (or her) tell us the correct way they are going to do it, any tips for choosing independent installer, if we end up buying our tile from one source, and getting another to install it?
-Nicole

Bud Cline 08-20-2011 06:42 PM

Actually those type of products are more for fire safety and sound control. Including gypsum could result in a lighter weight product I suppose but I have never researched it. The compressive strength is less than typical concrete I think and that would be because of the gypsum in my thinking.

I do know that installing ceramic tile over those products is problematic and they have always required some special treatment before tile could be installed.

Like everything, improvements have come along over the years so maybe late model multi-level gypsum containing concrete has changed but I don't think so.

Anti-wingnut 08-20-2011 06:49 PM

Just to be clear.

If your building is wood framed and (probably) less than 5 storeys, then gypcrete was used. If the building is taller and/or strictly of concrete construction, or of steel and concrete pan deck construction, the concrete was used in leu of gypcrete.

Other than this little bit of parsing, I would defer to Bud, he is clearly very knowledgeable

rusty baker 08-20-2011 07:04 PM

Everything Bud says is correct. The gypsum is a lot lighter than concrete, so the building construction is cheaper. There is usually 2-3 inches over a 3/4" plywood subfloor, but I have seen the subfloor only 1/2" plywood. The stuff also tends to crack and powder up after 25-30 years. Many times the floors are painted with a white sealer of some sort when installed. It is to extend the life of the floor, as water shortens the life of all gypsum products.

Bud Cline 08-20-2011 08:08 PM

It wouldn't be unusual to have only 3/4" of light weight cement/gypsum product over a sub-deck of only 3/4", IF the deflection of the floor structure does not exceed 1/360.

Different sub-structure techniques and configurations require different thicknesses of light weight product.

I don't know how we got off the beaten-path but it seems we did.:)

By the way...the surface cracking could be from deflection but it could also simply be from surface tension. In my experience surface cracking is a frequent occurrence in those modified products.:)

Anti-wingnut 08-20-2011 08:30 PM

Quote:

Originally Posted by Bud Cline (Post 711815)
By the way...the surface cracking could be from defection but it could also simply be from surface tension. In my experience surface cracking is a frequent occurrence in those modified products.:)

After having seen acres of gypcrete poured over the years, I would think it is very likely for the crews to add too much water to the mix, which would result in a greater portion of the admixture drying by evaporation than by curing. This would also result in cracking.

Wether the pour was 3/4" or closer to 2" could also be a function of it necessity. If it is required for fire rating, it must be much thicker than if the architect only needs it as a floor leveler

BlueStoneFloors 08-22-2011 10:01 AM

Quote:

Originally Posted by New_2_DIY (Post 711166)
I asked him how he would bond the backboard to the floor, and he said thinset and screws

LOL...screw to the gycrete? Am I missing something :laughing: What a hack... FYI: Noble CIS is an awesome product, is there anything about flooring that you don't know, Bud?

rusty baker 08-22-2011 12:33 PM

Quote:

Originally Posted by BlueStoneFloors (Post 712687)
LOL...screw to the gycrete? Am I missing something :laughing: What a hack... FYI: Noble CIS is an awesome product, is there anything about flooring that you don't know, Bud?

He doesn't know how to retire. :laughing:

oh'mike 08-22-2011 04:51 PM

He floored a lot of folk with his tongue and his quick wit!!!!:laughing:

Bud Cline 08-22-2011 05:11 PM

Trying to find the comment about screwing to the Gypcrete but I'm not seeing it anywhere. I must have missed it reading too fast.

What I did find in Post #1 was:
"When I asked about fixing the squeaks, he said that if it were wood, he'd screw it down, but that you can't do that with a layer of concrete."

That statement is correct.

Not here to win any popularity contest, what you see is what you get.:)

"Not here for a long time, just here for a good time." - song lyrics from something.

Bud Cline 08-22-2011 05:24 PM

Okay I found it !


Quote:

Tile guy 2 (Newport Carpet & Tile... has not been to our house) says that backerboard is definitely needed because that concrete layer will not properly support the tile. I asked him how he would bond the backboard to the floor, and he said thinset and screws
Turn and run away from that guy as fast as you can, he has no idea what he is doing and will only create additional problems for you trying to use that method. Run, run away, run fast.:)

New_2_DIY 08-23-2011 06:19 PM

Quote:

Originally Posted by Bud Cline
Okay I found it !

Turn and run away from that guy as fast as you can, he has no idea what he is doing and will only create additional problems for you trying to use that method. Run, run away, run fast.:)

LOL!
I will run fast for sure! The search goes on, I guess. Thank you all for the info. Very helpful place to be! There is much conflicting info out on the web, nice to be walking on solid ground here (heh)

New_2_DIY 08-24-2011 01:28 AM

Quote:

Originally Posted by BlueStoneFloors

LOL...screw to the gycrete? Am I missing something :laughing: What a hack... FYI: Noble CIS is an awesome product, is there anything about flooring that you don't know, Bud?

I looked on their website, never knew about underlayments. I have much to learn, came to the right place!


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