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Jun 25, 2011
, AZ
One of the latest emails I get from people.

Dear Mr. Floorsavior,

I have been scouring websites looking for information about leveling our horribly uneven gypcrete floor and came upon your postings. We're in Maryland and are having a terrible time trying to get a straight answer from local concrete and Ardex companies. So, in total desperation, I'm hoping you will generously share your advice with us.

When we pulled up carpeting last year off our at-grade concrete slab (first floor, not a basement), it confirmed that the slab was very uneven. We contracted with a (supposedly) reputable company to even off the concrete and install an engineered wood floor. After less than 6 months, it became apparent that the floor was still extremely uneven, but now in different places. So, we ripped out the wood, which was seriously bouncing in all the areas that dipped.

We just found out that the installers tried to even the floor using gypcrete and we're sure that no bonding material was applied to the concrete slab before the gypcrete was poured. The surface is so soft that it's reduced to powder merely by walking on it. One concrete installer suggested cleaning off the loose material, applying a bonding agent/primer, and then applying a self-leveling material, Duraamen Pentimento. Another suggested using Ardex p-51 to prime and then leveling with Ardex gs-4 because anything stronger might "pull up" the weaker gypcrete. Another suggested using Ardex p-51 to prime and Ardex v-1200 underlayment. (I'm concerned about v-1200 because the specs the company sent to me said not to install it on gypsum, though I don't know if that's the same as gypcrete.)
We've already lost a fortune on a defective concrete installation and flooring. Any advice, or any other locations/postings that you could point us to, would be VERY welcome!! Thank you!
Are you going to the site?

I wish, but they are tapped out and live in Maryland or some where like that. What do you think of the installers fix? I feel it needs a complete demo. I'm not a fan of gypcrete on concrete at all.
I don't know much about this product but reading some material on the web, it appears to be a common problem.

By Shawn Maciewicz, House of Floors, Inc.

Gypcrete floors have great benefits to reducing costs during the construction phase, however host a multitude of problems later on in the life of the building. If your building was built using lightweight gypcrete on the second and third floors, then you will run into a few problems when trying to upgrade to ceramic tile. Firstly- re-pouring gypcrete can be very costly from a labor standpoint. Secondly- after time, gypcrete will start to crumble turning into a very fine dust-like particulate. Before you upgrade to ceramic tile, you will want to remove the existing flooring, whether that be vinyl or VCT, and during this process the gypcrete will start to crumble, and also come up in large chunks. This is where it is very important to follow the fire code. FIRE CODE says you MUST replace it using at equal or better material within the guidelines of the code. The material that you use must have a minimum of a 1-hour fire barrier, so you have a few options. Obviously your first option is to hire a subfloor expert to come and re-pour gypcrete in the damaged areas. This option tends to be very costly and time consuming. In addition we have found that in most cases even when gypcrete is re-poured correctly, and ceramic tile is installed directly over the new gypcrete, it does not take long for the gypcrete substrate to start to deteriorate. We have seen ceramic tiles start cracking and have a very hollow sound as quickly as 6 months after being installed. This result is from the gypcrete being compacted, or impacted by a hard floor such as ceramic and tends to break down into a dust underneath the tile which results in a hollow sound that will eventually lead to cracking tiles.
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By Shawn Maciewicz, House of Floors, Inc.
...ceramic tiles start cracking and have a very hollow sound as quickly as 6 months after being installed. This result is from the gypcrete being compacted, or impacted by a hard floor such as ceramic and tends to break down into a dust underneath the tile...

havasu didn't provide an article link so I'm not readily sure of Mr. Maciewicz's qualifications but his explanation seems to me to be specious.

The reference doesn't really apply to the Maryland homeowners' situation as their subfloor is "at" (on-grade) concrete that was most likely, in an attempt to cut corners, covered with an over-watered gypsum floor & wall patch that has deteriorated.

The surface is so soft that it's reduced to powder merely by walking on it.

Going over this with anything would probably be another mistake. It simply should come out and the substrate should then be professionally accessed to determine what it needs to make it suitable for the intended floorcovering.

In the case of bonding to gypsum with portland cement this CTIOA report explains much. Pay particular attention to ettringite about 3/4 of the way down. I think gypsum sub-floors get a bad rap mainly by the people that don't cover them properly.
The gypsum product MUST be removed in its entirety before anything can move forward. There is no method recognized by the industry for working with the product in its present condition. What was done previously would not be the measures that should have been taken at that time. Bad uninformed idea from the git-go.
"MUST" presents some sort of obligation but in reality finances often dictate or compel the course of action; not what the floor covering industry recognizes. The matter-of-fact is I think a number of flattening options open up if the homeowners were to use a floating floor covering.
I also suspected that it wasn't actually "Gypcrete" but more likely watered down white patch. I've seen and covered hundreds of thousands of s/y of Gypcrete with glue down carpet, carpet tiles, vct and some sheet goods.

it's a HORRIBLE, HORRIBLE product that isn't suitable for most commercial situations

I don't know of any residential applications other than apartments and elderly housing that I've seen-------what I mean is I can't imagine Gypcrete in a single family home on grade concrete.

Whether it's actually Gypcrete or just watered down white patch my advice is to grind it, chip it, sand it off down to the slab and start over

that crap has no place in my world
Incognito said:
it's a HORRIBLE, HORRIBLE product...

I think it performs quite well for what it was designed for. Albeit it's not fun to install on, but what is. It usually requires quite a bit of prep and prep = income = good.