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I've got about 600 sq. ft. to lay in Travertine over 9 yr. old concrete slab. The original slab is a mess. There is some old skim coat that buckled and will need to run some levelquick to solve that problem. What concerns me is the cracking. There are cracks ranging from hairline to 1/4 inch criss-crossing the floor. It looks like both products will prevent the stone from cracking. The tiles are going to be 18 x 18. Which product will be the most cost efficient? I need to submit a change order to correct this damage. (We just pulled the flooded out Pergo and found this underneath.) Ditra looks better but RedGuard may be quicker. I've never used either product. Any suggestions?
 

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I wouldn't compare redgard to ditra. Hands down, ditra is the better way to go for crack isolation membrane.

You have some pretty serious cracks in that floor and I'm wondering if it should be tiled at all. Keep in mind that neither product will do any good if those cracks are vertical (one side of the crack is higher than the other). If thats the case, you need to use something other than ceramic tile or stone as your flooring.
 

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Both Ditra and Red Guard are for preventing tiles for cracking
NOT to fix existing cracks in substrate.

If the cracks are out of plane then you can't tile.
You basically are lacking expansion joints.

If the cracks are in-plane, you CAN tile.

Any pictures?
we all like pictures
 

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Discussion Starter #4
Cracks in plane

Fortunately, all the cracks are in plane. I can only speculate that it was improper mixing of the skim coat by a prior contractor (now out of business) and high moisture in the slab that caused the skim to buckle and crumble the way it did. I had never seen anything like that before. It was like somone had blown up a balloon under it. What a mess ... mold, yuck. One of my guys suggested laying down 1/4" hardi board to prevent the existing cracks from transferring up through the tile. I started doing some research and came up with the RedGuard and Ditra products due to the waterproofing properties.
I'll be the third contractor to lay a floor in this house in 9 years. I do not want callbacks. I'd rather deal with the moisture issue, give them a low maintenance floor and add them to my reference list. (Ok - that and they have a big scale cabinet job thrown in with this.) :w00t:We've got too many half baked wanna be "professionals" in Atlanta. I'm getting tired of cleaning up after these guys who send in illegals to slap a job together and run. Sorry ... had to vent. :furious:
I'll see if I can get my girl over there Saturday to take some pics. I've also got to source out the Ditra. Have y'all had better luck buying local or online? Thanks!
 

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They don't sell Ditra at Home Depot near you?
We get it here at good ol Home Cheapo
 

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Moisture in slab

Where is the high moisture coming from? Red Guard or any applied membrane will not stop moisture from entering from below. They only stop moisture from entering from the top side.
Sounds like you need to correct the moisture problem before you install.
Call the manufacturers to get there input on it.
Jim
 

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Trav,

JJC is correct. Neither DITRA nor RedGard is the product to use on that substrate, you'll be back there standing good for another failure. If moisture is ever-present then you CAN NOT seal it in by covering it with any membrane.

You might think about correcting the substrate with LevelQuick throughout and tiling on that. This way - the floor will still have an opprotunity to breathe and the natural evaporation process can still be available.

Actually the travertine along with the grout lines will aid the evaporation process, the problem is going to be a possible discoloration of the travertine due to the presence of constant moisture. Another thing to be seriously considered is that the travertine should be sealed before it is grouted and sealing the travertine under these conditions could also be problematic for you in the near future. I suspect the sealer will release in a short time creating more problems for you and the owner.

I'm thinking the only possible salvation here is to use glazed ceramic, it won't have to be sealed and it will still allow evaporation through the grout joints.

The first thing I would do would be to take some moisture readings and see exactly what the moisture content really is before speculating any further. Is the moisture a year-round issue and if yes, why? Where is the moisture coming from?:)
 

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Trav...three contractor in nine years and your replacing a floor that has been damaged by water..break the news to the customer that the house has some problems that need to be addressed regarding moisture and the lack of moisture containment and removal. ie weeping tile, sump pump, rain gutters. You will never be able to warranty the work for more the the time it takes you to leave with the cheque. Why bother with the expensive underlayment just dump in some concrete and throw the tile on the floor at ramdom it is going to be taken up again anyway....
 

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Just spoke to my Schluter rep who told me that Ditra provides complete crack isolation, and waterproofing from above AND below.
 

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May I suggest ECB membrane?

Although Detra and RedGuard are fine products, I personally was directed to a sheet applied crack isolation product called ECB membrane by NAC Products. I layed it over an existing slab with moisture and crack problems about a year ago and have not had 1 problem. This product handles 10# of moisture coming through the slab and can handle up to 3/8" movement in the slab. I was impressed with that and that there was no waiting time to install my tile over top of it. There website is nacproducts.com.
 

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NickD1882,
Your correct that NAC does put a good membrane, but it will fail when the moisture comes from the slab. As with all membranes, they stop the water from getting into the slab on top. I still stand with my original statement that he needs to fix the cause of the moisture getting into the slab from below before any money is spent putting in a new floor. Bud is also correct that the travertine will allow moisture to escape but it will be slow and thats saying that the tile is bonded directly to the slab. Travertine is soft and porous so it will act as a sponge and will only give up moisture when the air is drier that the stone. If you have never experienced a travertine floor that holds water or moisture, then you are missing the "smell of a lifetime":w00t:. Another thing is the efflorescence from the moisture rising up through everything and being deposited on the surface which will cause the homeowner enough concern to stop payment on that check.
Bottom line is still fix the cause before installing anything.
 

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JJC,
Their literature and testing suggests their membrane handles up to 10# of moisture vapor pressure. Are you talking more then that?
 

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NickD1882,
What you are mentioning is from the top trying to pass thru and I don't question that. What I am saying is if the water source is from the bottom, then NAC says.... if the slab is moist or has hydrostatic pressure then don't use it. When the moisture rises it can and has been known to release the glue holding it in place. That's the same principle as "the slab has to be free of bond breakers", such as sealers, paint over spray, and moisture etc.
 

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You say the existing patch, blew up and you never seen anything like it.

Sure sounds like a gypsum based concrete floor, especially how you described it cracking. Portland cement over gypsum, does exactly what your describing, as far as the blowing off the gypsum.
 

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Floor Moisture and Installing Tile

Agree with last post.. possible it is "gypcrete" which is portland cement/ gypsum combination used in some construction projects. Known to fail under stress or water conditions.

Whatever the base surface where is the water/moisture coming from is the root questions and necessary to know / monitor/ control if possible.
Without answering / addressing that issue failure is pretty much guaranteed.

I have / my crews / used red guard.. and floor isolation membranes... great products for crack isolation.. but not a fix for a buckled substate.

Ive seen underground stone/ slate "spall" and heave concrete floors up over 4-6 inches...

Is the substrate/ on ground or over structure?
 

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I personally was directed to a sheet applied crack isolation product called ECB membrane......
ECB is a roofing membrane that has been discussed many times on these forums. It is not suitable for a tile installation membrane. It has been tested and has failed miserably. You won't find the use of ECB in any of the tile installation manuals or guidebooks. It is not blessed by the TCNA and you won't find it listed as a tile membrane in any of the ANSI Standards.:)
 
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