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kristen4hair 02-24-2009 11:31 PM

Underlayment for tiling over stained concrete?
We have used a grinder on our entire concrete foundation, patched with Cementall, then stained two of the rooms with many layers of Behr solid color stain and high gloss sealer. Then decided we want to get the tile we always wanted, instead. Do we HAVE to sand off all the stain before laying a membrane? Do we have to lay a membrane? And is there something other than Ditra (sp?) that can be used effectively for the underlayment? The Home Depot guy said I can use vinyl sheet flooring, but I just read a bunch of posts that say no way. The Ditra is so pricey!

JazMan 02-25-2009 02:25 PM


No matter what you would like to bond to the slab, you will have to remove the sealer at least, maybe the stain too. Once the floor absorbs water when tested, you should be OK. More on that once you grind the floor.

Installing Ditra is a good idea. You think it's too expensive? Well, it's not cheap, but how much are the tiles? If you go with cheap tiles, that'll make Ditra seem high for sure. How large an area? Describe the condition of your slab. Is this on grade or below grade? Cracks, moisture?

You will learn not to ask questions at HD, aren't there any real tile shops near you?


kristen4hair 02-25-2009 06:44 PM

Hi Jaz, I grinded 1200 sf of slab before starting the staining process, so I guess I was looking for any way to avoid doing that again.

Now, If Ditra is the same thing as the 'anti-fracture membrane' we were quoted on, it was a big chunk of our budget.

I realized that I assumed the membrane and Ditra are one in the same. We are looking at the less expensive ceramics, as our budget is $3000 for those 1200 sf. Is that completely unrealistic?

I'm sorry, I don't know what on grade or below grade means! Our foundation seems very level, with lots of holes from tack strip nails and quite a few long cracks that I patched with CementAll.

I left some of the cracks alone, mainly in the powder room, because they looked cool. I really don't want to be stupid about this and won't do the tile yet if I can't do it properly with our little budget, but the way I chose to stain the concrete is just way too time consuming for something that's not turning out reeeaaally nice. Thanks for your advice! Kristen

PS We have tile stores nearby, the slab is 17 yrs old, and available credit at HD! :huh: And it's level with the yard and that the grade? Moisture not an issue. I could go on forever....jeez

JazMan 02-25-2009 08:01 PM

How did you come up with a figure of $3,000? Why not $2,900 or $3,300?

Weren't you told what brand of membrane you were pricing? Ditra is an uncoupling membrane, I really like it. However Ditra costs more than cheap tiles. Usually if you choose cheap tiles, you don't bother with membranes. There are other membranes and other cheaper methods though.

Patching the cracks is a waste of time when installing tile. Are they in "plane" or is one side of the crack higher than the other? Ground level is on grade. How do you know moisture isn't an issue? Are you on a slight slope?


kristen4hair 02-25-2009 08:24 PM

3000 is the amount available on our home depot card! We're really stretched thin with all the unexpected (we expected this) challenges since moving in.

I patched the cracks because I was staining. They still show but are more subtle. They are level cracks. Plane.

The moisture thing....I thought that was related to weather and grade. Making stuff up in my head again? The front yard does slope down, and the back is level with a slope all the way at the back. There is an in ground pool.
We're in Southern California, and except for a few days of rain this winter, it's a beautiful day every day!

Does cheap in price always mean cheap in quality? As far as the membrane, it only said anti-fracture membrane on our quote, no brand. It was 6 months ago, but usually I'll remember stuff like that.

Sure appreciate your time.

JazMan 02-25-2009 09:00 PM

You certainly have to address the cracks. There are dozens of membranes. I think Ditra is the best and also does more than just help with cracks. Also manages moisture.

There are also crack suppression thinset mortars that can give a little for expansion. In addition you will need expansion joints all around the perimeter, around any vertical objects and you have to make joints in the field.

Thanks for the weather rub-in.....ahhhhhh report.:laughing:


kristen4hair 02-25-2009 09:14 PM

Would you use the crack suppression thinset without a membrane? Just put it on the concrete?

I am afraid to ask about expansion joints at hd. No idea what they are. What should I expect to pay for whatever units they are sold in?

What is it, like, 100 below zero there?:laughing:

And how does one put joints in one's field? I am waaaay more ignorant than I thought.

JazMan 02-25-2009 09:46 PM

It was actually warmer today, hit 42 and rain. Has been a colder than normal year.

Ask those people at your own risk. Most are nice people, they just don't know anything about flooring, especially tile. They will not hire you if you know how tile is sold, installed etc.

Those thinsets are used instead of membranes. They are not as good, but they are cheaper. You will find out 5-10 years later.

If you buy at HD, they will probably carry Custom Building products brands? Their Flexbond is supposed to cover cracks up to 1/16". That is not much but? Some other high end mortar can isolate up to 1/8".

Does your slab now have any expansion joints or cold joints in the field? Or is the slab all one continuous pour? Does the floor get sunlight for any length of time? Where the field joints go depends on several factors including the measurements, and layout.


yesitsconcrete 02-26-2009 06:02 AM

don't feel alone, embarrassed, or think you're stupid,,, you ask serious questions out of ignorance &, thankfully, there's a cure for that - its stupid that's fatal - we're all ignorant about something, fergawdsake.

don't expect experienced technical answers from anyone wearing an apron - they'll be hustling the hot dog stand tomorrow OR watering plants,,, you'll get more outta this forum than anywhere else - just be sure to post your comments using words we use to be certain we're all communicating.

btw, running a walk-behind dble-head'd grinder'll be much faster than anything else,,, use the hand grinder for edging after removing any baseboard,,, hook the dust shroud up to your wet/dry vac.

forming a budget according to the available credit remaining in one's account is often fatal.

good luck ! ! !

'bailout'-is-a-four-letter-word ! ! !

ccarlisle 02-26-2009 09:02 AM

You say you have 1200 sqft and a budget of $ Ditra may be "out" at $2 per sq ft. But although most installation methods on concrete call for some sort of membrane to prevent cracks from telegraphing through to your tiles, you may be able to get by without it.

Please remember that the only thing many professionals have to "sell" is their reputation and many will not tell you something they wouldn't bet that on; reputations are precious, hard to get and easily broken and none of us like to fix something that is broken, especially if we did it. So you'll normally get quite acceptable advice. But "acceptable" is in the eye of the beholder...

And what may be 'acceptable' to you in terms of longevity of the job or the appearance of cracks may not be to us. And vice versa. So realistically, here you may be constrained (by your budget) to sticking the tiles down with thinset. But by using a thinset-only method, you may have what we call a failure in who-knows-how-long...six months? 5 years? however long it is it will be longer than anyone would warranty - because we don't know. Nor do the associations know, the associations who publish standards for you're basically on your own.:yes:

Having said all that, there are manufacturers of tiling systems that make a number of their products available for similar installations. I mean your situation is hardly unique, is it? So if you search out these companies they may have a method for you, provided you follow some admittedly stringent guidelines and have the exact substrate needed for their systems. Then -and only maybe - then, you'll get some sort of reassurance that you'll not be doing the same installation in a few months without as a much as a 'sorry' from anyone.

But without fail, any manufacturer of any such system will require that the surface of the concrete be as clean as possible and by that they mean no paint, no sealers, no dust, no satins or other chemicals. So, I think you're looking at grinding the concrete.:(

yesitsconcrete 02-26-2009 09:33 AM

what do you guys think about kristen using hardi-backer as tile underlayment along w/LOTS of conc screws ? ? ? we use it for installing seamless conc flooring over conc or wood AFTER jnt/crk treatments sometimes incorporating expand'd wire mesh.

that being said, many h/o's-diy-ers choose behr 'cause its the only stuff avail to them & they're watch'd too much tv :yes: then they have trouble - LOTS of trouble :censored: & find the ' customer svce ' people used to work in apron stores :laughing: if they chose kemiko or h & c (sher-wms), they also have trouble,,, i know of no pro ( painters aren't acid-staining pro's ) who'd choose the 1st or last altho some do use the middle & succeed eventually AFTER they learn the process which's much more involv'd than indicated on the label,,, those're probably the same diy-ers who use qc come to think of it :whistling2:

' bailout '-is-a-four-letter-word

kristen4hair 02-26-2009 10:39 AM

Yes, I really want to do the job right so we don't have "failures" later...or sooner. It looks like it would be best to find some way to expand our budget so we can get decent materials. If we can take care of the installation ourselves, the investment will be well worth it.

The neighborhood and house value don't warrant going all out, and we're not here permanently, so resale is a big consideration when choosing what to use for floors, cabinets, etc.... When we were house shopping, the amount of mickey mouse DIY projects we saw was staggering. Such a turn-off!

So...I will check out the more specialized tile stores in my area, grind out the @#$%! stain I applied, definitely use a membrane of some sort, and ignore the apron guy.

Just a note about the behr sealer...after 3 coats-24 hrs in between-1 week later-stuff that got on the floor soaked right in and left spots that won't come out. I did everything by manufacturers instructions. Also had some bubbling that just peeled right off. I grinded, scrubbed, rinsed, rinsed again, primered, and waited longer than minimum drying time in between all the coats. So frustrating! But I'm done with that. Live and learn...
And listen to the pros!!!!!

yesitsconcrete 02-26-2009 10:51 AM

attagirl,,, as a friend of mine says, ' if we don't have the time to do it right the 1st time, where in ****'re we going to find time to do it over ? ? ? '

you wouldn't be able to grind off REAL stain as the acid attacks the concrete's free lime & prepares it for coloring from the mineral salts,,, that being said, behr ain't :no: so all you need to is remove the sealer ( water-based ? ? ? )

we use solvent sealers - 2 coats diluted 1:1 w/xylene - apply 1st coat, wait 1/2hr, apply 2nd coat, collect check :yes: & leave,,, was a moisture test prior to prep & stain done ? ? ? also, suspect floor wasn't prep'd correctly,,, can't learn this stuff from watching tv, surfing websites, reading labels, or ducking into forums, kris, but that's closing the barn door after the horse's gone :huh: its really a good item despite your experience,,, just that not everything's a silver bullet ! ! !

kristen4hair 02-26-2009 10:56 AM

Jazman, I just saw your post. The slab is one continuous pour, and we get a lot of sun all afternoon.
I WILL do this project properly. Just need to get the best deal possible on the good materials.
The husband and I really want our downstairs living space, well, livable, but we will take our time pricing materials and gathering info.
Sounds like you're getting some tolerable temperatures! It didn't get past 65 here yesterday...BRRRRR.

kristen4hair 02-26-2009 11:12 AM

No moisture test, and I suspected moisture was an issue -- after I said moisture isn't an issue -- when I saw the bubbling. It was over a couple of the cement-all patches, mostly. I used a wipe on/wipe off technique with different colors of solid color stain...a neat look. The time it's taken to do less than half the floor is just not worth it, though.

The sealer is water based. I have a unused 5 gallon bucket to return... a little more $ for the tile job!

I read several articles & posts about prepping the concrete, but guess I didn't read the one that mattered!

So I can use a sander on the sealed stained areas? Instead of a grinder? Still so messy, and I don't know why I like the idea of sanding better, as it really is the same amount of work. I was just so happy to return that grinder to the rental place and say 'I'm done!'.

Thanks for your input. :)

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