# Tiling over Concrete Expansion Joints



## Clueless

Is it possible (smart?) to tile over expansion joints on a basement concrete floor. They're not moisture prone it seems. My thought was to fill the joints with level quick, then to put red guard over top, then use a membrane additive with the adhesive. Should I be considering this at all? Is there some alternative (short of lining up grout lines with the joints) that could be considered?


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## Clueless

I may have misdefined the joint. I am not necessarily sure it is an expansion joint. However it is a definite 1/4" break line, from one concrete slab to the next. Could it be just a construction joint? How can you tell?


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## ChrWright

If it's a cut of any kind in the concrete you run the risk of slippage & movement that will translate through the grout & possibly even crack the tile (especially with natural stones). Is this newer concrete or old? Has there been any seperation in the joint that you can see?

If the concrete is stable and fully cured--you can tile over this but you need to provide a slip membrane beteen the concrete and the tile. 

Two great products for this are Schluter Ditra (comes in rolls and works very well over concrete) or Laticrete blue 92. 

Go to the schluter website and look at the ditra page. They have a great video that shows the principle behind the product and the installation method.

I'm not sure what you're referring to by "adding a membrane additive to the adhesive". Do you mean a latex additive to the thinset? 

If the concrete isn't stable or the slab is subjected to constant movement and/or changes in moisture (an older house without a perimeter drain for example), then it still might not be advisable to tile over it--even with an isolation membrane.


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## firemike

A less expensive alternative would be to use a Schluter Dilex product and center it right over the control joint. That way, if it does move, you shouldn't have any problems.

Chris brings up some valid questions too. How old is the concrete, what kind of shape is it in, have you done a moisture test yet, does it look like it has moved, how flat is it, is there any type of finish, sealer, etc. The answers to these questions will allow a more accurate answer.


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## thom

Start your layout on the joint. If you have shifting slabs the grout will crack out and you can replace it with the matching caulk.


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## Clueless

It's 4 year old concrete and largely is in good shape. Minor hairline cracks, and relatively level throughout. There appears to be no cracks around the joints themselves. 

I do mean a latex additive to the thinset. Generally the joints look ok, and the floor is in good shape. Just wasn't sure if I wanted to approach this at all.

Is Red guard any good?


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## Flacan

If there hasn't been any movement to this point, odds are that it's stable. 
However, you should never have to guarantee that. 

I can't help you with product, been out of that game for a while.


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## Floordude

Clueless said:


> Is it possible (smart?) to tile over expansion joints on a basement concrete floor. They're not moisture prone it seems. My thought was to fill the joints with level quick, then to put red guard over top, then use a membrane additive with the adhesive. Should I be considering this at all? Is there some alternative (short of lining up grout lines with the joints) that could be considered?




If it were my home, I'd totally skip the tiles, and score the concrete to look like tiles, incorperating the control joint into the design, and then acid stain.

www.acidstain.com
www.scofield.com


















































These are all stained concrete. The cost is much less expensive then tile installation.


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## CCSowner

thom said:


> Start your layout on the joint. If you have shifting slabs the grout will crack out and you can replace it with the matching caulk.


WHAT HE SAID ^


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## reveivl

Neat stuff, Floordude, you should write an essay on that stuff. (And post more pictures!) :thumbsup::thumbsup:


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## Stacy Moran

Clueless said:


> Is it possible (smart?) to tile over expansion joints on a basement concrete floor. They're not moisture prone it seems. My thought was to fill the joints with level quick, then to put red guard over top, then use a membrane additive with the adhesive. Should I be considering this at all? Is there some alternative (short of lining up grout lines with the joints) that could be considered?


They make a joint expansion tape. do not fill expansion with thinset! The expansion is needed...Do not start your grout line their - center off as you should and put the expansion tape on - you can get it on line - or order it from a flooring store - if you do it any other way you WILL get bad results over time that will cause you a rip out job! Dont want that when the tape is cheap - proper - easy to put down.


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## Stacy Moran

*They make expansion tape for this*

They make expansion tape just for this - Order it on line or at a flooring store - any other way will give you bad results over time :thumbup:


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## Bill_Vincent

Expansion tape isn't even close to enough. First, at a minimum, you need a membrane that will cover atleast one full tile on either side of the crack. Several examples would be Laticrete's 9235 (Blue 92), Noble's CIS sheet membrane, Hydroment's Ultraset-- any of those would work. The next thing you need is a movement joint. The only thing the membrane will do is allow you to "move" the movement joint so you can make it fall full tile. Now, you can either use a matching siliconized latex, or, as someone suggested, the Schluter Dilex. Personally I prefer the caulking, only because it blends in andwon't be noticed. In the pictures below, there are 3 such movement joints. See if you can pick them out.




























I'll tell you this much-- all three are from the same floor, and one of the pics has no movement joint in it.


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## CCSowner

I'll bet you your next pay check I can find those joints hahah. 


Bill_Vincent said:


> Expansion tape isn't even close to enough. First, at a minimum, you need a membrane that will cover atleast one full tile on either side of the crack. Several examples would be Laticrete's 9235 (Blue 92), Noble's CIS sheet membrane, Hydroment's Ultraset-- any of those would work. The next thing you need is a movement joint. The only thing the membrane will do is allow you to "move" the movement joint so you can make it fall full tile. Now, you can either use a matching siliconized latex, or, as someone suggested, the Schluter Dilex. Personally I prefer the caulking, only because it blends in andwon't be noticed. In the pictures below, there are 3 such movement joints. See if you can pick them out.
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> I'll tell you this much-- all three are from the same floor, and one of the pics has no movement joint in it.


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## Bill_Vincent

Yeah, but that's because you caulked em!! :no:


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## CCSowner

I know i'm the best caulker there ever was:jester::gunsmilie::boxing:.....I have one question I thought you did some fancy design in the backsplash.


Bill_Vincent said:


> Yeah, but that's because you caulked em!! :no:


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## Bill_Vincent

It's off to the right in the first picture.


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