Crack Mitigation Membrane

[ralphi]

Many use crack mitigation membrane between the bare slabs and the tiles. But if the floor deflect.. won't the tiles crack? I know the crack mitigation membrane is to avoid any cracks from the tiles from affecting the slab itself. But if the slabs themselves deflect, what prevents the tiles from deflecting and cracking? How do you usually put tiles? Thanks.

 

[bowlingdanish]

I've not heard of those, but that's neat. Does it bond to the tiles and not the concrete?

Concrete typically cracks due to shrinkage, so it's all about the slab trying to get smaller but being restrained by things. If the slab deflects vertically, then yes the membrane won't be any help at all. rip tiles.

 

[Ron]

Crack mitigation membranes are intended to mitigate cracking that occurs from drying shrinkage of the concrete below. They are not intended to mitigate deflection cracking, though they might to some degree. Keep in mind that deflection of the slab is more likely to induce compression in the tile, thus cause buckling or "tenting" of the tiles.

 

[ralphi]

So how do you guys put tiles on slabs that can deflect (spans that are not short)?

 

[Ron]

Use "soft" joints at regular intervals (substitute compressible sealant for grout).

 

[ralphi]

can the tile "soft" joints just be 0.078" to 0.12" (or 2-3mm) gap in between tile? This is enough to cushion from any magnitude of deflection of the flooring?

 

[jdgengineer]

In addition to above, the floor should be designed for minimum deflection limits set by Tile Council of America or Marble Institute of America depending on type of tile to be installed. On concrete, I believe both limit total deflection to L/360. For wood framing Marble Institute revises this limit to L/720.

 

[Ron]

ralphi...as jdgengineer notes, you have to limit the deflections as noted. Soft joints should be the same width as the grout joints. If you have to place them more often, so be it.

 

[ralphi]

Guys. If you put marble or terrazzo directly over bare slab.. and walk over it.. you can feel the marble feel hollow.. but if you put let's say crack mitigation membrane and thinset tile adhesive between bare slab and marble/terrazzo.. would you no longer feel any hollowness? (for those who have actually tried it)

 

[hokie66]

I don't know about the membrane. Is it a sheet membrane or is it more like flexible tile adhesive?

If tiles, marble, terrazzo feel hollow or drummy, they are not adhered to the slab. You don't feel the hollow sound if the adhesive is intact. Drummy tiles are fairly common if control joints have not been placed close enough together, and the necessary spacing will vary with the interior climatic conditions.

 

[ralphi]

Any kinds of crack mitigation membranes as I haven't used any of these yet.

How many years after fresh slabs placed that no shrinkage occurs anymore. For example. In old 5 years old building.. do you still need to put crack mitigation membrane if you have to start putting tiles on the slabs (where it has been bare for 5 years or just vinyl put with thin paste that would be removed)??

 

[hokie66]

There is no definite answer to your question. It is always best to use best practice available when installing floor tiles.

 

[Ron]

Agree with hokie66....a hollow sound means poor bond. If the bond is poor, even over a crack mitigation membrane, you will hear some level of sound change between good and bad.

Drying shrinkage occurs over an indefinite period. As hokie66 notes, changes in interior environment conditions will change the conditions of shrinkage. Adding a crack mitigation membrane usually slows shrinkage because it keeps the slab from drying at a faster rate. Shrinkage still occurs, just at a slower rate. The crack mitigation membrane moderates the horizontal shear between the slab and the thinset. If you use a flexible tile adhesive, you won't need a mitigation membrane. Flexible tile adhesives are not usually used for floor slabs in the US, but are commonly used in other areas (don't you use flexible adhesives in your area hokie66?).

As for crack mitigation membranes to use, if it is only for crack mitigation you can use a roll-on product like RedGuard or Mapei. If you want to mitigate both sound and cracking, a sheet membrane like Profiles is used.

 

[ralphi]

Do you guys have experience laying down laminated flooring (what is another term for laminated flooring.. it looks like wood.. but fake wood)?

https://www.youtube.com/watch?v=3jvAV5TanIM

I can't find in any of the videos how to level the floor when installing laminated flooring. Can you put a thin bedding below laminated flooring? How? Thank you.

 

[hokie66]

Some is made of wood,some of bamboo, some other laminates. Available in various thicknesses, qualities, and method of interlocking. I have laid a bit myself, and it is not too difficult after you get the hang of it. Just follow the manufacturer's directions. As to leveling, I don't know. Why is your floor that much out of level?

 

[ralphi]

no problem with floor level as no floor is perfect and one can add little topping...

but i'd like to know guys.. if client gave you to choose whether it's marble/terrazo or laminated floor or vinyl floor.. why would you choose

1. Marble/Terrazzo
2. Laminatd Floor
3. Vinyl Floor

Any specific purpose of each and advantages?

If the place would have gym equipments like barbells & weights.. which covering would be better (this of course assumes the slabs is designed for those loads.. I'm just asking the covering (marble tile, laminated for vinyl floor) aspect).. thank you.

 

[hokie66]

You have them ranked in cost, most expensive to cheapest. Marble/Terrazzo normally for high end use, shopping centres and the like, and in expensive residential. Laminated in smaller commercial premises and in domestic use. Vinyl, cheap. Barbells, maybe a flexible sheet, rubber?

 

[rdubs]

If you are working with a gym that employs barbell weights, then none of the materials you are considering will be durable. Cover the bare concrete with rubber matting or the owner can build wooden platforms where the lifting will take place. Due to the impact loading, I would not try to level the floor - those materials are mostly brittle.