What causes Stress Fractures or Indent Fractures in Natural Stone?


I'm having an issue with a floor I did overyear ago, it's a carrera Marble. We installed 1/4 " durarock, used 4 or 5 bags of levelquick to flatten the floor, installed Warm Wire, and used Versabond to install the floor.

You can't feel any cracks in the tile and the grout is intact, but you can see some spider like veining going on.

The home owner first started noticing the veining about I months after if was installed. Yesterday I took up a piece to see what was going on and noted that the veining went all the way through the the thin-set and the level quick. the thin-set is 5/16 thick.

My question is how soon after the Marble is installed does the shrinking happen?

Can the warm wire have anything to do with this?


ANSWER - We have seen this condition in marble before.  They are referred to as indent fracturing or stress fracturing veins.

You said that the veins went all the way through the stone, the thin-set, and the level quick.  So was there a crack in the thin-set and level quick in line with the stress veins?   Or what do you mean veins when through those materials?

Normally what we see is that there are shrinkage cracks that start in the self-leveling underlayment or thin-set.  Those shrinkage cracks cause the stone to begin to crack at the bottom, which is what causes the stress veins.

Typically the underlayment or thin-set was too thick and/or too wet that causes excessive shrinkage.  The shrinkage is like a dry lake where you get pads of shrinkage that separate from each other.  The cracks are areas of tension where the pads are pulling away from each other due to the shrinkage.  This then causes the crack and stress that leads to the stress fracturing veins.

Shrinkage is part of the curing process so it starts as the materials cure.  It is possible that the floor warming may have accelerated the shrinkage if it was turned on before the thin-set and self-leveling were fully cured.   So it could be a contributing factor.  There could be other contributing factors such as no or not adequate movement joints.

Once everything is cured then the shrinkage stops, but it can cause tension in the assembly that eventually can cause the stress fractures.

The fix is replace the tiles that have the condition.

Leave a Reply

Your email address will not be published. Required fields are marked *