Q&A / 

Marble Floor

HI TIM: So glad I found you.We bought a new home 4 years ago in Vegas. I wanted marble. We have 1200 sq. ft. of marble downstairs. We recently noticed tons and tons of cracking on the marble. The marble cracks are all over, different directions, all rooms. Some are very long. A builder is coming out in 2 weeks to check them out. I spoke with the contracting company who layed the marble and was told they used thin set. Could it be the foundation? This job cost us over $25,000. Who should be responsible to take care of this? We see new cracks starting as well. The existing cracks are not small either. Can you give me some advise on this? Also is there a marble cleaner that would help clean my marble flooring and grout? Thanks so much. - Linda, Las Vegas, NV

DEAR LINDA: If I could come to your home, I'll bet I'd discover that the cracks in the marble are directly over cracks in the concrete slab.

In Las Vegas, your builders pour concrete on the dry soil that's really gravel. If they didn't put in reinforcing steel or use fibers in the concrete, the concrete can develop significant cracks that pull apart. Had they used steel or fibers, the cracks would be hairline in nature.

I'm sure your slab has shrinkage cracks. Concrete shrinks as it cures. It can lose 1/16th of an inch in length for every 10 linear feet.

The marble then cracked because it was locked to the slab with the thinset.

The marble setter should have put a crack isolation membrane down on top of the slab. That way the slab could crack and the marble would have floated over the slab. What a shame!

I recommend that you now just grout the cracks with a grout that matches the color of the marble or is actually a color of the veining in the marble. This way the cracks will appear as if they are part of the marble. It may take repeated grouting to ensure the cracks all get filled. Done correctly, a visitor to your home will never know that the marble's cracked.

You can fix the unsightly cracks in the marble by just regrouting. It's not as hard as you think and I have a four-part set of videos that shows you how you might do this yourself. Here are the links, in order, to the four videos:

As far as marble floor cleaners, oxygen bleach does a great job of cleaning marble flooring. Oxygen bleach is a grout cleaner also.

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4 Responses to Marble Floor

  1. Hi, just finished building a 9000 sq ft home and waiting for final inspection next week. I have around 2500 sq ft of ‘bianco gioia’ Marble
    In the main living areas. The foundation was poured around a year and a half ago and Marble was installed 3 months ago. Today when the house was cleaned, we noticed cracks in the marble travelling through 5-6 Pieces of marble. I checked the entire Marble flooring and noticed the same problem in four different areas. Each area has 5-6 damaged pieces. Iam very, very upset. It took us 2 years to complete this house and now just as we are ready to move in, we have this new issue. You seem to have all the solutions for Marble and granite problems. Please help me! Just a few questions.
    1. Are these cracks due to foundation shift.
    2. If so, the foundation was poured a year before the stone was installed.
    3. Could it be that this particular kind of Marble is too soft, and prone to cracking.
    4. Could we change all those pieces now. They are around 24 pieces of 18″x18″ size.
    5. Could it be the installers fault. All I know is that he put only thin set under the marble.
    6. Are these kind of problems common
    7. Usually is it covered under builders or installers warranties.
    8. Could we get more cracks?

    • Mirza, your question requires lots of typing, plus I have some questions for you so I can give you the correct answer(s). I only do pithy answers here in the comment section. If you want to protect the investment you have in your house and not waste time or money *hoping* you make the right decision, you should talk to me on the phone for just 15 minutes. It'll be the best investment you've ever made in your home!

  2. Dear Tim,

    We had installed 20mm marble flooring over a raised flooring panels. Sandwich between the flooring panels and the marble are 9mm cement boards. We recently noticed that cracks ran along the length of the marble and upon removing the cracked marble for replacement, we noticed that the cement boards cracked on the same location as the marble. While the raised flooring were also panels, the joints on these panels do not coincide with the cracks on the marble and or cement board.

    Appreciate your help.

    Manuel - Dubai, UAE

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