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ZBIZ Review - The Basics

For ZBIZ 2020 we hosted a live virtual event with a panel of certified tile installers to discuss the technical details of installing marble in shower floors. Our conversation centered around the research done over the past two years by installer Pavlo Starykov of Star Tile & Stone. He showed us six modules of shower floors, each utilizing different installation methods and materials, and walked us through the results of each one. Adding to the conversation, we also heard great insight from Dirk Sullivan of Hawthorne Tile, Chris Campbell of Campbell’s Tile Concepts, and Jason McDaniel of StoneMan Construction.

While we dove deep into the various methodologies of installing marble and talked at length about our two preferred methods, we wanted to condense and simplify the most important points for anyone who specifies marble. We have a PDF document with this info as well as a more detailed technical recap available below and the whole discussion will remain posted on our Youtube channel.

Q: What is the potential problem when installing marble in a shower floor application?

A: Marble moisture discoloration.

- This discoloration is not a stain, but a darkening of the stone due to moisture trapped underneath it. Eventually the moisture will evaporate but it can take up to six months to do so.

- Most commonly, the discoloration appears around the drain, around and up the walls, or sometimes around the perimeter.

- The discoloration may be just an unfortunate aesthetic effect but it could also be indicative of much bigger problems under the surface.

Q: So, is marble a suitable material for wet areas?

A: Yes. Let’s get the facts straight.

- Key properties of marble such as density, compressive strength, and hardness are equal to or more durable than many granites.

- Marble has been used in architectural installations for thousands of years.

- Based on our professional experience, most problems that arise with marble in shower applications are due to inappropriate installation methods/techniques.

Q: How do I prevent this from happening to me?

A: Hire a certified tile installer. While some materials like porcelain can be installed successfully by a competent handyman or DIYer, marble should always be installed by a certified installer.

Q: What about sealers? Don’t they keep water out?

A: No. All high quality sealers are breathable, that is, they allow vapor permeability. Water vapor can enter the stone and once there it condenses into a liquid; the liquid then becomes trapped because only vapor can pass through the stone. Eventually, it will dry out but it can take a very long time for the liquid to evaporate and for the resulting discoloration to go away.

Q: What other topics from the discussion should I be aware of?

A: Drains are a key part of the installation. While it’s not important to know all the details about how drains work, it is important to know that there are many different kinds and they vary in quality and functionality. The drain is a crucial component of the shower system and an incorrectly specified or installed drain is often the culprit of a failed installation.

Q: What are the best methods to install marble on shower floors?

A: Depending on factors unique to each tile installation, we have found two methods that provide predictable, long-lasting results with marble.

Method 1: Traditional dry pack mortar bed. Basic unmodified thinset. Unmodified grout. No sealer.

Method 2: Bonded membrane. Bonding flange drain. Epoxy adhesive. Epoxy grout. Penetrating sealer.

Q: How do I clean and maintain my floor? Does it need to be sanitized?

A: For best results, we suggest that you remove excess water with a squeegee, clean regularly with a PH-neutral cleaner, and test your stone annually to see if you should reseal it. An easy way to test it is to put a

few drops of water on the stone and if the water is quickly absorbed, it’s

time to reseal. Marble is a naturally sanitary surface, just use soap and water!

Still have questions?

Call us at 503.419.9786 or email

Keep current on the latest product knowledge and trends by following our social channels:

Instagram @zcollection.usa

Facebook @zcollectionpdx

Download the PDF here:

2020 ZBIZ Recap - simplified
Download PDF • 857KB

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