Aquatic Technology Pool & Spa, "Creating Water as Art."™

Aquatic Technology Pool & Spa, "Creating Water as Art."™
Pools as an art form - the way it should be!

Tuesday, November 18, 2014

Stone Tiles Discoloration - Swimming Pool Expert Witness

It has been well documented that improper installation practices and setting materials can contribute to discoloration of natural stone and stone tile pool decks and patios.

Research Setting Materials

The installer or specifier should always check with the vendor as to the recommended setting materials and mortar and grout colors.  

If the vendor cannot or refuses to provide specifications, then the specifier should turn to the Marble Institute of America (MIA) or the Ceramic Tile Institute of America (CTIOA).

Both of these organizations have published field reports and technical papers regarding the proper setting materials and colors for various types of stone and tiles.

Correct Setting Materials

Some dark setting materials may bleed through lighter porous stones or tiles, creating a clouding, mottling or darkening effect.  Dark grouts can absorb into the sides of the tiles, causing a darkening of the edges.

Conversely, light setting materials can also bleed through darker materials, causing a lightening or ghosting effect.  Lighter grouts can also bleed into the materials, causing a halo effect around the tile edges.

Some epoxy adhesives have been known to cause stones and tiles to curl or twist.

So, it is important to research the proper setting materials for your type of stone or tile.

Improper Installation Practices

Using the incorrect technique when setting some tiles can also contribute to discoloration.  If the setting trowel's gauge marks (aka "comb marks") are not knocked down, then water may accumulate in the resulting voids.  Water saturating the stone, sill cause discoloration and an irregular clouding.

The best method, is to back butter the tiles after a thorough cleaning.  The comb marks are knocked down and the tiles set into the fresh thinset or mortar.  This will ensure an almost 100% contact and few, if any, voids.

Protect the Stone

It is also a good idea to protect the surface of the stones or tiles with a quality sealer or grout release prior to setting the tiles.  This will prevent the edges of the tiles from becoming discolored if grout or mortar gets onto the surface during installation.

A little knowledge will prevent having to tear out large areas of stone or tile.
Paolo Benedetti - Aquatic Artist "Creating water as art."™ 
Aquatic Technology Pool and Spa © 
You may contact Paolo Benedetti at: or at 408-776-8220

Saturday, October 25, 2014

Outdoor floor tiles - proper thinset installation and coverage ANSI A108.5

Efflorescence leaching up through floor tiles, hollow clacking sounds and cracking tiles are usually a result of improper installation practices.

ANSI A108.5 (2005) 
Ceramic tile installation practices are published by the American National Standards Institute (ANSI).  This standards also includes quarry pavers (natural stone tiles). 

ANSI A108.5 - 3.3.2 says that on exterior floors, the average uniform contact area with the thinset mortar shall not be less than 95%.  3 tiles will be inspected to determine the average coverage and compliance.

Both the Tile Council of North America (TCNA) and the National Tile Contractors Association (NTCA) have adopted these standards as the minimum acceptable level of performance and workmanship.

Let's face it, humans beings are like electricity and water - they will take the path of least resistance and effort - lazy !

Trowel marks are actually called "gauge marks."  They are used to create a measured thickness of thinset mortar.  Leaving the trowel marks in place will mean only 50% contact at 100% thickness of the gauge marks.
Improperly installed floor tiles show only 50% coverage.  Buttering the edges will hide these marks and give the "appearance" of 100% coverage.  Click on the image to enlarge.

 A 1/2 inch comb trowel will leave 3/8 inch thick layer of thinset, once the grooves are flattened and leveled.  This means that to achieve a total of 1/2 inch of thinset, both the substrate and tile will require 1/2  inch trowel marks that are knocked down and smoothed.

Why do they do this?  

It saves them 50% on their thinset costs.  
They are lazy.  
They don't care.
No one ever taught them how to do it correctly.  They have never been involved in a construction defect case. 
Tile setters must be reminded that tiles installed in exterior floor and shower applications, must achieve 95% contact with the setting material.

This will ensure decades of performance and a lasting tile floor.
Paolo Benedetti - Aquatic Artist "Creating water as art."™ 
Aquatic Technology Pool and Spa © 
You may contact Paolo Benedetti at: or at 408-776-8220