FLOOR ED
Do Your Tile Installers Trowel Mortar Correctly ?
The way your installers trowel mortar for setting tile makes a big difference . Porcelain tiles , in particular , can withstand extra heavy service conditions by taking a lot of impact or point load when installed correctly over a sound substrate . Improperly troweled mortar creates unsupported space under the tiles , which become weak spots that can be easily damaged by impact or heavy loads
Here ’ s how to avoid these issues and create a strong tile assembly : 1 . Select the right trowel type and notch size 2 . Spread the mortar completely to the layout line 3 . Trowel the mortar correctly in a straight line
Scott Carothers Director of Certification and Training , CTEF Scott is responsible for the creation of the Certified Tile Installer ( CTI ) program , involved in the creation of the Advanced Certifications for Tile Installers ( ACT ) program and provides training to others in the tile industry . He has been immersed in the ceramic tile industry for over 36 years and was the owner of a successful retail and installation firm prior to coming to CTEF . Scott has served as President of the NTCA , Chairman of the NTCA Technical Committee , been named the NTCA Tile Person of the Year in 2005 , and the Ring of Honor recipient in 2013 . He is a voting member of the ANSI and the TCNA Handbook committees .
Troweling mortar in one direction ( left to right or north to south ) yields the best mortar coverage on the back of the tile .
Place the tile into the mortar , moving it in a back and forth motion perpendicular to the trowel ridges to collapse the trowel ridges into the valleys , leaving very few voids in the mortar which supports the entire back of the tile .
Never use these failure-prone tricks :
• Spot bonding with mortar ( dollops of mortar in the corners ) may be easier for setting tiles flat to each other during installation , but just the slightest force will cause a failure . Without proper mortar coverage , air gets trapped with nowhere to go leaving the tile unsupported .
• Swirling the mortar causes voids where the tile is not bonded to the substrate . These voids can result in cracked tile and bond failure under normal use , but especially under point load or impact .
For large format tile , glass tile , natural stone or any tile set on exterior surfaces , “ back buttering ” the tile is recommended :
• Use the flat side of the trowel to get an even coat of mortar , filling all the spaces in the surface of the tile .
• After keying in and spreading the mortar , set the tile firmly , moving it back and forth across the trowel ridges at least the same distance as the width of the trowel notch . Do not twist or move the tile in the opposite direction .
• Straight trowel ridges collapse with the back and forth motion to eliminate voids , achieving a much stronger bond with complete mortar coverage .
• The larger the trowel notch , the more back and forth movement is needed .
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