What is the proper technique for setting tile 12x12 and larger?
Preparation work is the most critical. The floors must be scrapped, cleaned and mopped with all carpets, vinyl or wood removed. The floor should be flat troweled first to insure a complete bond. This is indicated in the instructions for installation on the mortar bag. (We use a bonding agent in this first step to reduce the need for service work in the future.) Metal trim strips should be removed from carpets because the grout will not set up properly against the metal. They should be re-tacked with with “Z” bar to insure they do not ravel with the use of a good vacuum. Commodes should be removed and re-set with new wax rings and water lines to accommodate a new commode if the need should arise in the future.
The era of the 8x8 tile is almost over. Driven strongly by imports and faux marble, 12x12 and larger dominates floor tile size today. The average individual floor tile has increased in size by 80 square inches or 125%. How do you effectively set and beat in such large tiles? Setting materials, tools and technique must all change to correspond with the dramatic change in the tile size.
First, the most commonly used material for setting tile today is thin-set mortar. Medium- bed mortars or non-sag mortar is better suited for the largest tile installations (16x16&over), however thin set still continues as the material of choice. (We use white because it looks cleaner and neater.)
Second, something more easily changed is the trowel size. The larger the tile, the larger the trowel makes sense to most people. A 1/2” round or “U” notch trowel is becoming common. (We use a 5/8” notch for all applications 8x8 and above.) The National Tile Contractors Association Director, Joe Tarver, has concluded that a rounded ridge of mortar compresses and spreads across the back of a large tile more effectively than the traditional square ridge of mortar with a square ridge notch.
Third, the change in technique is critical! In order to maximize coverage of large tiles, the mortar should be combed in one direction rather than swirling the mortar in a random fashion. After combing the mortar in one direction, tiles can be set into the mortar perpendicular to the mortar ridges. Use a “push-pull” motion that forces the mortar ridges to grow together and maximize the coverage. When mortar ridges are combed in one direction, it allows the uniform escape of pockets of air that can be trapped between large tiles and mortar ridges combed in a random fashion.
(Portions pertaining to technique)
Tim Bolby, Territory Manager, Central District
TEC Incorporated 315 S. Hicks Rd. Palastine, IL 60067