Tile Setting
Surface Preparation
Welcome to ceramic, porcelain, and stone tile Surface Preparation. This is the start of where the rubber meets the road. This section will describe in general terms what can be found in the areas of The Tile Doctor dealing with the specific ceramic, porcelain, or stone tile installation requirements. If the project is to be a success, a careful examination and preparation is critical. When projects start out right they will end right.
Structural Integrity
According to ANSI 108 AN-2.4 1999, tile can be installed over horizontal and vertical building surfaces that are “sound, clean, and dimensionally stable.”
“Sound” means that the surface is stable and well cured in the case of concrete surfaces. “Clean” means that the intended surface is free from surface contaminants that would affect the bond strength of the tile. “Dimensionally stable” means that the framing and supporting members are sufficiently constructed to support the installation.
How do we ensure that our project meets these recommendations? First, we put these specifications into a contract.
Then we insure that the project meets the specifications through inspection. Inspection means that we closely look at the job to ensure that framing members are the correct size and are spaced and nailed properly. We also ensure that if the framing members are covered with plywood or gypsum board, that it is installed correctly. In the case of cabinetry, that it is installed correctly.
Next we would ensure that the installations are level or plumb and true to plane according to the specifications. We would also ensure that rooms and enclosures are square or at exact right angles with each other. The basic rule is that framing and surfaces need to be level, plumb, and true to plane within 1/4″ in 10 feet. To check for level or plumb, a spirit level works very well.
I use a 6-foot level for floors and walls where space permits and smaller levels when necessary. To check a surface for “true to plane” a level or straight edge can be used. Running it along the intended surface noting any deviation or high or low spots will do the trick. Checking for square can be accomplished by the use of a hand held square. The other way is mathematical in nature and is called the “3-4-5″ method. For more on these methods and their application, go to the Estimating/Layout section.
New Construction
Wow! Wouldn’t it be great if we could start from the ground up? This would mean that we could specify huge joists with close spacing and very strong wall framing and the like? Well, sometimes that is possible. Most of the time, we are subject to budget, time and skill constraints. Nevertheless, in each specific section we will discuss the minimum standards necessary to achieve satisfactory results. Lets look at some basic industry standards for surfaces intended for stone or ceramic tile.
Concrete or Masonry: ANSI recommends concrete or masonry to be “dry, structurally sound, and free of wax, curing compounds, or other coatings.” The surface needs to be flat without deviation exceeding 1/4″ in 10 feet or 1/16″ in 12 inches. In addition, the surface needs to be free of cracks or voids. The surface should have a steel trowel and fine broom-finish.
How do I check for surface contaminants? A simple method is to place water on the concrete surface and watch to see if the concrete readily absorbs it. If it is readily absorbed, the concrete is free of obvious contaminants that might adversely affect the bonding of tile. The absolute best way to ensure that a slab is ready for tile is to sandblast, beadblast, or scarify it.
Concrete Cracks
What about cracks or voids in new or existing concrete slabs? Basically, all cracks and voids need to be repaired prior to the installation of a tiled surface when the tile is being directly bonded to the concrete. Unsuppressed cracks can and will transmit from the slab up through the finished tile surface.
There are two types of cracks. Shrinkage or minor meandering cracks can be repaired with any number of “crack-suppression” products available.
These minor cracks will be narrow and will not have a height difference from one side of the crack to the other. Large wide cracks that do have a height difference are structural cracks requiring a method other than a direct
