Ceramic and porcelain tiles are paradoxically both incredibly durable and slightly delicate. These materials are exceptionally tough and long-lasting, and when properly constructed, they create extremely rigid and robust floors that can last for many decades. But for them to function properly, a strong, rigid flooring structure must be underneath. The ceramic tile floor will flex underfoot if the underlayment, which typically comprises floor joists, a subfloor, and an underlayment, is damaged, which will result in cracked grout joints and a ruined installation. Due to this, despite the material's inherent strength, ceramic and porcelain tile flooring might be seen as fairly sensitive. Ceramic tile can perform well with some subfloor/underlayment systems but can drastically fail with other subfloor materials due to concerns with moisture, movement, and adherence.
Underlayment versus Subfloor Understanding the finest installation techniques for ceramic tile requires being able to distinguish between the many parts of a flooring system. Any flooring system, with the exception of slab floors, is made up of three main parts:
- The joists or structural support component.
- The subfloor is typically a layer of plywood or OSB.
- The underlayment is a final layer that sits just beneath the surface flooring and is chosen to meet the requirements of the flooring material.
All three elements are not present on every floor. Ceramic tile is frequently placed directly over a concrete slab in basements or houses with a concrete slab foundation. The effectiveness of any flooring installation, but ceramic tile installations, in particular, depends greatly on the caliber of the underlying support structure. There are six extensively used subfloor/underlayment structures for ceramic tile floors. Tip: Applying a mortar bed or utilizing a cement-based backer board are the best techniques for correctly installing ceramic tile. Board with a cement-based core Cement-based backer board is known by many names but is now widely considered the ideal underlayment for ceramic tile in any application, including floors, walls, and worktops. It can be referred to by one of the popular brand names, such as DensShield, Hardiebacker, or WonderBoard, or it can be referred to generically as cement-board or backer board. Any name you give it, a cement-based backer board is exactly what it sounds like: a layer of cementitious material covered with fiberglass mesh to keep it together.
It is frequently offered for sale in sheets that measure three by five or four by eight feet and are either 1/4- or 1/2 inch thick. The smaller sheets are a little bit simpler to install because this is a substantial material, especially for do-it-yourselfers. The ceramic tile industry was largely transformed when the cement-based backer board and thin-set mortar adhesives were created because they made it easy for nearly anyone to install a structurally sound substrate for ceramic tile. In the past, a qualified professional often laid wet-mortar base layers before ceramic tile floors were put. Cement-based backer boards and thin-set adhesives, which were introduced in the 1970s, not only sped up and reduced the cost of professional installation but also enabled regular DIYers to complete high-quality ceramic tile installations. Plywood of the Exterior Grade Because the bonding adhesives employed are waterproof, exterior plywood is preferred to interior-grade plywood as a tile underlayment. The underlayment won't swell if water penetrates through the tile installation to reach it, unlike interior-grade plywood. The plywood sheets are placed on top of the OSB (or plywood subfloor) when used as an underlayment to create a two-layer basis. Seams between layers mustn't overlap, and it is generally advised against screwing the top underlayment all the way into the floor joists since some lateral movement must be accommodated.
It is significant to note that experts no longer prefer to install ceramic tile atop backer board made of cement; instead, practically all of them do so. However, it is feasible to lay tile atop plywood, and this approach was widely used until cement board was created. Cement Slab: Another effective underlayment for ceramic tiles is a concrete slab. Given that it closely matches the solid mortar bases that were historically typical for ceramic tile installations, it is actually one of the better underlayments. However, the underlying slab must be flat, level, stable, and not prone to settling or heaving. Additionally, being cautious to avoid tiling over expansion joints in the subfloor slab will prevent the tile installation from cracking. An uncoupling membrane can be utilized as an intermediary material to lessen the likelihood of cracking. An uncoupling membrane separates the tile from the concrete flooring beneath it and stops slab cracks from spreading upward to the tile installation. This product, also known as anti-fracture membrane, crack isolation membrane, or crack suppression membrane, is offered under the trade names Schluter Ditra or Redgard Uncoupling Mat. Mastic Bed: A thin layer of cement mortar is poured during mortar bed installations, and the ceramic tile is then directly inserted into it. Typically, a wire mesh reinforcement is incorporated into the mortar layer. The ability to handle minor defects and subfloor irregularities is one benefit of this technology.
The majority of do-it-yourselfers lack the necessary knowledge and time to install a mortar bed. Given that professional installation is a labor-intensive process and that skilled installers are in short supply and in great demand, it may be rather expensive. The weight of a mortar bed is very significant on the floor. Since mortar bed installation is now rather uncommon, you might never come across one unless you're tearing out a floor that was laid with this technique. To lay ceramic tile bases in showers, mortar beds are still frequently utilized. Replacing old ceramic tile with new? It is quite tempting to think of placing the new tile directly over the old because tearing out an old ceramic tile installation is a challenging, untidy, and physically taxing job. The Tile Council of North America (TCNA) claims that this is routinely carried out and is completely permissible as long as certain requirements are followed. For the thin-set glue used to install the new layer to bond firmly, the underlying tile must be in good condition and firmly bonded, and the surfaces of the tile must be scratched and scarified. Additionally, bear in mind the following two crucial points: Two layers of ceramic tile can weigh more than the joists, and the flooring beneath can support them because they are quite heavy. The many hundreds of extra pounds added when a second layer is installed may be too much for a flooring system that was adequate for a single layer of ceramic tile.
The flooring layer is significantly thicker thanks to an additional layer of ceramic tile. This could be a problem if it results in a visible offset to adjacent floor surfaces, like between a kitchen with ceramic tile and a dining room with a wood floor. To account for the height modifications, doors may also need to be adjusted and trim moldings reinstalled. Sheet vinyl flooring with one layer If certain requirements are met, ceramic tile can also be put down directly on top of existing sheet vinyl flooring. For using vinyl flooring as an underlayment for ceramic tile, the TCNA stipulates the following requirements: Wax and other bond breakers must not be present on the sheet vinyl. To create a surface that tile adhesives can adhere to, the extremely shiny vinyl must be scratched or scarified. Only one layer of sheet vinyl is allowed, and it must be securely fastened. It shouldn't have a foam or cushion back, and it shouldn't be perimeter-glued. In other words, confirm that your sheet vinyl is fully adhered to a surface and does not have a soft foam backing. The vinyl subfloor must not deflect more than the L360 deflection threshold, which is the industry standard. Measuring defection is not a simple process for a homeowner. However, if the floor has any "give" to it as you walk on it, it is probably too fluid to support the installation of ceramic tiles. In this situation, the joists need to be strengthened in some way, and/or new, durable underlayment is needed.
Use a utility knife to make a small cut in the center of the vinyl floor to see if full contact adhesive was used during installation. To attempt to lift the vinyl, use a sharp screwdriver or the blade tip. Full contact vinyl is present if it does not lift up. Use a specialized thin-set glue that is designed to bind to vinyl when putting tile over sheet vinyl. When used as an underlayment for ceramic tile, vinyl flooring that is overly shiny or cushioned performs poorly. Whether ceramic tile can be installed over vinyl composite tiles is a matter of debate. According to one school of thought, ceramic tile can be set over vinyl tile under the same circumstances as for full-bond sheet vinyl if the vinyl tile is full-bond installed (rather than peel-and-stick) and in good condition. However, some industry experts believe that a vinyl tile installation is a bad alternative for underlayment due to the numerous seams. Applying a layer of 1/4-inch-thick cement backer board over the vinyl as an additional underlayment is a typical solution for existing vinyl flooring of either variety. If the increased thickness does not pose a problem, this might be an excellent solution. Industry Conflict These six underlayment choices for ceramic tile are endorsed by numerous industry sources, including the TCNA, but not all contractors or industry associations concur. Trade associations that cater to professional installers may contend that the only procedure that may fully ensure a problem-free ceramic tile project is to remove the old underlayment and install a new cement-based backer board.
These trade associations are committed to ensuring that experts receive few callbacks for installation failure. Therefore such comments have some validity. If you employ a tile professional, you might discover that they have different methods they prefer over, say, installing ceramic tile over sheet vinyl. If so, it would be wise to follow their advice. Any contractor's objective is to prevent callbacks due to failure. Therefore, if they suggest a particular approach, it's probably for a valid cause. Poor or inappropriate materials For underlayments under ceramic tile, the following materials ought to be avoided:Interior-grade plywood should not be used as an underlayment because it will swell when exposed to moisture. Similar to interior plywood, OSB sheets don't work well with water.Several vinyl layers: The vinyl floor is fine with one layer. It is not more than one layer. Vinyl with a perimeter bond: Sheet vinyl used as an underlayment for ceramic tile needs to be completely bonded throughout.Hardboard: Avoid using hardboard sheets, such as Masonite, as an underlayment for ceramic tile since they cannot withstand any moisture. Ceramic tile may occasionally be laid directly up against drywall or green board in wall applications. It should never be utilized as a floor underlayment.