How to install porcelain tile
A growing trend with porcelain tile is larger tiles and smaller grout joints, both of which require a very flat floor. For this reason, you may have to use a self-leveling compound.
Porcelain tile has become extremely popular with consumers and is perceived as an upgrade over ceramic tile by many – in much the same way stainless steel appliances are considered an upgrade over white.
Homeowners love porcelain’s ability to closely mimic virtually any type of natural stone, and digital printing technology creates porcelain tiles that look like wood, fabric or just about anything else someone might request.
While it’s true that porcelain tile is basically a refined cousin of ceramic tile, made with basically the same materials and fired in an oven, when you start a floor tile debate there are important differences that result in enhanced performance.
Porcelain is made of finer, denser clay with added minerals ground into a fine dust, and then fired at very high temperatures, well above that of ceramic tile. This results in a denser tile that is harder than most natural stone and has an absorption capacity of no more than 0.5 percent.
Durable beauty, inside and out
Cementitious backerboard makes an excellent substrate for porcelain tile. Make sure to follow manufacturer recommendations for fastener type and spacing for the substrate you’re using.
Porcelain is the tile of choice for moisture-prone areas because of its low absorption rate, and it can be used both inside and out. This makes it a perfect choice for floors that transition to an outdoor space, such as from a family room onto a patio and even to a pool or spa.
The low absorption rate also means the tile’s surface absorbs very little moisture, so spills that might otherwise leave a stain are easily wiped up with a damp cloth. Water and a mild soap are all that’s required for regular cleaning.
Originally, most porcelain tiles were unglazed because they didn’t need that protective top layer, but today most are glazed. Tiles that utilize digital printing technology to mimic the look and patterns of another material are almost always glazed, as the pattern is basically a sprayed-on glaze. This process also allows trim shapes like cove base and chair rails to be made in the same way as the field tiles, resulting in a perfect match.
However, some porcelain tiles are not glazed – and it’s important to know the difference. Unglazed porcelain tiles (also called “polished porcelain”) often have tiny exposed pores that can hold small grout particles that are nearly impossible to clean. If you’re installing unglazed porcelain, a sealer is recommended before grouting.
How to install porcelain tile for best results
For tiles with a lot of ridges or voids on the back, you may have to back butter every tile.
When it comes to install porcelain tile, careful, deliberate installation is critical. The substrate you’ll use to install porcelain tile depends on a lot of factors: floor joist framing size and spacing, how large the tiles are, how small the grout joints will be, expansion joints and cracks in a concrete slab, and the list goes on.
Basically, there are a few acceptable substrates for porcelain floor tile. Cementitious backerboard is usually preferred, and some manufacturers are designing products exclusively for porcelain tile. Exterior-grade tongue-and-groove plywood at least 5/8-inches thick is acceptable, as is one layer of full-contact vinyl sheet flooring.
Concrete slabs make a good substrate, but proper membranes must be installed over expansion joints and cracks. Avoid using interior-grade plywood, OSB, multi-layer sheet flooring, overly glossy or cushioned sheet flooring (even one layer) or vinyl floor tiles. Consult with your tile and/or adhesive supplier for recommended substrates before installation.
Porcelain tile is not only tougher than ceramic tile, it also requires a thinset with a special bonding agent for a tougher bond.
A growing trend when it comes to install porcelain tile is larger tiles and smaller grout joints, both of which require a very flat floor. For this reason, you may have to use a self-leveling compound.
Most self-leveling compounds make an outstanding substrate, but it’s wise to use a product from the same manufacturer as the rest of your setting materials to avoid compatibility issues. Tight grout joints may also require rectified tile, which is ground after firing to ensure uniform size to within thousandths of an inch.
Use a premium thinset with strong bonding agents that are modified with latex – either premixed or as an additive during mixing. This is so the thinset can do some of the flexing for the tile, since the denser, often thicker porcelain tiles can’t flex or move.
Make sure you get at least 80 percent thinset coverage, but know that as close to 100 percent coverage as possible will yield the best results. Back-butter the tiles to get fuller thinset coverage, if needed, and especially if the back of the tile has large cavities or if you’re using large tiles.
Traditional carbon nippers may not be rugged enough for porcelain. Look for nippers specially designed with heat-treated carbon blades that can be re-sharpened and a reinforced center spring for more leverage and durability.
When it comes to the best tools for tile installation, forget traditional carbide cutting tools when cutting porcelain – you’ll want drill bits, hole saws and saw blades with diamond edges. Clean, fresh water helps diamond blades and bits cut cooler, faster and longer, and porcelain tile likes low, even pressure when it’s being cut. As wet saws go, bigger is usually better to install porcelain tile. Look for a 1½-hp motor and the capacity to cut up to 18 inches on the diagonal to handle the large format tiles.
–By Rob Fanjoy
