Many consumers and some tile installers mistakenly believe that dimensional (natural) stone tiles are basically the same as ceramic and porcelain tiles. However, there are distinct differences which must be considered.
According to the Tile Council of North America (TCNA) Handbook, ceramic and porcelain tile installations require that the maximum deflection (the up and down movement) of framed floor systems shall not exceed L/360, where “L” is the clear span length of the supporting joist per the applicable building code. For natural stone tile installations, the maximum allowable deflection shall not exceed L/720. This means the floor structure for stone tile installations must be twice as rigid as those for ceramic and porcelain tiles.
For ceramic and porcelain tiles, the average mortar contact on the back of the tile in dry areas is 80% and 95% in wet areas. Conversely, natural stone tiles require that the setting bed in both dry and wet areas be a minimum of 95% with no voids exceeding two square inches and no voids within two inches of tile corners. Unfortunately, the required mortar coverage did not occur in the photo shown here.
Additionally, when selecting installation materials, staining of the natural stone tile can be a possibility. The Handbook states, “Light-colored marbles and nearly all onyx and limestone must be installed with white mortars due to their susceptibility to staining from grey Portland cement mortars.”
Although silicone itself does not stain natural stone, the plasticizers in some silicone sealants can wick into the stone and stain it.
The use of dyes in grouts, epoxies, polyesters, and any other joint fillers should always be tested to verify that the dyes will not leach into the stone, causing a “picture frame” stain. This is most common when the grout color is a contrasting color to the stone.
The sand in sanded grout is generally harder than any of the calcium-carbonate-based stones, such as limestone, travertine, marbles, and some onyx. Protecting the stone surface with masking tape or the use of unsanded grout should be considered to avoid scratching the surface finish especially if it is a high-gloss finish.
