Success with ceramic tile as a finishing material always
depends on the materials that support and surround it. Grout is
a key ingredient, because grout determines whether or not the
finished joint will perform as expected.
Ceramic tile grout is both practical and decorative. Cured
grout protects the fragile edges of tile and supports
compressive loading, which is especially important for floor
tiles. Also, when grout is properly installed, the tile can be
easily cleaned and maintained, which contributes to the overall
appearance of the installation. Once cured, Portland
cement-based grout is immune to damage by water (even when
fully immersed, as it would be in a swimming pool or fountain).
But contrary to popular opinion, grout is not a waterproofing
material that can eliminate the passage of water or
Many types of grout are available to suit different kinds of
tile as well as various performance conditions ranging from
dry, light-duty wall tile to wet locations with heavy floor
traffic (see ","). In this article, however, I will be talking
about Portland cement-based and latex grouts. Epoxy grout
differs radically and is best left to another article.
grouting, the tile joints must be cleaned of all adhesive
residue to a depth equal to two-thirds the thickness of the
tile. Ideally, excess adhesive should be removed while it is
still soft. If the adhesive has hardened, use a narrow
tuck-pointing trowel, a utility knife, or a scraper to pare
down any excess (see Figure 1).
1. Patches of excess adhesive buildup in the joints can
cause splotches on the surface of colored grout. If the
adhesive hardens before it can be removed, cut away any excess
with a tuck-pointing trowel or scraper to a depth of two-thirds
the tile thickness.
This is particularly important when applying
colored grouts, since variations in the joint depth can cause
splotchy color at the surface.
Temperature and humidity also affect grout. In hot climates,
if supplemental cooling is not available, it may be necessary
to apply the grout early in the day, before temperatures rise.
At the other end of the thermometer, temperatures below
50°F will suspend hydration. In this case, you may need to
provide supplemental heat till the grout has fully cured.
Beware of unvented heaters. Carbon monoxide and other
contaminants in the exhaust pose a health threat to tile
workers, and may react with and degrade the grout as well.
The types of tile and adhesive used also affect the grouting
process. Non-vitreous tiles and regular adhesive mortars absorb
moisture. For these applications, misting the tiles with a
garden sprayer or washing the tiles with a damp sponge just
before grouting can help improve the strength of the finished
grout and speed up the grouting process. On the other hand,
vitreous tiles and low-absorbing adhesives (like some cured
mastics and latex or epoxy adhesives) do not require misting or
sponging. When conditions call for misting or sponging, keep
water from puddling in the joints. Even small droplets of
excess water in the joints can weaken any grout and cause
variations in the hue of colored grouts.
demands at least one specialized tool — a rubber trowel
that can compress grout into the joint without scratching or
marring the face of the tiles (Figure 2).
2. A rubber trowel is essential for grout
work, because it forces grout into joints without
marring the tile surface.
Margin and pointing trowels are useful for mixing, placing,
or trimming fresh grout.
Clean buckets are essential, as are soft cloths or towels
for removing cement haze from the surface of the tiles.
You’ll also need round-edged sponges, available at tile
and masonry supply houses. A powerful shop vacuum is great for
final cleaning, and don’t forget barricades to keep
traffic off freshly grouted tile.