What are the issues associated with narrow grout joints? How can rectified tile help?
Commonly
and mistakenly, people assume that using a rectified tile allows them to have a
narrow grout joint. However, there are five separate and important issues that
must be addressed to accomplish a successful narrow grout joint installation:
- Narrow
grout joints provide less room to allow for variation in the size of the tiles.
- Narrow
grout joints provide less room to allow for variation in the layout due to an
uneven substrate.
- With
narrow grout joints, lippage due to an uneven substrate is more apparent.
- With
narrow grout joints, lippage due to varying mortar thickness or limited
installer proficiency is more apparent.
- With
narrow grout joints, lippage due to inherent tile warpage is more apparent.
The
use of rectified tile addresses only the first of these five points. To address
points two and three, it is critical to have a flat substrate. If the substrate
is not flat, then slight variations in floor topography can result in a layout
that requires varying grout joints. Uneven substrates can also contribute to an
increased amount of lippage. While section 4.3.7 of ANSI A108.02, the American
National Standard Specifications for the Installation of Ceramic Tile, allows
for a certain amount of lippage, for grout joints of 1/8” or less the allowable
lippage is only 1/32”, and in general, lippage is far more noticeable with
narrow grout joints. Consequently, an appropriately flattened substrate is
critical for any successful narrow grout joint installation.
Similarly, narrow grout joints can more clearly reveal lippage
due to uneven mortar thickness. To address this (point four), installers need
more time, and compensation for such, to achieve a flat installation when the
tiles are placed close together. For example, dimension stone is commonly
installed with narrow grout joints, and such installations require a much
larger amount of time and material than one would commonly use with a thin-set
tile installation with regular grout joints.
To address point five, certain tile patterns should not be
considered in an installation with narrow grout joints. Whenever the center of
one tile is beside the end of another (for example, running bond or staggered
“brick” patterns) even minimal warpage can create lippage. With regular-sized
grout joints this lippage is not as evident, but with narrow grout joints these
types of patterns are highly problematic.
In summary, narrow grout joints can be achieved with rectified
tile, but only when used in conjunction with proper substrate preparation, when
installed by a proficient installer who is properly compensated for the extra
time required, and when installed in a pattern that will not exhibit lippage
from inherent tile warpage.