Measurement Guide

TB89
GROUT COVERAGE RATES: UNDERSTANDING VARIATIONS
Technical Bulletin
Technical Services 800-282-8786
custombuildingproducts.com
Many different factors can affect grout coverage and
cause variation from expected usage based on
published coverage charts. These range from
variances in tile thickness and surface texture to the
installer’s expertise. Air and surface temperatures can
dry out grout and lower grout coverage. Consider the
following issues when calculating actual grout usage.
Don’t allow grout under the tile
Adhesive and mortar installation techniques can affect
grout because grout coverage calculations are based
on depths, widths and lengths that are symmetrical. To
achieve a consistent joint space, trowel ridges in the
mortar should be completely collapsed under and
between the tiles by using correct setting techniques.
This involves combing straight ridges in the mortar, then
moving the tile side to side across the ridges to
collapse them. Otherwise, grout will push into any
voids left beneath the tile during application. Grout
joints should be cleared of excessive setting material.
TIP- Fill grout joints at least 2/3 full with grout. Especially
when installing an epoxy or single component grout,
allow the setting material to fill the lower 1/3 space in
the grout joint. This method beds the tile more
effectively and saves costs on grouting.
Grout joint widths can vary from the plan
Even small variations in grout joint width can affect the
amount of grout needed for the project. These include
variations in the tile’s thickness, length or width;
tapered, scalloped or chamfered edges; and tile
alignment during the installation.
For example, if the grout joints are calculated to be
1/8", but vary by just 1/32", grout requirement changes
by 25%! The use of grout spacers can assist with
placement and consistency and help to control grout
usage, but the best way to determine coverage is to
perform a mockup using the specific tile material.
Where the grout meets the tile
Grout float hardness and the float’s ability to deform
according to the surface texture of the tile is a
common factor in waste, grout haze and speed.
Matching the grout float to the tile being grouted is
even more important than choosing it based on the
type of grout being applied. If the float is too hard or
too soft, you will lose the squeegee affect that allows
efficient removal of excess grout from the tile.
The surface profile and texture of the tile, along with
overall tile porosity, will affect the amount of grout that
is needed to be spread over the tile and the potential
for loss. Natural stone, unglazed ceramic and raised
textures, such as fabric-look tile, all present a significant
grouting challenge. Pre-sealing the tile using a product
such as Aqua Mix® Sealer’s Choice® Gold or applying
Aqua Mix® Grout Release prior to grouting will benefit
most applications. A smoother, pre-treated surface
presents less opportunity for leaving excessive grout
residue that can form a haze.
Finally, don’t overlook the effect of site conditions on
grout consumption. High ambient and surface
temperatures, as well as direct sunlight, low humidity or
drying winds, can all result in excess grout drying on the
face of the tile before it can be removed effectively
and coverage will be lost in the cleanup.
There is always a waste factor to be considered,
especially on a large project using epoxy or cement
grouts. Full units of epoxy products must be mixed and
used all at one time so the excess mix will be lost.
Ordering smaller units may be appropriate based on
project scheduling. While Portland cement grouts can
be mixed in smaller batches, there will be some waste.
On the other hand, CUSTOM’s Fusion Pro® Single
Component® Grout is ready to use right from the
bucket, with no mixing required. Excess material
spread on the tiles can be placed back in the
container and reused when grouting resumes. Fusion
Pro’s creamy texture is easier to spread, and clean up,
which means installation time savings as well as
simplifying grout coverage.
Always consult the grout’s Technical Data Sheet or the
Material Calculator on the CUSTOM website to help
plan coverage rates accurately.
The information in this bulletin is presented in good faith, but no
warranty, express or implied, is given nor is freedom from any
patent in as much as any assistance furnished by CUSTOM with
reference to the safe use and disposal of its products provided
without charge. Custom Building Products assumes no obligation or
liability therefore, except to the extent that any such assistance shall
be given in good faith.
TB89 8/16