Problems
with Grout
When do you use caulk instead of
grout?
Technically, anywhere there is a change in substrate
or backing surface such as the joint between walks and
floor and wall joint, caulk should be used in place
of grout since these surfaces move independently of
each other. However, it is important to recognize and
make the end user aware of some important points.
Often, installers use grout in place of caulk for these
reasons:
1) The caulk may not exactly match the grout color
2) Even when the caulk exactly matches the grout color
when installed, it may not match 6 months later (Caulk
will "age" differently from the grout.)
3) Caulk will need to be maintained more often than
grout
4) Mold may grow more easily on caulk (except caulk
treated with mildewcide) than on grout
5) Acrylic caulks break down in horizontal wet applications
- silicone, urethane, or multi-polymer caulks are better
choices but can be harder to apply
However, when grout is used in place of caulk, the
grout can cause structural and aesthetic problems:
1) The grout will crack allowing moisture to penetrate
2) Where the grout is sufficiently strong, movement
in the walls, floor, or countertop can damage the tile
3) Grout cannot hide corner cuts as well as caulk
In summary, caulk is the better choice - but the customer
needs to understand its limitations.
What is the difference
between epoxy grout and mortar and conventional grout
and mortar?
We are often asked about epoxy grout and mortar versus
conventional grout and mortar.
Epoxy grout (meeting ANSI A118.3) is quite different
from cementitious grout and epoxy emulsion grout. Made
from epoxy resins and a filler powder, the grout is
extremely hard, durable, and nearly stain proof. Often
times the bond between tiles is stronger than the tile
itself.
You might wonder why this type of grout is not used
all the time. First, most installers find it harder
to use than cementitious grout. Also, it has a more
plastic appearance which, as with all matters of aesthetics,
some people like and some don't. Also, it is much more
difficult to shape and slope; this can be done easily
with cementitious grout and is often needed to transition
from one tile to another. It may also slump in the joint
hours after the floor is finished because the grout
becomes less viscous initially as it heats up and cures.
Lastly, it generally takes days longer to cure and must
be kept rigorously clean. And it can cost 3 to 8 times
as much as cementitious grout.
There are even epoxy grouts on the market impregnated
with Teflon that are both stain proof (nearly) and wipe
clean incredibly easily.
It is also possible to smooth epoxy grout (with or
without Teflon) before it cures in a way that leaves
the surface with an extra slick plastic finish to which
it is very difficult for dirt to adhere.
These "100% solids" epoxy grouts should not be confused
with epoxy emulsion grouts which are a mixture of cement
and epoxy resins (ANSI A118.8). Epoxy emulsion grouts
are not stain proof and generally will absorb liquids
and stains. They are more similar to polymer fortified
cementitious grout (ANSI A118.7) but may have better
chemical resistance than some polymer fortified grouts.
Epoxy thinsets offer greater bond strength and chemical
resistance than polymer modified cementitious thinset.
This performance comes at a price as epoxy thinset is
much more expensive than regular thinset. Typically,
they are only used to bond to difficult substrates or
where extraordinary chemical resistance is needed.
Why is my grout and
tile cracking?
There are many things that can cause excessive deflection
in your subfloor (and consequent cracking in the tile)
or you may have a perfectly sound subfloor but not have
prepared the floor properly for tile.
Here are a few of the most common questions:
1) Is the subfloor plywood over joists 16" on
center? If not, has the installation system been designed
to work with the actual type of subfloor present?
2) What is the span of the joists? - Are they suitably
sized for the span to achieve the L/360 deflection standard
under the expected live and dead load? Are there any
cracked, rotted, or termite damaged joists?
3) Was the subfloor screwed to the joists - is there
any possibility of movement between the subfloor and
the joists themselves?
4) Does the thinset used match the conditions present
(was a polymer additive used and if so was it appropriate
for the subfloor?)
5) Was the thinset coverage satisfactory? What was the
notch size of the trowel used?
6) Were expansion joints used in the installation to
allow for normal movement
7) Are any dimensionally unstable or questionable materials
also in the tile/subfloor/joist sandwich? How about
cushion vinyl, luaun, water-soluble patching compounds
or mortar materials.
8) Were all layers present installed according to the
applicable ANSI standards?
What causes cracked or
loose grout?
There are several things that can cause cracked grout
and we would be guessing as to the cause. It could be
that a field inspection is needed to determine why your
grout is cracking.
Typically the most common causes are as follows:
1) Excessive deflection in the substrate - this movement
can cause the grout to crack, and if sufficiently severe,
can cause tile to crack.
2) Grout that is insufficiently packed into the joint.
This most often occurs with wall tile. If insufficient
force is used while grouting wall tile, it is easy to
"bridge" the joint where the grout does not
penetrate to the back of the joint. This is especially
true if sanded grout is used in joints narrower than
1/8". The sand grains can easily bridge a narrow
joint - in this case the grout may be only on the surface
and have little strength.
3) Grout made with an excessive amount of water or polymer
additive - the liquid that goes into the grout ultimately
must evaporate (except for that consumed by cement hydration).
This evaporation can cause pinholing in the grout and
a weak grout structure.
4) Grout packed after cement hydration started. All
cement based materials have a pot life - if water is
added to the mix after the grout begins curing in the
bucket, the grout will be sufficiently plastic to pack
but will not cure into a hard homogeneous block - rather
it will be crumbly and weak.
Does your installer have any idea as to the cause?
The least likely cause would be defective grout. Some
other possible things to look for:
a) Spacing of joists.
b) Type and size of floor joists.
c) Span of floor joists.
d) Direction of the plywood sheets and placement of
gaps.
e) Were there gaps between the sheets of plywood?
f) Type of adhesive and coverage of that adhesive.
In some cases even the type of tile can affect this
(high or low water absorption tile bodies can vary the
methods and materials needed).
Therefore you can see this can be difficult to assess
without an on-site inspection. Usually minimum requirements
are 16" o.c. (on center) joists (2X10 or better
depending on span), 3/4-inch subfloor with 1/2"
underlayment (or backerboards made for tile). The plywood
sheets should be run with the long side parallel to
the joists (both layers). The top sheet should be installed
so that the joints don't fall over the lower layer gaps
nor above the joists. The adhesive needs to coverage
at least 80% in the dry areas. The grout should be very
dry and well packed into the joints. The joints should
not be flooded with water when they are being cleaned.
Joints cannot be "grouted over" successfully.
At least 2/3 by depth of the old grout needs to be removed
when replacing or repairing grout.
Generally grout fails because of movement of the substrate
or improper mixing and installation of grout. A ¾"-subfloor
with 3/8"-underlayment may not fail but it is marginal
and could cause problems. Stapling the two layers together
could be problematical. The best method is to screw
and glue the two sheets together. The underlayment should
be plywood designed for that purpose too not just any
plywood will do.
Our subsidiary consulting company, TCA-Team, LLC is
available for site consultations and failure analysis
on a fee basis should you desire an investigation.
Standards for Grout
What is the standard for determining
the size of a grout joint?
We are often asked what is the standard for determining
the size of a grout joint - can it be bigger or smaller
- does it need to be a specific size, etc.
There is a relevant standard on page 33 of the ANSI
A108/A118/A136.1 manual. You will see that it is not
specific - however this is the only part of the standard
addressing joint spacing.
ANSI A108.02, Section 4.3.8 - Nominal centerline of all joints should be
straight and of even width with due allowances for hand-molded
or rustic tiles.
In general there is not a specific standard for the
size of a grout joint. However, there are many relevant
parameters that should be considered.
1) What is the amount of variation from tile to tile?
2) Are the edges of the tile linear or irregular (e.g.
"hand-molded")?
3) How big is the tile?
4) What is the surface of the tile; can it be easily
scratched?
5) Where is the tile being used?
6) Is the surface level?
Ultimately, the project owner should choose the grout
joint they desire, keeping in mind that a tighter grout
joint will show more variation from tile to tile. Many
people feel that a joint smaller than 3 times the average
variation from tile to tile (or two times the maximum
variation) tends to look irregular and poorly installed.
Also, grout accommodates differences in the angle of
the surface. Where the floor or wall is not level, the
grout will slope from one tile to another. When tiling
over a hump, the grout joint opens up and when tiling
across a depression, the top of the grout joint narrows.
For cementitious grout, joints smaller than 1/8"
generally should only be grouted with unsanded grout
and joints of 1/8" and larger should only be grouted
with sanded grout. Joints larger that 3/8" usually
need a more heavily sanded grout to accommodate the
large joint.
Some manufacturers sell a "wide joint" mix
(for joints bigger than 3/8") but you can make
the same thing by adding coarse sand to regular grout.
For the exact amounts to add, you should check with
the manufacturer of the grout you plan to use.
Generally, sanded and unsanded grout should never be
mixed - and absolutely never with marble or any other
surface that can be scratched by the sand in grout (note:
marble is a cut product, manufactured to extremely tight
tolerances and usually designed to be installed with
1/16" spacing).
Tile spacing is measured between tile edges - not from
the top edge of the bevel on the tile. The majority
of tile made today has a beveled edge and grout should
not be installed on the bevel. The bevel is often a
glazed surface which is intended to transition from
one tile to another. On some tiles, the installer must
"hand-tool" the grout to keep grout off the
bevel.
A common mistake is to set the tile too close. Often,
the finished results look sloppy due to variations in
the floor or wall and in the tile. Even small variations
can throw off the pattern of the tile if adjustments
are not made in the grout joint. Although 1/16"
of an inch may seem unimportant (on a 12" tile
for example), it represents a 50% variation in a grout
joint 1/8 inch wide. This would be immediately noticeable
and unattractive.
What is the standard
for variations in grout joints?
We are frequently asked, "What is the standard
for variations in grout joints?" We are also asked
about acceptable variations in plumb and level.
These details are discussed on page 33 of the ANSI
A108 standard specifications for the installation of
ceramic tile. While these are voluntary standards, they
are commonly used for commercial construction.
When evaluating grout joints, it is important to consider
that the grout is used to adjust for differences in
the following:
1) Variations in the size of the tile
2) Changes in the plane of the substrate
3) Changes in the thickness of the tile (often this
applies to hand-molded tile)
4) Variations in the rustic profile of the tile
The standards for the manufacture of tile allow for
variation from tile to tile - while the standard details
this exactly, it is not uncommon for some manufacturers
to ship tile with about 3/32" difference between
the largest and smallest tiles in a box.
Grout must adjust for these differences between tiles
so understandably there can be some variation in the
width of a grout joint.
Generally, it is advisable to use a grout joint at
least 2 times the average difference between the largest
tiles and the smallest tiles. A smaller joint will exacerbate
the differences between tiles as the human eye can readily
see very small differences as a percentage of the total
grout joint. For example, while a difference of a 1/16"
of an inch may seem small on a 12" tile, this is
readily apparent compared to a 1/8" grout joint.
As the plane of the tile changes, the grout joint allows
for this change. Should tile go over a hump in the floor,
the grout joint will open; when tile follows a depression
in the floor, the grout joint will narrow.
Clearly grout joints also accommodate both changes
in the thickness and profile of rustic, hand-molded
tile.
Perhaps due to these variables, there is not a numerical
standard to which the tile grout joint must conform.
ANSI A108.02, Section 4.3.8 of the ANSI A108 standard says, "Nominal
centerline of all joints should be straight and of even
width with due allowances for hand-molded or rustic
tiles."
ANSI A108.02, Section 4.3.10 addresses variations in the plane
of the tilework. This section states, "Finish floor
and wall areas level and plumb with no variations exceeding
¼" in 10 feet from the required plane."
However, it should be noted, elsewhere in the standards
the plane of the subfloor is required to be similarly
flat.
Tile installed by the thinset method is really a surface
finish that will follow the plane of the substrate -
as such; variations in the substrate will be reflected
in the tile layer unless additional leveling is performed.
What is causing my
grout to have variations in color?
Uneven grout color is not normal but there can be a
number of things that can cause blotchy grout. Also
how uneven the color appears can be somewhat subjective.
Certain color grouts are not as easy to control. The
easiest colors to work with are the medium grays and
beiges as opposed to bright colors, whites, blacks,
etc. Since most grout is cement based it tends to turn
gray with time and cleaning. Grout sealers are now recommended
to reduce this effect.
Some of the things that can cause color variation include:
1) Too much water added in mixing the grout.
2) Improper cleaning of the grout and grout haze off
the tile (usually by wiping too soon and with too much
water).
3) Leaving plastic spacers in the joints,
4) Having the thinset adhesive fill part of the joint
and showing through.
5) Improper mixing of the grout by using an improper
amount of water
6) Mixing partial bags (this is a problem if the colorant
is not evenly distributed).
7) Using grout from a bag that was previously opened
(and gained moisture during storage).
8) Adding water after the first mixing (rehydrating).
9) Failure to slake the grout.
10) Improper joint packing.
11) Inadequate cleaning of the sponges.
12) Using unclean water.
13) Defective grout itself (this happens once in a while).
14) Dirty tools or shoes that stain the grout (we have
actually had that happen to us, where workers tracked
in clay on their shoes).
15) Foot or other traffic too soon over the joints-curing
time is on the bag but can be up to 3 days for some
grout.
Sometimes the tile itself can have a microporoisty
(small pores in the tile body, especially with porcelain
tile) condition that sucks the moisture out of the grout
too fast or in an irregular pattern.
In many cases it is hard to tell exactly what went wrong
by looking at the tilework. I would suggest that you
ask the tile installer what he or she thinks about the
workmanship and techniques used. One can always remove
the grout and replace it if that is the only acceptable
solution.
If you have some of the grout left, the TCNA
lab can test the grout.
Our subsidiary consulting company,
TCA-Team, LLC is available for site consultations
and failure analysis on a fee basis should you desire
an investigation.
The color of the grout
in my shower is inconsistent and in some areas the grout
is a darker color?
Uneven grout color is not uncommon - although in this
case, the darkening may be caused by water (more about
that later).
This is in part because some colors are more prone
to uneven color than others due to the dyes used. Also,
depending on the tile, it may be impossible to allow
the grout to sufficiently cure for best color uniformity
and still remove it from the tile. In other words, the
grout must be removed before the color has a chance
to set.
However, there are many installation mistakes that
can cause uneven color including improper mixing of
the grout (typically by using too much water), mixing
partial bags (this is a problem if the colorant was
not evenly distributed), using grout from a bag that
was previously opened (and gained moisture during storage),
adding water after the first mixing (re-hydrating),
failure to slake the grout, improper joint packing,
using too much water too soon when wiping the joints,
inadequate cleaning of the sponges, using unclean water,
allowing traffic on the floor too soon, etc.
You asked how to achieve uniform color - where absolute
color uniformity is desired, epoxy grouts are often
recommended (they are much more expensive though) as
they cure and clean up differently from cementitious
grout.
Is there a standard that
addresses color variations in grout?
There are no ANSI standards that address color variations
in grout.
This is in part because some colors are more prone
to uneven color than others due to the dyes used. Also,
depending on the tile, it may be impossible to allow
the grout to sufficiently cure for best color uniformity
and still remove it from the tile. In other words, the
grout must be removed before the color has a chance
to set.
However, there are many installation mistakes that
can cause uneven color including improper mixing of
the grout (typically by using too much water), mixing
partial bags (this is a problem if the colorant was
not evenly distributed), using grout from a bag that
was previously opened (and gained moisture during storage),
adding water after the first mixing (rehydrating), failure
to slake the grout, improper joint packing, using too
much water too soon when wiping the joints, inadequate
cleaning of the sponges, using unclean water, allowing
traffic on the floor too soon, etc.
Where absolute color uniformity is desired, epoxy grouts
are often recommended (they are much more expensive
though) as they cure and clean up differently from cementitious
grout.
Unfortunately, with regular cementitious grout, there
is little that can be done once the grout is in place
except for attempting to use a grout colorant. Grout
colorants work best with grout that has not been sealed.
Grout that has been sealed, or has been washed with
oil-based soaps (Pine Sol, Murphy's Oil, etc.) can be
very difficult (or impossible) to color.
The edge of the tile also makes a difference in the
success of the colorant - tiles with well-delineated
edges are easier to treat than tiles with a large bevel
or textured edge. When the colorant is applied, some
will get on the tile - the easier it is to remove from
the tile (and the better it sticks to the grout), determines
in part how good the finished result appears.
Grout treated with a colorant also has a different
texture than originally colored grout. On the plus side,
grout colorants usually seal the grout in addition to
changing its color. Typically, grout that has been treated
with a colorant does not need to be sealed.
Repair & Removal of Grout
How do you remove grout that
is adhered to a tile floor?
Removing grout that is adhered to a tile floor can
be difficult. The type of tile greatly affects the difficulty
of grout removal; also, if the grout was polymer modified,
it may be more difficult to remove.
In general, the more porous the surface, the better
grout will adhere - conversely, grout is more easily
removed from dense impervious tiles (e.g. porcelain).
To remove the grout, start with an alkaline cleaner
and a nylon scrub pad. Make sure to check that the scrub
pad is not damaging the tile. Normal floor tile will
not be affected by a using a scrub pad, but some decorative
tiles do not have the same surface hardness. It is best
to check your decorative in a secluded area.
If the scrub pad is not effective, there are specialty
cleaners on the market that chemically attack the grout.
Typically these are weak acids. As with all acids, follow
the manufacturers warnings carefully and use caution.
Always check the tile in an inconspicuous spot first
in case the cleaner affects the tile.
Again, these specialty cleaners will not affect most
floor tiles - however, it is prudent to check.
Some tile installers use stronger acids that they carefully
dilute. While experienced professionals can do this,
there are great risks in doing so. There is the possibility
of bodily harm as well as damage to the surroundings.
Can I paint over grout?
Changing grout color is more commonly done but again
the results are generally not as good as the original
item. The color in grout, unlike tile, comes from liquid
dispersed pigments. Obviously, these are not fired but
rather become part of the cement/sand matrix. Grout
is usually colored with an epoxy paint made for the
purpose and sold in tile shops. When the grout is new,
has not been sealed, and the edge of the grout joint
is neatly defined and when the adjoining tile surface
is very smooth, sometimes good results can be achieved.
However, if the grout is not porous (from sealer or
dirt), or the adjoining tile is rough or absorptive,
it may be impossible to get a satisfactory result.
Can I correct the color
of my grout?
When grout has been stained to the point that it cannot
be maintained or returned to its natural color, you
can return the grout back to near its original color
or any other color through the use of a "grout
stain". Some grout manufacturers make grout colors,
others will recommend specific brands that they know
work with their grout to correct color.
However, grout colorants work best with grout that
has not been sealed. Grout that has been sealed, or
has been washed with oil-based soaps (Pine Sol, Murphy's
Oil, etc.) can be very difficult to color.
Grout Stains are epoxy-based products that are specifically
designed to penetrate into the grout and seal the surface
with a permanent color. Once the grout has been stained
there is no need to seal it any further with a penetrating/impregnating
sealer.
Prior to staining, the grout joint should be cleaned
thoroughly to remove any dirt, oils, grease or sealers
with a professional strength Tile & Grout Cleaner.
This can be purchased from most Home Centers or through
your local Professional Floor Covering Dealer.
The edge of the tile also makes a difference in the
success of the colorant - tiles with well-delineated
edges are easier to treat than tiles with a large bevel
or textured edge. When the colorant is applied, some
will get on the tile - the easier it is to remove from
the tile (and the better it sticks to the grout), determines
in part how good the finished result appears.
Also, you will want to try a test area since grout
treated with a colorant does not look the same as originally
colored grout. On the plus side, grout colorants also
seal the grout and protect it with an "epoxy-like"
finish. Typically, grout that has been treated with
a colorant does not need to be sealed.
Cleaning Grout
How do I clean grout?
Cementitious grout, as you may have observed, is porous
- it can absorb a stain. Looked at under a microscope,
there is a large surface area to absorb stains. For
this reason, many owners choose to seal their grout
… usually the better the sealer, the more the grout
joint is protected. Even better, if epoxy grout is used,
it is virtually as stain proof as the tile.
Removing stains from cementitious grout is similar
to removing stains from clothing. The same cleaners
you might use on clothes to get out a stain should also
work on grout.
Keep in mind though, that grout is based primarily
of cement and sand. Sand, like glass, is unaffected
chemically by most cleaners. Cement is not; rather it
is alkaline based and is dissolved by acids. As baking
soda and vinegar react, so do grout and vinegar.
Accordingly, it is better to clean grout with an alkaline
cleaner (Spic and Span, Mr. Clean, etc.) than an acid
based cleaner. There are also specialty cleaners available
at most tile retailers that are designed for tile and
grout. There are also cleaners with enzymes that attack
stains similar to enzyme pre-soaks for laundry.
The same cleaner that works on the grout generally
will work well on the tile. In fact, since the tile
is usually so easy to clean, the tile can often be cleaned
with water.
Just a few more important points: As the grout can
absorb the soap as well as a stain - do not clean with
oil or wax based cleaners - Murphy's Oil soap, Pine
Sol, etc. These products will leave a waxy or oily film
in the grout… And, even good alkaline cleaners
if not properly rinsed, will leave a sticky soap film.
This usually attracts dirt. In fact, truly clean ceramic
tile without any sticky soap film will stay very clean
as tile does not tend to hold an electrostatic charge
(which can attract some kinds of dirt).
The absolutely best way to clean grout is to apply
the cleaner and then vacuum ("shop vac") up
the dirty water. This lifts the dirt off the joint.
Apply rinse water and vacuum that water up. This lifts
off any remaining soap film.
Just to mention it, there are tile installers that
remove very stubborn stains on grout with an acid (like
straight vinegar or a stronger acid). There they have
elected to dissolve the top layer of grout molecules
so the stain is no longer attached to anything. While
this works, it is not recommended by the grout manufacturers
- needing to regrout is sometimes the result. Also,
extreme care should be used when handling any acids.
Should you be unable to get your grout clean through
conventional methods, you may also want to try steam.
Some stains that do not respond to conventional cleaners
will come clean when subjected to pressurized steam.
As a last resort, some installers elect to cut out the
grout and regrout. This is possible although care must
be taken to not damage or loosen the tile. Generally
it is not possible to grout directly over the old grout
without cutting the old grout out. The same contaminants
that made the old grout dirty may prevent new grout
from sticking properly.
How can I prevent my grout
from staining?
To prevent staining in the future, you should seal
the grout.
Generally, sealer is a very good idea for cementitious
grout (regular grout - not epoxy grout). For glazed
floor tile it is not a good idea to spray anything on
the tile - the glaze of the tile will be easier to clean
and longer lasting than any coating. For unglazed tile,
generally sealers are recommended although it is important
to follow the recommendations of the tile manufacturer.
For cementitious grout, there are two broad classes
of sealer: Penetrating sealer that chemically bonds
with the grout and repels water (and water based stains)
and topical sealers that coat the surface of the grout
and repel almost everything (until they are worn off
by foot traffic).
Each type of sealer has its advantages and disadvantages.
Additionally there are hybrids on the market combining
advantages.
In general the topical sealers are less expensive but
give the grout a plastic appearance. Also they are subject
to wear and tear and very sensitive to water in the
grout while curing. As stated above, the plastic coating
does block almost everything…until it is compromised
by foot traffic.
The penetrating sealers are more expensive but also
more durable. There are also penetrating sealers that
repel oil based stains that are even more expensive.
They can be applied on the grout sooner than the topical
sealers, as they are usually vapor permeable. As they
do not coat the grout (but penetrate in), they do not
change the large microscopic surface area. While stains
don't penetrate, they can be a little harder to remove
(just a little) because the sanded texture of the grout
hasn't been changed.
For more information about sealers, click
here.
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