The Grout Master
March 28, 2008
Who is the Grout Master? Hopefully, it is you or someone in your company. Grout is one of the areas in ceramic tile installation that has remained unchanged for centuries until recently. Grout seems to be the second most hated word in the tile industry right next to surface prep. Manufacturers have been introducing an ever-increasing array of products in this category to change that perception. My personal opinion is they have nearly all been great improvements on the simple sand and cement formulations of days past but like sand and cement, they don’t work if you don’t follow the instructions. Just what was wrong with simple sand and cement anyway? Not much really from my perspective. When you have the time and skills to properly install grout in the tile work, sand and cement are more than up to the challenge. The areas where things get a little more complicated are: when you introduce poorly trained sales personnel; creating unrealistic color expectations; adverse working conditions; excessively deflecting wood structures and untrained installers; in these cases, grout gets considerably more challenging. It is the desire to accommodate these challenges that has caused manufacturers to invest great sums of money in making simple and easy-to-use products. Some no doubt feel that is a very argumentative statement given some of the very specific instructions that must be followed to achieve the advertised performance. One thing you cannot engineer into the manufacturing process is common sense and the need to follow basic instructions. Still, that only addresses grout product issues. In today’s tile market there are also some practical considerations beyond grout products and the installation process.
Let’s start out by looking some of the common sense aspects of grout and grout joints. I mentioned sales personnel early as a problem and in my view, it is an ever-increasing area of concern. Big tile and patterns are the rage these days and the source of an increasing amount of complaints. Most end users desire very small grout joints; indeed, many would prefer no joint at all. Some are quick to point out that many old installations have tight joints and are a hundred or more years old. That is true, but the secret of very small grout joints used in days past is because the installation method, wet set mortar, allowed for such demanding tolerances of flatness in the substrate. In the old mud method, tile is beat into a level plane over a fresh plastic mortar bed. That is a rare luxury in today’s installations due to both structural and skill considerations. Using direct bond methods such as thinset, it is nearly impossible to affix an 18” tile dead flat where small grout joints would be satisfactory. Generally speaking, the industry referred to floor flatness standard of a ¼” in 10’, no more than a 1/16” variation in 12” works with 8x8 tile; you may even get lucky with a 12”x12” tile now and then. But, you should not expect regular success with a larger size tile unless additional floor preparation is done prior to the installation. Then there is the tile size variation to consider. Years ago we had 4x4, 6x6, and some 8x8 tiles. Given their small size, some minor percentage of variation was not a big issue, literally. Size variation is a fact of life in the tile manufacturing process as is warpage. A certain degree of each should be expected in all ceramic tile products, even rectified tile. On large size tile even while the percentage remains small, .075% under the new standards, that can add up as the size increases.
We thoroughly explained tile size variation allowances for both normal calibrated tile and rectified tile in last month’s Floor Covering Installer magazine. If you missed that issue, you may want to get a copy. And, keep in mind, rectified tile will have a specific allowable variation for the first time; there is no current requirement. Along with the new size variation limits there will also be a specific grout joint width recommendation coming in the new industry installation recommendations. That will call for a grout joint width three times the anticipated variation in the tile. Even with the new rectified tile standards that would result in a minimum joint recommendation of just over a 1/16” and roughly 3/16” for normal calibrated tile. From a practical point of view, to be a true Grout Master, you must understand the limits of the substrate and tile product on the grout joints well before the installation commences. If your boss, store, or retailer does not understand these limitations, you must educate them in the interest of remaining profitable while having happy customers.
While smaller grout joints is an increasing concern with the large tile preferred by customers, the largest concern remains the actual grouting process. Ideally, grout has two functions: to protect the edges of each tile by providing support and to provide a contrasting or complementary framework surrounding the tiles. Both are very important and the aesthetics and performance are dependent on the skill of the installer. Unfortunately, many contractors, installers, distributors, retailers and homeowners think that grout is also a miracle material that can absorb any movement, is stain-proof and probably the most common misperception; it will completely eliminate water or moisture penetration. To add to the confusion, the market is bursting at the seams with all kinds of grout products such as ready-to-use, plain, sanded, latex modified, acrylic modified, polymer-added, epoxy emulsion, and 100% solids epoxy. What does it all mean, and which type should you use? I don’t think there is a set answer to what is best; it really varies with application. The old standbys have always been unsanded grout for joints less than 1/8” and sanded grout for joints over 1/8”. While that holds true today, many new products have a wide range of joint size abilities, some from a 1/16” to ½”. There are also some “stainproof” grouts; a few additionally offer that there is no shade variation. These come in both cement and epoxy types. Mixing, application, and clean-up recommendations vary widely based on the formulation of the grout. When using hi-performance grout, strict adherence to instructions must be followed. In our training classes we consistently have demonstrated that old methods and techniques do not necessarily work on modern products. We have much less trouble teaching those new to the trade with no prior experience than seasoned veterans when it comes to new products. Sometimes it is almost comical how the newbie who read and followed the instructions with no preconceived notion outshined the “veteran” installer. We also demonstrate regularly that we can mix, install, and clean epoxy grout in less time than the most experience installer can do with cement products. We have done that demonstration a number of years and while it has been close a few times, the epoxy always wins! Any bettors?
All grouts do share some basic similarities:
- Dye lots: Manufacturers use multiple locations and blend numerous different colors during the normal course of production. Always check the dye lot. On larger jobs you should blend bags dry to achieve the greatest consistency in color.
- Clean buckets and good potable water: The need for clean buckets should be self explanatory. Clean water can be hard to come by on construction sites with new wells. High amounts of chemicals good or bad can cause problems.
- Use of a low-speed mixing drill: Too much air results in weak grout. If you’re using a 3/8 drill, you are mixing too fast. 100 to 300 RPM is the range depending on manufacturer. Yes, recommendations vary.
With sanded cement grouts typically in use, there are a few added considerations that may affect shading:
- Overglazed edges on the tile: This is a common practice done intentionally by some European manufactures where the expose edge is used as trim.
- Glaze on self-spacing lugs in wall tile
- Porosity of the tile body. Impervious tile will prevents the rapid absorption of water versus a wall tile that will rapidly absorb it. There WILL BE a color difference.
Some other basic recommendations include but are not limited to:
- If a light colored grout is to be used, hopefully we installed the tile with white thinset.
- The thinset in the joints should be of uniform thickness. Troweling parallel to the tile and positioning your next piece directly next to the previously installed tile makes this much simpler to achieve.
- The tile should be wiped down with a damp mop or sponge. Moistening the surface prior to installation goes a long way towards easier cleanup. Otherwise the tile surfaces first exposure to moisture will be the moisture in the pigmented grout, not a good idea.
- Tile setters do not own fans. Grout must cure at its own pace. Fans cause rapid loss of water resulting in lighter color and weaker grout joints.
- Caulk all movement joints and inside corners prior to grouting. In wet and exterior applications a sealant should be used.
Proper grouting takes a fair amount of skill and understanding of the product. Assuming the tile has been properly installed, the person doing this job will give the end user great pleasure and easy maintenance or a lifetime of misery and grief. Skill is needed to achieve proper joint filling, depth, and color. The lack of it is apparent to those of us on the technical end by the calls and emails we receive every day, and I mean every day. By far the most common cause of grout complaints is excess use of water. This can be either in the mixing process or clean up. When mixing, proper drill speed and water ratio are very important to the thoroughly mixed product. Excessive speed results in too much air, causing pinholes, color loss, low compressive strength (powdery joints), and very little working time. The slower, the better. Most of the water used in cement products is called “water of convenience;” that means what is required to get it out of the bucket, on the floor, and in the joints in a reasonable manner. For the untrained installer, more water is more convenience. Why push that grout float and get a sore arm when we can almost pour it in the joints? Excessive shrinkage, poor strength (powdery), and mottled colors are good reasons why not. There is no corrective measure for poorly installed grout and grout products short of removal though some may choose to argue by offering products to mask the effects. Sealers will not take the place of doing a good grout job in the first place.
This is a subject that could no doubt fill a small book given all the products available and cleaning variations in use today. This article is not meant to be a definitive look at the rights, wrongs, and how-to’s of a somewhat complicated subject with so many product variables. However, it does cover the largest areas of concern based on the calls we receive. Sales people need to provide more realistic expectations on tile size variation and grout joint width recommendations based on typical substrates. Customers wanting very small joints with large tile should be aware of the premium price for such work. They also should better prepare their customers for the inevitable variation from the samples they use in selecting the grout. Installers need follow instructions set by the manufacturers to minimize grout complaints. It is much easier and faster to install grout correctly than incorrectly. This may sound strange, but it is true; it just takes a little planning.