Filing a Construction Complaint is the last thing anyone involved wants to think about after completion of — or worse yet — during the project. As with all trade work, expectations and performance in workmanship and materials can be challenging and have different meanings for the different stakeholders of each job. During the design phases of a project, even the best efforts often overlook the most appropriate tile grout for the assembly. Unfortunately, when it comes to tile installations, grout callbacks are on the top of the list.
How does an architect or tile contractor select the right type of tile grout for a project? The design team or owner can pick colors to enhance or complement the tile palette, but will just any grout perform long-term under the conditions experienced within the facility? Of course, tile contractors typically want a grout that has ample working time in various conditions, fills joints easily and completely, dries fast and cleans up with the least amount of time and effort.
What does the owner or designer want? Maybe no grout at all, but realistically, grout is absolutely necessary for many reasons — not least of which is a smooth surface. For instance, not all tile is absolutely uniform in size from one piece to another, so there are allowable variations found in the American National Standards Institute’s (ANSI) Specification for Ceramic Tile (ANSI A137.1 for caliber ranges). Allowances are more than just tile size; variations include allowable edge warpage, wedging and diagonal warpage based on the tile types such as glazed wall tiles, pressed floor tile, quarry tile, calibrated and rectified porcelain tile. Along with tile type considerations also come modular size considerations; a larger tile may have more allowance than smaller-format tiles.
The tile contractor also has to work with “allowable” variations in subsurface/substrate flatness that he/she intends to install tile over. These are relevant to tile size and specifics can be found in ANSI A108.02, section 4, general requirements for tile installations. Taking all the above variations into consideration, the requirement that the tile contractor produce a smooth, flat, beautiful and durable tile installation is not a small request nor an easy task.
Grout materials provide a means for the tile mechanic in the setting process to adjust the tile layout to accommodate size variations and warpage to a given degree. Grout joint size itself can also be adjusted to help with tile size variations. Pattern adjustments and grout will assist in reducing lippage between tile courses when tile warpage is on the high end of the allowable range.
Tile expands and contracts based on moisture and temperatures — that’s right, even porcelain tile. In fact, all building materials experience co-efficient of thermal expansion based on exposures to moisture and heat. That means interior spaces with direct sunlight, exteriors and materials in wet areas will see the most movement. The American Society of Testing Materials (ASTM) test method ASTM C372 {- 4°F /-20°C to 212°F/100°C} measures linear thermal expansion of modular tile bodies and provides important data for specifying tile usage on projects.
Grout will assist in minor amounts of movement resulting in compression and contraction between tiles during these cycles. Remember, designed movement joints are required in the assembly and provide the primary means of managing these thermal cycles along with an appropriate permanently flexible sealant. Movement joint guidelines can be found in Tile Council of North America’s (TCNA) Handbook for Ceramic, Glass, and Stone Tile Installation, detail EJ 171.
What are the top complaints of grout? Efflorescence and color shading are the always at the top of this list. But why?
ANSI A118.6. Standard cement grouts are still the most commonly used materials on the market. They are easy to mix, apply and clean. Portland cement grouts have been around for many years and worked very well with older-style tile bodies that had an absorption value. The absorption rate of the tile actually assisted in drying times of the Portland cement grouts, even with the larger joint sizes of the time. Because the joints were drying faster from absorption, color consistency wasn’t too much of an issue.
As tile technologies evolved, tile bodies became less and less absorptive, until we reached the porcelain tiles of today that have 0.5% absorption or less and are categorized as “impervious.” That’s great for stain protection and durability of the tile, but it really creates a problem for standard Portland cement grouts that relied on tile absorption to dry quickly, which is what locked in pigments to create color consistency. These delayed drying times, along with wash water, can create the whitish layer we all know as efflorescence. This is actually the migration of minerals from the components within the Portland cement. While this grout category is the least expensive, it carries a risk of potential efflorescence and color variations and is one of the lower performing grouts available.
An ANSI A118.7 lower-performing cement grout has the advantage of being ready for light foot traffic the same day. Its high, early strength and low water absorption are key in allowing this rapid return to service. The nature of these products prevents the long-term emergence of efflorescence and does not rely on assistance in absorption from tile for drying.
Why are contractors and designers switching to high-performance cement grouts? The answer is obvious: low to no call backs due to their calcium aluminate base and chemistries that are compatible with today’s porcelain tile characteristics. There has been a significant wave of “at-home” designers that are looking at their space with a more critical eye. The long-lasting nature of a grout installation causes this particular aspect to rise to their attention. With high-performance cement grouts comes a detectable advantage in vivid color consistency that can live on through a series of design changes.
Not every type of grout is designed to meet the unique requirements of a project. It is important to evaluate the needs of a project based on the type of facility and the service demands affecting the tiling system. Best practices for grout choice also consider the maintenance of the tile assembly. Tile selection, waterproofing, crack isolation membranes and mortar should all be selected using the same process.
The TCNA has created a “Grout Selection Guide” and “Floor Tiling Guide” based on performance level requirements in a selection table, which can be found in the TCNA Handbook. This allows all parties involved to make materials decision based on the facility type, best installation methods and appropriate materials accordingly.
On the previous page is a performance requirement chart based on ANSI standards for each grout showing eight grout choices with nine options. You can clearly see the differences in chemical makeup, strengths and expected performance.
Grout joint sizes have gotten much smaller over the years. Based on surveys, the average size is now only 1/8 inch. For a small joint, used with larger popular tile sizes of 12 x 24 inches and larger, the average project now requires 75% less grout than it would have used just 10 years ago. So, I strongly recommend that you don’t cut costs on the second thing the customer will see when they look at the finished flooring. It pays to use the best grout option available to satisfy the client and ensure long-term floor system performance. Additionally, consult with the grout materials manufacturer to help specify the right grout in the right place and make sure they will back up the installation with a project warranty.
