Lightweight mortars offer up to twice the coverage per pound. With smoother consistency than traditional mortars, lightweights require less physical exertion in troweling. Installers benefit from reduced fatigue.

If you’re a tile contractor, you’re working in an industry not only steeped in ancient tradition but sparked by modern appreciation for tile’s beauty and durability. In the thousands of years the tile setting profession has existed, the basic components of the job-the tile, the tools, the setting materials-have experienced relatively little modification overall. However things tend to change more rapidly in today’s high tech world, and this is true even for the time-honored tradition of tile setting-specifically, for the category of mortars.

Spurred primarily by the increased use of tile, evolving construction practices, the rising cost of fuel and ever-improving technology, manufacturers have created new, lightweight mortars. The marketplace has demanded innovation; installers are reaping the rewards.

Lightweight mortars represent the future of the industry. With formulations developed with advanced technology, manufacturers have achieved a new standard in mortars-lightweight, yet high performance. This generation of mortars weighs up to 50% less per bag in many instances-yet provides the same coverage and installation performance as traditional mortars.

Typical traditional mortars come in 50-pound bags. Lightweights come in at 30 pounds or even as low as 25 pounds in some instances yet offer the same coverage as their heavier predecessors. Reduced weight per bag provides obvious advantages for users: less heavy lifting, less bulk in inventory or on work trucks, even possible reduction of fuel costs with lighter truck loads. Installers benefit from up to twice the coverage per pound of mortar.

Additionally, the lighter weight is also helpful when load factors are a concern in construction. Large format tile and stone have gained popularity, as has the use of wider joist spacing in construction. Lightweight mortars aid in reducing the load per square foot and are extremely non-slumping for floor applications and non-sagging on walls.

As a matter of fact, lightweight mortars have proven to perform very well, maintaining exceptional application characteristics in the full range of standard ASTM and ANSI testing, including point load assessments. Most notably, many lightweight mortars are shown to perform exceedingly well in the Robinson Test-also known as the ASTM C-627. This particular test is used to gauge durability of a full floor system. Installations utilizing quality lightweight mortars ultimately achieve the highest performance levels, with substantial strength developed within a week or less.  

The high performance levels of these new mortars make them ideal solutions for the challenges of wall tile installations. Some lightweight alternatives avoid sagging even when used to set the popular large formats on walls. The ability for the mortar to avoid sagging means that tile set on walls will not slide, instead holding securely in place where it is installed. Comparatively, traditional mortars do not hold tile in place, and installers must make temporary accommodations/fittings to hold tile in place until the mortar cures.

What makes these products perform so well yet weigh substantially less? While traditional mortars-thin-set and mud bed-are comprised primarily of sand (heavy silica or limestone particles), lightweight mortars are formulated with hollow particles that are lightweight and innately enhance bond strength.

This demonstration reveals the exceptional non-sagging characteristics of many lightweight mortars. On the left, the large format tile set with a high-performance lightweight mortar holds strong, while the small tile set with traditional mortar immediately starts to slide. The demonstration goes on to show the small tile falling off completely, while the large tile remains set in place with no sagging at all.

The great news for installers is that the hollow particles in the formulation also make the mortar significantly easier to trowel. The spherical particles in lightweight mortars essentially create a ball bearing effect that minimizes effort required during spreading. With a smoother, creamier consistency, the lightweight products lessen the amount of physical exertion required during installation.

A tertiary benefit of the new lightweight formulations is extended ‘open time’-the amount of time the mortar retains adhesive properties after spreading. The new lightweight mortars stay “tacky” longer, enabling installers to distribute mortar over a larger surface area before setting tile. Likewise, lightweight products promote “full contact” with the tile being set, ensuring complete coverage with less effort required by the installer. These benefits lead to enhanced efficiency and productivity.

As is often the case as a new generation of product hits the market, availability of lightweight mortars was, at first, limited. While pockets of innovators and visionaries sought out the new technology, products on the market were predominantly for special uses and niche applications. Now, as the technology has taken hold, manufacturers have a range of lightweight products-offering progressive formulations to fit any installation need. The market offers lightweights that provide varying degrees of bond strength to meet any application need, and options exist that provide crack isolation as well.

Also of increasing importance in the industry, most lightweight formulations include recycled materials, which helps contribute to LEED certification and gains the favor of environmentally conscious builders, facility managers and consumers.

Offering great efficiencies throughout the supply chain, lightweights are truly the future of mortars. They answer the growing demand for environmentally sound alternatives, and they are installer-friendly.