Installing a Lightweight Slate Roof

Installing a slate roof has remained fundamentally the same procedure for over two century’s. Up until the last ten years or so, there was really only one way to install a slate roof. This was the traditional triple overlap method with two nails for every piece of slate. Since slate is a free-floating roof material, the pieces actually “hang” from the nails compared to being firmly nailed down into place. This allows for less rigidity, improved walkability, and better breathability, which is vital for proper roof ventilation. However, in the past decade, the need for a lightweight slate roof system has become ever more apparent. Typically, the weight of a slate roof requires the re-engineering of the entire roof structure to safely support the stone. Engineering and structuring can be very costly and simply are not in everyone’s budget. So in the past decade the objective has been to make a product that captures all the timeless qualities of a slate roof, while maintaining a reasonably low roof weight. Most roofs that weigh less than six hundred pounds per one hundred square feet (one square) are deemed light enough to require no additional structuring or an engineering report. This is where the many new variations of lightweight slate roof systems come into play. In general; there are two ways to achieve a lightweight slate roof. One, there are the lightweight slate systems that reduce the amount of stone actually going on the roof to lower the weight, and two, there are the synthetic faux slate products (polymer).

In the first category, there are several products on the market that reduce the roof weight with real stone, using a number of very different techniques. A SlateTec roof falls into this category; being a patented lightweight system that takes advantage of natural stone, while reducing the overall amount of stone that’s going on the roof to under six hundred pounds per square. The SlateTec system employs the most simple, traditional installation technique of all the lightweight systems. At SlateTec Inc we believe that with most things in life, the simpler something is, the longer it will last. Our roof system is as close to the well-known traditional installation process as they get. Most notably, we use the traditional free-floating nail down method that has proved itself since slate was first put on roofs. Aesthetically speaking, there is absolutely no difference between a traditional slate roof and SlateTec. The only real difference between a traditional slate roof (besides weighing ~ 40% less weight) and the SlateTec Inc system is the patented signature interlayment that is woven into every course of slate. It is as easy as laying the interlayment over each course and nailing it down as you go. The high-tech, durable interlayment is a time tested HDPE product that has been on telephone cables and used as landfill liners for over fifty years. It replaces the slate that is normally hidden on a traditional install (water barrier for side laps), allowing for the use of smaller pieces of slate that are closer to half the length of traditional pieces. This makes for much easier roof loading, slate handling, and most importantly a lower overall roof weight. A SlateTec roof is installed from the bottom up and there is no starter course needed with the system. All of the metal work is similar to that of a standard application. We have found that once consumers are aware of the lightweight aspects of the SlateTec system and actually install a SlateTec roof, there is literally no turning back. There really is no reason to make a lightweight slate roof system any more complicated than it has to be.

At the same time, other lightweight systems tend to do just that and over complicate the installation. They require a tremendous amount of time devoted to training and practice by the crew to get it right. For example, one of SlateTec’s biggest competitors uses less overall slate by implementing a hook, rail, and batten system with smaller than traditional pieces of slate. The installer must first put down the hook and rail arrangement on the roof for every course of slate, then slide each piece of slate into its designated spot and seat it on two hooks. The piece of slate is then hanging by two wire hooks off the roof deck in this batten and rail system. The pieces have to be installed from the top of the roof down as they are not very walkable once they are hooked in. Also, this system makes it’s difficult to achieve a staggered and/or random width application, which is what slate roofs are known for. These types of systems are a far cry from the traditional installation process, traditional aesthetics and are complicated to say the least.

The synthetic products are essentially polymer molds of a piece of slate that try to mimic the aesthetics of natural stone. They have a few advantages, such as being able to use a nail gun upon installation, similar to asphalt shingles. However, they do have their flaws. The pieces have been known to fade, warp, crack, curl, and basically fail over time. The only way to fully capture the timeless natural beauty of slate on a roof is to use the real stone. At SlateTec Inc we offer a lightweight slate roof option that is easy to install, uses the highest quality of genuine stone and is unrivaled aesthetically.