Artificial slate and shakes fall into the common category of shingle products in that they are steep-slope roofing products overlapped to shed water to the edges of a building.
There are many demands on shingles. To function successfully, they must be shaped and oriented to shed water reliably. Shingles also must be durable so they can be safely installed and maintained throughout their expected life spans, resist wind and perform effectively under local weather conditions. And because most steep-slope roof systems are visible, shingles must be attractive, retaining their desired appearance throughout their expected life spans.
The history of artificial slate and shakes made from fiber-reinforced cement is a mix of success and failure. But this is not surprising when you review how the changes occurred within the industry.
What Happened
Before the 1980s, most artificial roofing slate was made from asbestos-cement, a material that had a long track record of successful performance. When the use of asbestos became forbidden, manufacturers rushed to replace asbestos-containing products with cement-based products reinforced with non-asbestos materials.
Products were quickly introduced into the marketplace with little research and development relative to the products’ desired life. Products that looked “good” when tested shortly after they were manufactured were produced, delivered and installed without studying the long-term effects of weathering on the material properties.
As a result, these materials experienced extensive failures during the early 1990s, well before the end of their intended life spans, which often were advertised to be 30 to 50 years. Roofing contractors and building owners became unwitting research agents for the new artificial slate replacement products. When it became clear there were fundamental problems with these materials, contractors and owners were met with neglect, denial, inappropriate counterclaims and lawyers by the manufacturers.
Virtually every product introduced during the 1980s and 1990s has been pulled from the market and is, fortunately, no longer available.
The current generation of artificial slate and shakes is based on rubber and plastic technology. Current products look realistic and are attractive when installed. Although the rubber and plastic industries have made single-ply roofing materials that have successfully withstood the test of time and outdoor weathering, current plastic and rubber slate and shakes do not have track records to match their warranties.
Roofing contractors have a legitimate expectation that the goods they purchase on behalf of their customers are fit for their intended purposes. What follows is a summary of years of research we performed that demonstrates slate and shakes manufactured from fiber-cement materials reinforced with cellulose fibers were doomed to fail from the start. Fiber cement made from wood fibers, newsprint, wood chips and combinations of these materials did not stand up to the test of time. |
