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Long the pride of homeowners by virtue of its beauty, stability, and longevity, slate reached peak popularity as a roofing material around 1915. As early as 1906, though, manufacturers were already experimenting with man-made alternatives, such as asphalt shingles and asbestos-cement slates, that could be made lighter, cheaper, or easier to install. The search for the perfect slate substitute continues today. The choice of products grows wider every year, while the list of manufacturers changes annually as new players enter the market and old ones leave. Since modern slate substitutes may be one of the options for old-house owners replacing or extending a natural slate roof-or an ersatz slate installation from, say, the 1930s that is now historic in its own right-OHJ has put together the following buyer's guide to help sort out the many products, materials, and makers that represent the state of the art in this evolving industry. Simulated Slate Suitability If you must reroof an old slated house, by all means do so in slate when possible. If enough of the slate is still in good condition (see "Slate Weathering," May/June 2002 OHJ) consider removing it, repairing the underlying sheathing and flashing, then reusing the good original slates on the principal roofs-that is, the ones that show. You can then use new slate or a substitute on the rear or subordinate roofs. After a shaky start, simulated slates are finding growing acceptance for restoration projects because of better quality replicas and good performance on historic buildings in Europe (where they have been extensively used for several decades). Though these are still substitute materials as defined by the Secretary of the Interior's Standards for Rehabilitation, some of the better products have garnered cautious federal government endorsement for preservation use. Sharon Park, FAIA, senior historical architect for the National Park Service Technical Assistance Division, recommends checking with your local historical commission, if there is one, and with your State Historic Preservation Office concerning the appropriate substitute slate for your project. This is obligatory if you hope to cash in on tax credits for home rehabilitation in states that provide them. Losing the character and patina of an old slate roof is always regrettable,
but Park acknowledges that there are circumstances when a new or man-made
roof becomes necessary. Regarding replacement materials in general,
the National Park Service stresses that they "be compatible with
historic materials in appearance." As outlined in Preservation
Brief number 16, "The Use of Substitute Materials on Historic Building
Exteriors," the new, substitute material "should match the
details and craftsmanship of the original, as well as the color, surface
texture, surface reflectivity and finish of the original material. The
closer an element is to the viewer, the more closely the material and
craftsmanship must match the original."
The latest breeds of simulated slates come in several quite different materials, from the old standard concrete tiles to new ceramics and recycled rubber. Fiber Cement This is the oldest type of substitute slate (and also of wood shingles), dating in its original form to the first decade of the 20th century. Modern versions, made with nonasbestos cellulose or man-made fibers, have wide use on roofs, on mansard dormer cheeks, and as siding. Most fiber-cement slates bear close resemblance visually and physically to the real thing. Manufacturers may specify the use of storm anchors. A major consideration is that installation labor costs are roughly the same as with real slate, making the lower material cost the only savings. Concrete Tiles Concrete slates have been around for a long time but aren't as well known as other materials. They employ basically the same binder (cement) as fiber-cement slates but leave out the fiber component. Instead, they are made like concrete, with aggregates (such as sand and perlite) and sometimes metal reinforcement. The resulting slate is thicker than fiber cement and very heavy-sometimes more than 1,000 pounds per square. For that reason, concrete often requires heavier than usual roof framing and is less than desirable for steep slopes. Concrete slates require special installation in areas subject to 125 mph winds. Clay Tile The most promising among the newer forms of roof tiles, slatelike and otherwise, clay tile is hard and strong, with integral color or glaze color. Much used in Europe, it is rapidly gaining ground in the United States. There are some color limitations, and the product does not have the irregular edges of true slate. The tiles are generally interlocking. Asphalt Shingles The standard house roofing, made for a century in one formulation or another, asphalt shingles are affordable, efficient to install because they come in strips, and available in almost endless variety. In recent decades, the industry has moved into making what are called architectural or laminated shingles. These employ two or more layers of roofing material to produce a more textural effect with softer lines and deeper shadows. First popular in wood-toned shingles, these techniques have been turned to emulating the appearance if not the actual form of slate roofing, with appropriate colors and shadow lines. An added benefit of some of these products is that they are thicker and therefore longer lasting than the standard three-tab strip shingle of yore. Many companies now make asphalt slatelike shingles-none perfect imitations but all relatively inexpensive and easy to install. Recycled Rubber The latest class of competitors in the slate lookalike market are composed of recycled rubber (from industrial waste to automobile tires) and polypropylene. Most are updated, slatelike versions of the time-tested asphalt shingle, following in the path of wood-toned architectural asphalt shingles. The materials are too new to comment on life span, but their light weight and slight flexibility are good news. Each product generally strives to look like slate, with realistic surface textures, chipped edges, and authentic colors. Compared to real slate, they are also relatively inexpensive. Manufacturers claim the roofing is good in high wind conditions. Slate/Resin Composites Another new and promising material, pioneered so far by just one manufacturer, is best called a composite slate. This product is an amalgam of likely components-ground slate, resin, and fiberglass-bonded under high pressure to form a realistic-looking slate substitute. The process produces good modeling of the irregularities of slate itself with integral color and typical unit sizes, paired with the appeal of light weight. Examine several kinds of man-made slate to choose the best material and color for your use. You may decide that the slate look isn't for you at all, in which case the firms that make slate reproductions also make wood-grain and various tile repros as well.
Re-Con Building Products Auburn Tile, Inc. Columbia Concrete Products Monierlifetile Richmond Precast Concrete Products Vande Hey- Raleigh Celadon Gladding McBean Crowe Building Products EcoStar Royal Building Products Welsh Mountain Slate, Inc. Certainteed Elk GAF Materials Corp IKO Owens Corning |
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