People who own slate-roofed houses often have a mystery — and a problem — on their hands.
That slate roof looks great, adding an air of elegance to the house. It has lasted 100 years or more. But it leaks.
Sometimes the roof will leak in several places during a rainfall. Then a week later during another rainfall, the leaks are somewhere else. Now, that is a mystery.
So the owner calls a roofer, who says, “Beats me,” and suggests ripping off the slate and putting up asphalt. Trying to repair a slate roof is not only difficult but very expensive, the owner is told.
One problem with this scenario is that the owner called the wrong kind of roofer. He should have checked with a slate specialist, who might say that he can repair the roof without busting the budget.
Homeowners, even those whose roofs are slate, don’t know much about slate, and might be hard put to find much about it. There is very little “literature” about it.
Until now.
Two new books tell us all about slate. One is “The Slate Book” by Brian Stearns, Alan Stearns, and John Meyer, who work for Vermont Slate & Copper Services of Stowe, Vt. They are members of the National Roofing Contractors Association, North/East Roofing Contractors Association, Roofing Consultants Institute, and Construction Specifiers Institute.
Subtitled “How to Design, Specify, Install and Repair a Slate Roof,” the book is self-published by the authors and has a rather hefty price of $79.95.
It is a how-to manual, with a wealth of information on what slate is and what it will do, and there are many illustrations.
The other book is “The Slate Roof Bible” by Joseph Jenkins, who is a slate specialist and repairer who lives in western Pennsylvania. Also self-published, the book has a more reasonable price, $35. It is distributed by Chelsea Green Publishing of White River Junction, Vt.
The subtitle is a mouthful: “Everything You Wanted to Know About Slate Roofs Including How to Keep Them Alive for Centuries.”
Among the many people who helped Jenkins gather information is Doug Raboin, who heads the Twelfth Century Slate Roofing Co. in Burlington, Mass.
The books have common themes: Slate can last for up to 400 years and beyond, and should remain on the roof in most cases, and that repairs can be much less expensive than many people, including slate roof owners, think.
While both books provide an ocean of information, Jenkins tells his tale with pizazz and rollicking humor, offering anecdote after anecdote about what people do, and do not do, to their slate roofs.
For instance, a woman wanted to trash her slate roof and put on a brown roof so it would match the curtains. Jenkins tried to talk her out of it, but failed, although he has convinced many slate owners to keep their roofs. He even offered to remove the slate for free. And failed.
Slate roofs are not uncommon. Just look around, in the cities particularly, and you will find them on old houses, mostly, and big ones, usually. And, of course, cathedrals and churches galore.
But what is slate? It’s a stone that is quarried or mined. Jenkins says there are three kinds: mica, clay, and igneous, but mica is the only type that is used for roofs.
And how old is it? Millions of years. In fact, “Peach Bottom” slate, a popular, hard slate mined in Pennsylvania, was formed 600 million years ago. That’s a lot older than the dinosaurs, writes Jenkins.
Where does it come from? It used to come, during its heyday early in the 20th century, from states on the Eastern seaboard: Maine, Massachusetts, New York, New Jersey, Vermont, Pennsylvania, Maryland, Virgnia, and Georgia, and also Tennessee, Arkansas, California, Colorado, Minnesota, Utah, and Nevada.
Today, slate comes primarily from Vermont, New York, Pennsylvania, and Virginia. The decline in production is not due to shortage of materials — many mines are still largely untapped — but simply because roof slates are expensive to produce.
There are also different grades of slate. Generally, the harder the slate, the longer it lasts, up to 250 years and even 400 years. On some roofs, no one knows how long the slate will last.
Most slate quarried in the U.S. today is hard, but only your slate roofer can tell you about the slate already on your roof.
Slate is heavy. A slate just 3/16-inch thick weighs 700 to 750 pounds per square (100 square feet), which means it weighs 7 to 7 1/2 pounds per square foot. At the high end of the scale, a two-inch-thick slate weighs 8,000 pounds per square, or 80 pounds per square foot. The heavy weight of slate means that the frame that the slate is going on had better be pretty sturdy.
Both books devote a lot of time and pages to installing and repairing slate. The slates are punched for nail holes, and the holes are beveled so the nails heads will be flush with the surface rather than sticking up above. If the latter happens, you will get a lot of broken slates.
And, an important point: Slate is hung on the roof with nails. In other words, nails are not driven home; if they were, the slate would break.
Another point that the authors of both books make is that you can repair slate roofs, or have them repaired, usually for a lot less money than a new roof would cost.
You can face-nail a slate and caulk the nail head, for instance, or even replace individual slates.
What else is there to slate roofs? Plenty. All you have to do is read the books.
And the best advice to anyone, any time: If you are skittish on a roof, stay off. Let the pros do it. And never walk on a wet slate roof. You don’t see many live roofers working on a wet slate roof.
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The books may be in bookstores. If not, you can order “The Slate Book” by writing to Vermont Slate & Copper Services Inc., PO Box 430, Stowe, VT 05672, telephone 888-766-4273.
For “The Slate Roof Bible,” write to Chelsea Green Publishing, PO Box 428, Whtie River Junction, VT 05001, telephone 800-639-4099 or 802-295-6300.
