Material often defines the architecture not just of bridges and skyscrapers but even of the most common American houses. Federal homes are brick in the South, wood- frame and clapboard in the North. International Style is concrete, and Shingle Style speaks for itself. But what of Arts & Crafts buildings?

Even if you live in a house from the bungalow era, chances are your roof is covered in asphalt. Nothing wrong with that: at $1 to $3 per square foot, the ubiquitous asphalt shingle is by far the most affordable roof you can buy.