STEEP SLOPECOMPOSITION SHINGLE
The most common type of sloped roofing in our (San Francisco Bay) area is asphalt composition shingle. A minimum slope of 3:12 (3 rise for every 12 laterally) is usually required for shingle roofing; however there are exceptions.
Typically, composition shingles are an asphalt-based product, bonded to a reinforcing fiberglass mat, with a mineral granular surface. The asphalt provides the waterproofing and the mineral surface protects the shingle from breakdown due to sun exposure. These shingles are produced by various manufacturers with differing warranties and life expectancies. The main factors in the life of the shingle are the amount of asphalt-more is more, and the technology used in bonding the fiberglass mat and applying the mineral surface. Traditionally, manufacturers have supplied their products with limited warranties; 20 year, 30 year, 40, 50 and so on. More recently, limited lifetime warranties have become the norm, with our understanding of lifetime being as long as you own the house. Sometimes a homeowner is allowed to transfer the warranty to a new owner. Extended or premium warranties are also often offered. If manufacturers warranties are important to you, we recommend getting full information directly from their website or printed information. Composition shingles have been around for many decades; they are a proven product with an excellent track record, are relatively easy to install, and offer a robust lower-cost roofing option. A correctly installed composition roof will have a
class-A fire rating and will be available in a wide range of shapes, styles, and colors.
LIFE: 25-50 years
WOOD SHINGLE and SHAKES
Wood shingles and shakes provide a traditional and naturally good-looking roof. They have been common in many parts of the country where wood products were readily available and relatively inexpensive. However, the cost of these products has risen significantly over the past 30 years, while the quality seems to have diminished. We used to think of wood roofs lasting 30-40 years, but are increasingly seeing roofs needing replacement at 20 or 25 years. Possibly this is because shakes and shingle are no longer available from original so-called old-growth trees, rather they are produced from farmed stock, which are harvested younger and do not contain and the protective oils present in older trees. Increasingly, municipalities have banned or limited wood roofs due to potential fire hazards. Insurance companies also tend to frown on wood roofs, and have been known to require a change to a class-A assembly to continue their insurance coverage.
LIFE: 20-35 years
Mediterranean (or Spanish, or Mexican) clay tile roofs are one of the most beautiful and long-lasting roofs available. Tile roofs have been around for hundreds if not thousands of years. These roofs fall into two groups; traditional two-piece (cap & pan) and a more recent one-piece (S-type). The underlayments or base sheets for these roofs, and indeed for most roofs, has changed over time with the development of long-lasting synthetic products, but the installation technique has remained the same. In a two-piece assembly, the bottom (pan) tile is secured to the roof deck with a copper nail and the top (cap) tile is also secured to a copper nail with copper wire that passes through a small hole at the top of the tile. The hole is then covered with the next of tiles. At the top, hip and ridge tiles are set into a mortar bed. Bird-stop- small clay tiles or shaped metal is often used at the eaves to fill the area below the cap-tiles and discourage birds nesting. Copper valleys, along with copper and lead flashings, are often associated with mission tile roofs. A well-installed cap & pan tile roof should last 70-80+ years. Usually, when we re-roof these assemblies, we change the base sheets to a more modern synthetic and re-install the original tiles. Often these tiles are hand-made with the hand and fingerprints of the original artisan still visible. One-piece or S-type tiles are a more recent development and have a similar installation as composite roofs.
LIFE: 60-90 years
COST: $850-$1,200 with existing tile
Slate is also a product that has been used for roofing since the time of the Romans. A higher-end product, it is also often associated with copper valleys and copper and lead flashings. Various base sheets are available and the lay-up is quite straightforward. However, the technique of handling and installing slates can only be learned by experience and we have seen many installations where the skill set was not up to par. Slight variations in the color of natural slate can make for a very interesting variegated look if installed correctly, but random placement or blending can be very challenging. Experience is the key factor. Lighter colored slates tend to be more expensive than darker. Slates come from many areas of the world, most notably from Europe, Mexico, and increasingly from China.
LIFE: 80-100 years
Composite tiles and shingle-as opposed to composition shingles-refers to shingles made out of various ersatz materials, such as: fiber-cement, concrete, plastics, recycled tires, etc. Introduced in the 1930s, the earliest composite Transite products proved to be successful and long lasting. However the asbestos content in this products-although not very high-led to Transite being largely phased out by the 1970s. Various other composites have been developed and used with varying degrees of success (and failure). Composites are usually molded or pressed products, which come in many shapes and are usually designed to look like tile or slate. Wood shake look-alike composites are often used as an alternative to natural wood shakes when a class-A fire rating is required. Concrete and lightweight concrete tiles are also popular.
LIFE: 20-50 years
METAL SHINGLES AND STANDING SEAM / PBR / CORRUGATED
Galvanized (corrugated) steel, aluminum, and steel with (or without) powder-coated paint finish, zinc, and copper are all available as roofing materials, either as shingles or as roof panels. The conductive properties of metal usually require that a heat resistive base sheet be installed. In hotter areas a gypsum heat barrier may be worth considering. Standing seam roofs have become increasingly popular over the last few years. They provide a clean modern look and are relatively simple to install. As they have become more widespread, they are one of the very few assemblies that have actually come down in price!
LIFE: 40-90 years
COST: $500-$1,100 Standing Seam: $700-$1,000