What most homeowners desire is a roof that's not too expensive, requires no maintenance, and lasts forever. But most roofs are replaced - or at least repaired - every ten years. By carefully choosing your home's roofing material, you can reduce the cost of replacement. In the long run, you'll use less building material, fill up less landfill space with discarded material, and put less demand on our natural resources.

You can realize energy saving benefits from your roofing choices. If you select a light-colored surface or a material that doesn't absorb heat from the sun, you significantly reduce your home's cooling needs. When your attic stays cooler, your cooling bills go down.

There is a wide choice of materials used to roof a house, ranging from composition shingles, to slate - pieces of stone. Modern products like plastic, fiberglass and concrete are available, and some innovative, energy-efficient homes are being roofed with sod. New products are being developed to overcome the shortcomings of older roofing materials, meet the demands of modern building techniques, and conform to increasingly stringent building codes.

Popular Roofing Materials

Here is a rundown on the most popular types of roofing. Remember that cost alone does not determine quality, and not all of these products will meet the needs of your home. But by carefully selecting the right material, making sure it's installed properly and performing modest maintenance occasionally, you can have a roof that functions properly for 20 to 50 years - or even longer.

· Metal roofs are coming back into vogue. In the late 1700s, zinc, copper, and lead were the most popular materials used for roofing - such famous historic buildings as the Washington Monument and Thomas Jefferson's Monticello have metal roofs.

Standing-seam steel roofing is the most popular residential metal roofing today. (The term standing-seam describes the upturned edge of one metal panel that connects it to adjacent sections, creating distinctive vertical lines and a trendy historical look.) But metal roofs can also be made to resemble wood shakes, clay tiles, shingles, and Victorian metal tiles. Aluminum or coated steel is formed into individual shingles or tiles, or into modular panels four feet long that mimic a row of shingles or tiles.

Metal roofs are durable, fire retardant and almost maintenance-free. They are also energy efficient; metal reflects heat and blocks its transfer into the attic. Research by the Florida Solar Energy Center in 1985 showed that metal absorbed 34 percent less heat than asphalt shingles, and homeowners switching to metal roofing reported saving up to 20 percent on their energy bills.

Steel roofs offer other environmental benefits as well. They are made from between 60 percent to 65 percent recyclable material. Because they weigh very little, metal roofing can be installed over existing roofs, eliminating the need to dispose of excess material in a landfill.

Installing some metal roofing can be an intricate process best done by a professional, and the initial cost of a premium metal roof is higher than most other roofing materials. You need to compute the lifecycle cost to see if paying more to begin with for a metal roof will prove to be a better investment than some other form of roofing.

Mostly seen in commercial applications, hot mopped asphalt roofing is sometimes applied to flat or semi-flat residential roofs that have good access and proper drainage. Asphalt's advantage is that it is less expensive than other roofing materials and holds up fairly well when properly applied. The technique results in a roof that's not very pretty, although in residential use it is often covered with a layer of decorative stone to improve the appearance.

You've no doubt noticed roofing projects that use this technique, since it requires a large kettle of melted asphalt. When being applied, the hot mixture releases extremely high levels of smelly air pollutants. In addition to being unpleasant, the hot asphalt poses a health risk to installers. Because its fumes contribute to smog, hot mopped asphalt may be restricted in some urban areas.

· Composition shingles are a good choice for a clean look at an affordable price. Higher-quality versions made from asphalt or fiberglass shingles offer a more durable option and may be available with recycled content.

Composition shingles come in a large selection of types, brands and colors. Versatile, they adapt easily to different applications. They are relatively easy to install, and in some applications can be nailed in place over an existing roof. They require low maintenance and can be walked on without damaging the material. Most brands offer Class A fire protection.

On the negative side, composition shingles don't have the life span of other materials like tile or metal. They don't offer the dimensional look of tile or wood shakes, and they can blow off in high winds.

· Wood shakes offer a natural look with a lot of character. Because of variations like color, width, thickness, or cut of the wood, no two shake roofs will ever be the same.

Wood offers some energy benefits, too: it helps to insulate the attic, and it allows the house to breathe, circulating air through the small openings under the felt rows on which wooden shingles are laid.

A wood shake roof, however demands proper maintenance and repair, or it will not last as long as other products. Mold, rot, and insects can be a problem. The lifecycle cost of a shake roof may be high, and old shakes can't be recycled.

Most wood shakes are unrated by fire safety codes. Many use wipe or spray-on fire retardants which offer less protection and are only effective for a few years. There are pressure-treated shakes, however, that are impregnated with fire retardant and meet fire safety standards. This pressure treating extends the life of wood shingles and provides better fire safety performance.

Installing wood shakes is more complicated than roofing with composite shingles, and the quality of finished roof depends on the experience of the contractor as well as the caliber of the shakes you use. The best shakes come from the heartwood of large old cedar trees, difficult to find any more. Some contractors maintain that shakes made from the outer wood of smaller cedars - the usual source today - are less uniform, more subject to twisting and warping, and don't last as long.

· Roofing tile is a good choice for homes with a southwestern, Italian, or Spanish Mission design, or even for homes with a modern, clean look.

Tile lasts a long time - its expected lifespan is greater than the lifespan of the material on which the roofing rests. Tile won't rot or burn, and it can't be harmed by insects. It requires little maintenance, and comes in a variety of colors, types, styles and brands.

The biggest drawback to tile is its weight. Depending on the material used to make it, tile can be very heavy - so heavy that extra roof support can be required. Originally made from clay, new tiles are being made from lighter materials, and lightweight metal tiles can be installed over existing roofs. With some new materials, however, color is added only on the surface of the tile, and they can fade over time.

Some types of tile are fragile, so walking on them can break them. That makes it more difficult to accomplish maintenance like painting or cleaning rain gutters or fireplaces. Initial installation can be complicated.

Finally, tile can cost more than other roofing materials.

Slate - actual shingle-like slivers of rock - is another roofing material that shows up on more upscale homes. Although slate is an expensive choice, it offers a very natural look and can be laid out in a variety of patterns.

The benefits of slate are identical to those of tile: a very long lifespan, good fire protection, low maintenance, and an invulnerably to rot and insects. It comes in a good selection of sizes and colors, although colors are limited to those found in nature.

Like tile, slate can be very heavy, sometimes requiring expensive extra support. It, too, is breakable enough that walking on it is difficult for a non-professional, complicating such tasks as rooftop maintenance, gutter cleaning and painting.