Types of Roofing
The most common types of roofing materials for residential structures are: asphalt shingles, wood shingles and shakes, metal roofs, tile, slate and composite coverings.
ASPHALT ROOFS: This is the most commonly used and least expensive roof covering material. Asphalt roofing materials consist of either a rag fiber or a fiberglass mat impregnated with asphalt and covered with colored mineral granules. A wide variety of designs, weights, colors and sizes are available.
Asphalt roofs show their age when the mineral granules wear off, reveal the black asphalt and the corners and edges of the shingles begin to curl and crack. This is an indication that the asphalt composition has begun to dry out and lose its weather-proof seal. When only a few shingles show the above type of wear, the simple and less costly replacement of worn out shingles may be all that is needed. If one out of every five to ten shingles shows this wear and aging, it is may be time to re-roof.
WOOD SHINGLES AND SHAKES: Shingles made of cedar, cypress or red wood are highly rot-resistant and may last 30 to 35 years if properly installed and maintained. The best wood roofing materials are pressure-treated with wood preservatives. When considering home safety, it is wise to note that wood shingles and shakes are more highly combustible than the other roofing materials available. If a wood shingle is your choice, look for one treated with fire-retardant chemicals.
As wood shingles and shakes age they may shrink and form gaps between each shingle. They may also become brittle and offer less protection from the elements. As is the case with asphalt shingles, if only a few wooden shingles show this wear and tear, replace the individual shingles.
METAL ROOFS: Metal roofs are highly resistant to damage from the elements and may frequently last 40 years or more. They are highly fire resistant and require little maintenance. Small damaged areas can be repaired with patches of similar metal. The materials used in a metal roof may include copper, tin, steel, aluminum, lead or an alloy combination of one or more of these metals.
TILE, SLATE AND COMPOSITES: Roofs made of slate or tiles composed of either clay or concrete are perhaps the longest lasting available. They frequently survive more than 50 years, and normally require little or no maintenance. In addition these materials are extremely fire resistant. When one of these roofs does need replacement, however, the cost can be very high.
Tiles offer comparable benefits to slate but come in a more decorative and cosmetically-pleasing variety of colors, textures, shapes and sizes. Tiles can be glazed or unglazed. Slate typically comes in only black, grey or dark red.
Types of Roof Coatings
Roof coating has become an effective and popular method of extending the life of a roof. It can add protection against weather and fire, may increase energy efficiency and can even be used to change a roof’s color. But is is no substitute for repairs to a defective or worn out roof. Consequently, roof coatings should be applied before any serious roof deterioration occurs.
Maintenance roof coatings or cold process roof coatings are ready-to-use protective coatings for roofs and other areas exposed to the elements. They come in a liquid or semi-liquid state and are applied by brush, roller or spray. Roof coating professionals generally use coating materials that can be grouped into the following five categories:
ASPHALT-BASE COATINGS: Asphalt-Base Coatings come in three different types: emulsion, solvent or aluminum pigmented.
• Emulsion Type Coating is adaptable over asphalt built-up roofs, metal roofs and those similarly composed, provided there is adequate drainage. When applied in the proper thickness, it chalks slowly and doesn’t blister. It can be applied over a damp surface and will not flow under heat. It does require temperature and humidity conditions that permit thorough water evaporation before the coating can be subjected to rainfall, freezing, or standing water. Emulsion coating requires a clean and a primed surface for good adhesion.
• Solvent Type Coating can be applied over asphalt, composition, asbestos-cement, metal and masonry roof surfaces. It can be applied on a clean, dry surface over a wide temperature range and is relatively free of wash-off problems after a short drying period. It has good water resistance and may not require a primed surface for good adhesion. Solvent coating may flow under extreme heat and is combustible. It is susceptible to blistering if applied over a damp surface or any material containing moisture.
• Aluminum Pigmented Coating consists of flake aluminum particles dispersed in solvent type asphalt coatings. It can be applied over asphalt, composition or metal roofs having adequate drainage and provides a reflective or decorative surface. The coating’s reflectivity helps improve a buildings energy efficiency by deflecting ultraviolet rays and reducing the roof’s temperature. The cost of this coating is higher than most and its applications over low melt asphalt roofs can result in discoloration and scaling. It is susceptible to blistering if applied over a damp surface or any material containing moisture.
ALKY-BASE COATINGS: Alkyd-base coatings can be applied over metal, composition or masonry roofs that have adequate drainage. They perform the same functions as aluminum pigmented coating. Although alkyd-base coatings cost more, they are often selected because of their decorative versatility. They will not flow under heat and are susceptible to blistering if applied over any damp material. Alkyd-base coatings tend to discolor and/or split when applied over low melting point asphalt and are combustible.
• Acrylic Latex Coating: Acrylic latex coating comes in liquid form and is available in various colors; white being the most common. White and other light colors reflect the sunlight, keeping the interior of a building cooler and conserving energy during warmer months.
• Refined Coal Tar Coating: Refined coal tar coating is used for re-coating tar and gravel roofs. In preparation, the gravel must be removed and roof surface broom cleaned. Proper protection requires approximately seven gallons per 100 square feet, and gravel should be re-applied over the coating. It is self-heating at warm temperatures, is very water resistant and can be used where the roof is subject to standing water. Refined coal tar tends to be brittle in cold weather, and its use is restricted to relatively flat roofs.
• Flexible Ceramic Coating: Flexible Ceramic Coating is a relatively new addition to the roof coating business. The primary attraction of a ceramic coating is its insulation properties that allow for energy efficiency. As a result of its flexible nature, ceramic coatings help seal cracks and hide surface flaws. It has proven particularly popular in warmer climates.