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About Roofing Materials
Roofs keep out the weather. They need to be fire resistant and withstand the damaging forces of wind, rain, ultraviolet light and other natural elements while maintaining a visually pleasing appearance. In selecting material for roof covering one should take into account its weight (heavier material requires larger support members), its durability (e.g. how well can it tolerate high and low temperatures and for how long), its effect on water falling on the roof, especially if the water is being captured (for example, will gravel from shingles build up sediment in a cistern or do roof materials leach into the water?), the heat-holding qualities of the roof material (does it heat up and stay hot into the night?), as well as cost, fire rating, maintainability, and installation characteristics.
Notes on Roofing Materials**
Recyclability An estimated nine to ten million tons of non-recyclable roofing waste is sent to U.S. landfills each year. To sufficiently reduce the negative environmental impacts of roofing materials, ensure that the roofing manufacturer has a recycling program before purchasing so your roof can be recycled at the end of its use.
Light colored materials: Roofing materials should be light colored in order to improve the albedo of your roof surface, which reduces cooling costs, thermal gains and energy consumption by reflecting the sun's rays. Improving the albedo of your roof surface can cut cooling costs by up to 50%.
| Clay Tile |
Fiber Cement |
Green (Vegetated) |
Lead-Free Metal |
Rubber |
Slate |
Wood |
Clay Tile Roofing
CSI Division: 073213 | Residential Category: Clay Roof Tiles
A durable, attractive material that is very popular in places like California and the Southwest. It has a high resistance to wind and fire, requires little maintenance and is easy to repair.
What Makes It A Green Product
- Made from abundantly available, inert material.
- Should contain a minimum of 5% post consumer recycled content or 20% pre consumer recycled content.
- Extremely long lasting, up to 100 years.
- The corrugated design has a cooling effect on the roofing system since air is able to flow around it.
Negative Environmental Considerations
- This is a heavy material so proper roof support is an issue.
- Binding clay tile requires high firing temperature in excess of 1100C, the higher the temperature the longer the life of the tile. The high temperatures involved lead to a high embodied energy and life cycle cost.
- Hail can shatter clay tile, so it is not the best option for climates with extreme weather.
These composites are made from wood fiber, fine aggregate and cement. It can be colored and shaped to look like slate, wood or tile.
What Makes It A Green Product
- Fiber-cement is resistant to moisture, rot, buckling, fire, termites, salt spray and most harsh weather conditions.
- It is lightweight and typically carries a 50-year warranty.
- Should be manufactured with recycled cement or recycled waste products such as fly-ash.
Negative Environmental Considerations
- There are various pollution problems associated with manufacturing cement due to the use of Portland cement. To reduce pollution, substitute alternatives such as fly ash and slag for Portland cement.
- If moisture gets into fiber-cement shingles, the fibers will absorb the moisture. If the wet fibers freeze, they can expand and damage the shingle. Therefore fiber cement composite slates and shakes are not recommended in northern regions or at high altitudes.
- Fiber-cement shingles can be easily damaged by hail.
- Care must be taken when cutting fiber cement to avoid inhaling potentially dangerous particles.
Green (Vegetated) Roofing
CSI Division: 073363 | Residential Category: Vegetated Roofing
These roofs are planted with vegetation. Also known as "living roofs", they are protected-membrane roofs with soil and plantings (as well as insulation) installed above the membrane.
What Makes It A Green Product
- Detain over half the rainwater from a typical storm, reducing often-high loads placed on sewer systems after rainfall.
- Act as an additional insulating layer to reduce unwanted summer heat gain and winter heat loss.
- Can be a wonderful architectural element that absorbs carbon dioxide and helps reduce building heat gain and urban heat islands.
Negative Environmental Considerations
- Since these are multilayered roofing systems, they can be thicker and heavier than conventional roofs. Therefore, the roof structure needs to be engineered to accommodate any increased weight on the roof.
- Green roofs must also be watered, which can be expensive, however, use of native plantings and rainwater harvesting will significantly decrease, if not eliminate, the amount of water needed for landscaping.
EPDM (ethylene propylene diene monomer) rubber is one of the most common types of low-slope roofing material in the US.
What Makes It A Green Product
- EPDM is easily reusable if it is loose or has been machanically fixed or ballasted.
- Is a lightweight material that can have a class A fire rating, pass wind tests up to 110 mph, and be sawed and nailed like wood.
Negative Environmental Considerations
- Recycling is possible, however, the process requires a lot of energy and may result in a lower grade recycled product.
- Membranes have been known to shrink so careful perimeter detailing is required.
- EPDM is a petroleum-based product.
Slate Roofing
CSI Division: 073126 | Residential Category: Slate Shingles
Minimally processed cut or split rock. Natural slate formed within the Earth's crust many millions of years ago when mudstones were subjected to colossal heat and pressure, causing partial recrystalisation of the minerals during a process known as metamorphosis. These rocks are split along natural faults or cut to produce the roofing slate. It creates a distinctive look and has a good fire rating. If you don't have travel long distances to get it, slate can be an excellent green roofing option.
What Makes It A Green Product
- Slate is durable and doesn't require a lot of energy to manufacture, especially when salvaged slate is used.
- When properly installed, slate can last well over 100 years with only minor maintenance.
Negative Environmental Considerations
- Only comes from the mid-Atlantic and Northeastern states as well as from Europe; therefore depending on where you live, transportation costs and environmental consequences should be considered.
This product is often used in roofing applications and is a good choice for roofing provided it comes from certified, salvaged or recovered wood sources.
What Makes It A Green Product
- Wood should come from properly managed forests or be certified by a third-party organization. Certified wood is widely available.
- Recovered and Salvaged wood is widely available and should be used, provided all appropriate documentation is presented.
Negative Environmental Considerations
- Avoid wood products treated with preservatives, as these chemicals may leach out and pollute groundwater.
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