Roofing: MATERIALS ENCYcLOPEDIA
Applications for this system
There are many different composite shingle products available, each using different materials. They typically use the following types of ingredients:
Recycled plastic or rubber
Wooden strapping or solid decking
Waterproof membrane or underlayment may be required
Ratings Chart for composite shingle roofing
The ratings chart shows comparative performance in each criteria category. Click on the tabs below for detailed analysis of each criteria.
- HOW THE SYSTEM WORKS
- ENVIRONMENTAL IMPACTS
- EMBODIED CARBON
- ENERGY EFFICIENCY
- MATERIAL COSTS
- LABOUR INPUT
- SKILL LEVEL REQUIRED
- SOURCING & AVAILABILITY
- CODE COMPLIANCE
- RAINWATER COLLECTION CAPABILITIES
- FUTURE DEVELOPMENT
Composite shingle System
While each proprietary composite shingle product is different from its competitors, they all share a fairly similar approach. The shingles are made from a recycled plastic or rubber material reinforced with some kind of fiber. As with all shingle roofing, the individual shingles are nailed to the roof surface side by side in consecutive courses, with a specified amount of reveal left on each course. The shingles are usually installed such that a section through any point on the roof would reveal three layers of shingle everywhere on the roof surface.
As proprietary products, each shingle will come with manufacturer’s instructions for installation. These instructions should be followed carefully, and should be examined in advance to understand all of the requirements of the roofing system.
Environmental Impact Rating
Harvesting — Low to High
Each composite shingle product has a different formulation with greatly varying quantities of recycled content. Post-consumer recycled content usually carries greater reductions in impact than post-industrial recycling. Determining overall quantity of recycled material is important, as many of the virgin materials in composite shingles are petrochemicals with all the associated extractive impacts, including greenhouse gases, air and water contamination and habitat destruction.
Fibers can come from low-impact or recycled sources, or may have moderate impacts in their growing and harvesting cycle, especially if they involve heavy pesticide and herbicide usage.
Manufacturing — Moderate to High
The use of recycled petrochemicals typically involves some degree of air and water pollution. Manufacturing processes can range from moderately to highly energy intensive. Research carefully regarding toxins or harmful by-products generated during manufacturing. If possible, try to find third-party verification of company claims.
Transportation — Low to High
Composite shingle production facilities tend to be small and regional. Transportation distances can vary from short and factory-direct to cross-continent and via many sub-distributors.
Installation — Low to Moderate
Most composite shingle products are installed with a minimum of power tools. Saw cuts can create toxic “sawdust” and release airborne toxins. Shingles cut with a sharp blade leave less waste on-site and in the air.
Waste: moderate to high
Composite products are often not recyclable because of the mix of ingredients used. Check to see if the product is accepted in local recycling streams or if the manufacturer accepts offcuts and leftover product for recycling at the factory. Otherwise, all offcuts will need to go to landfill. Quantities will vary from negligible to high, depending on the complexity of the roof.
Recyclable — Metal fasteners. Quantities will be negligible.
Landfill — Shingle offcuts, membrane or underlayment offcuts, caulking tubes. Quantities will vary from negligible to high, depending on the complexity of the roof.
Chart of Embodied energy & carbon
Energy Efficiency: n/a
Composite shingles can have an effect on energy efficiency depending on their color and density, with darker and heavier products having a greater negative impact on cooling requirements.
Material costs: moderate to high
This category covers a wide range of different products, with price points that span over the range of prices for other manufactured materials in this chapter. Quotations should be obtained for any composite shingle to compare individual brands directly with other options.
Labour Input: easy to moderate
Each product will have specific requirements that determine labor input, but in general the labor required will be similar to other shingle roofing systems.
Working at heights to install roofing has inherent dangers. Proper setup and safety precautions should always be taken when working on a roof.
Skill level required for homeowners
Decking — Easy
A homeowner with the ability to create a roof frame will be able to deck the roof for composite shingles.
Underlayment (if required) — Easy
Underlayment is lightweight and comes in rolls that are straightforward to apply.
Shingles — Easy to Moderate
As proprietary products, some shingle manufacturers may require that an approved installer is hired and may not sell directly to homeowners, while others may be willing to sell product directly to a homeowner for self-installation. If the product is available to homeowners, there is likely to be installation support in the form of written and/or video installation instructions aimed at first-time installers. The process is similar to that of any shingle-style roofing.
Caps and Flashing — Easy to Moderate
Composite shingle companies that support homeowner installation will have products and instructions to make cap and flashing installation as straightforward as possible.
Sourcing & availability: moderate
Most of the companies producing composite shingles are fairly small, and their distribution networks may be limited. Check for availability direct from the factory or for a local distributor in your area.
Most composite shingle manufacturers advertise lengthy warranties for their products, making this one of their main sales pitches. In theory, products made from recycled plastic or rubber should have a long lifespan. However, most of these products are less than a decade old so there is no historical data to back up these claims.
Most manufacturers will have data to show code compliance for their product. Check with the company to see what documentation they have available and get the building department’s opinion on the documentation before purchasing the product. If a company has met appropriate ASTM, CSA or other code-referenced standards, then the product is likely to be accepted. However, if there is only in-house data from the company, there may be hurdles to getting it accepted. Some companies will work directly with building departments to address concerns, which can alleviate some effort on the homeowner’s behalf.
RAINWATER COLLECTION CAPABILITIES: low to high
Earthbag foundations will have no direct impact on indoor air quality. A well-built foundation can help keep the floors and walls of the building dry and prevent other IAQ issues.
Resources for further research
Harrison, H. W. BRE Building Elements: Roofs and Roofing: Performance, Diagnosis, Maintenance, Repair and the Avoidance of Defects. London: Construction Research Communications, 2000. Print.
Composite shingles are likely to become a larger part of the roofing market, especially as asphalt shingles rise in price. As with any new product category, there will be a time during which numerous start-ups enter the market and offer a variety of options. Over the next decade, some of these will take hold and grow a wider acceptance and distribution network, while others are likely to fail and disappear. A decade will also give a better indication if the projected lifespan of the products is realistic or not. At this time, homeowners using composite shingles are taking the risks of early adopters. This can be a great opportunity to work with and support deserving companies as they establish excellent products in the marketplace, or it can be problematic if the product does not live up to expectations and the company doesn’t survive. Do your research well!
Tips for a successful composite shingle roof
1. As these products constitute a relatively new category of roof sheathing, it is wise to contact people who have had a particular product installed and get firsthand references.
2. Many companies offer training workshops or have online video training resources. Take advantage of any such offers to ensure correct installation.
3. Ascertain what kind of roof decking is required for a particular system, and whether or not any kind of roof membrane is required, as this will affect cost, installation time and environmental impacts.
4. If possible, decide to use a composite product at the design phase of the building, so that any particular details required by the roofing can be incorporated into the drawings.