Innovation Challenge Spotlight: Siding & Roofing
The Innovation Challenge: Create a building product that is safe, healthy, affordable, effective, and designed to be returned safely to nature or industry after use. This blog, posted weekly leading up the announcement of the Innovation Challenge winners on November 15, spotlights the key issues with conventional building materials and how the ten finalists’ innovations stand out. This week, we focus on siding & roofing.
Conventional siding options are characterized by environmental trade-offs. Factors to consider include:
• Extraction of resources to produce the siding
• Pollution released during production
• Waste during installation and disposal
• Material inputs and embodied pollution needed to replace or maintain siding with poor durability.1
Here’s a quick look at the key issues with three popular choices:
Vinyl siding is one of the most popular options, but it is made from polyvinyl chloride (PVC), the manufacture of which produces toxic compounds including highly carcinogenic dioxin.2 Dioxin is also released if PVC burns, whether in house fires or landfill fires. It can travel far from PVC manufacturing facilities via atmospheric circulation, affecting people and wildlife across a wide geography.3
Wood siding is often made from large trees, which take a long time to regenerate.4 Look for Forest Stewardship Council-certified wood where possible.
Fiber-cement siding is very durable, but it has a high embodied energy because of the cement content.5
As with siding, durability is a key issue when comparing roofing options since roofs are subjected to intense weather wear and replacing one requires an additional roof’s worth of materials, energy, pollution, and waste. The overwhelming majority of roofs are made of asphalt shingles, which have warranties of 20-40 years, depending on the particular product. Clay, cement, fiber-cement, and metal roofing options are also available and are usually more durable, though less frequently used.6
In addition to durability, it’s important to consider waste when a building is remodeled or replaced. Nearly a third of the demolition waste from homes is asphalt shingles.7 The construction and demolition waste situation is actually pretty staggering; Americans landfill approximately 136 million tons every year.8 Choosing durable building materials that can be reused or recycled has great potential to change the game.
How the Finalists Stand Out
GR Green siding and roofing is made primarily from recycled milk bottles and grocery bags and surplus industrial limestone, all waste products. It is highly durable, demonstrated by a 50-year warranty. At the end of its life, it can be recycled into new siding and roofing. It is a high-performance product made from recycled and recyclable materials.
1 Wilson, A., & Malin, N. (1997). Residential Siding Options, Environmental Building News, 6(7). Retrieved from http://www.buildinggreen.com/auth/article.cfm/1997/7/1/Residential-Siding-Options/
2 Wilson, A., & Malin, N.
3 Healthy Building Network. (2012). PVC Plastic. Retrieved from http://www.healthybuilding.net/pvc/facts.html
4 Wilson, A., & Malin, N.
5 American Institute of Architects. (Date Unknown). Considerations in Selecting Siding Materials. Retrieved from http://www.aiacbcgreen.org/siding.php
6 Malin, N. (1995). Roofing Materials: A Look at the Options for Pitched Roofs. Retrieved from www.buildinggreen.com/auth/article.cfm/1995/7/1/Roofing-Materials-A-Look-at-the-Options-for-Pitched-Roofs/
7 Construction and Demolition Waste Quantity and Composition. Retrieved from http://www.istc.illinois.edu/tech/cd-waste-composition.pdf
8 Construction and Demolition Waste Quantity and Composition.