In 2005, Missouri turned old roofing shingles into part of Route 61/67; six years later, MoDOT still called the St. Louis County pavement's performance favorable

Every year, 11 million tons of old asphalt shingles are ripped off American rooftops. Almost all of them would have been tossed into the landfill. The Environmental Protection Agency has put the figure at more than 11 million tons of waste shingles generated annually in the United States. The road beneath your feet could have been made from these shingles, keeping your living room dry from the rain.

A 2015 case study titled “Missouri DOT Pioneers Roofs to Roads Efforts, Inspires other DOTs to Follow Suit,” published by the AASHTO Center for Environmental Excellence, found that Missouri’s Department of Transportation has been crushing old roofing shingles and using them within the asphalt mixes used to resurface their roads. They have been doing this since 2003 under an initiative called “Roofs to Roads.” It is one of the most unglamorous, yet effective, climate-friendly projects in the country and often goes unnoticed.

How a roofing problem turned into a paving solution


A local contractor suggested to Missouri DOT in 2003 that they could try reusing the torn-off roofing shingles within their asphalt mixes. Since they are made with asphalt binder, it made sense to reuse them. They did some lab tests and ran a trial scheme in 2004. By 2005, they had a trial section of road on Route 61/67 in St. Louis County. As of six years later (2011), MoDOT reported the section was still performing well, with some slight reflective cracking. A similar scheme was carried out near Joplin, and they saw similar results. In 2006, they had a temporary specification to allow them to use the recycled shingles.

What the numbers show

Per Missouri’s reported figures (covering 2004–2014), the use of recycled shingles saved the state $3 to $5 per ton of asphalt mix. Taking a 30,000-ton resurfacing job as an average example, this works out to savings of $90,000 to $150,000 per project. That saved money can then go toward fixing the next stretch of road with potholes. Between 2004 and 2014, Missouri kept nearly 395,000 tons of shingles out of landfills.

This isn’t only good for the environment, states are also facing financial pressure, and landfill space is limited. Using recycled materials helps reduce costs and is also a win for the environment. Around 20 state DOTs have implemented or are exploring post-consumer recycled shingle programs. That said, adoption is uneven: some states, like Texas, have trialled the concept since 1990, while large areas of the country, including much of the West, use little to none.

Does the science actually hold up?

It is fair to be sceptical about recycled infrastructure. We wouldn’t want to use a quick fix that would fall apart after 5 winters. However, Missouri worked with several other states to carry out research. They ran a Transportation Pooled Fund Study TPF-5(213), on the “Performance of Recycled Asphalt Shingles in Hot Mix Asphalt,” conducted at Iowa State University’s Institute for Transportation with the help of the Federal Highway Administration and transportation departments of California, Colorado, Illinois, Indiana, Iowa, Minnesota and Wisconsin.

The results showed no rutting, thermal cracking, or fatigue cracking after 2 years of monitoring. They did, however, see reflective cracking, which is cracking from the layer below, on 5 of the projects. The issue with these shingles is that they are not perfect. The quality will affect how well they work. This includes the size of the shingle grind and binder content.

Why you should care

This is a rare case of climate-friendly infrastructure that isn’t being sold to anyone. There’s no influencer campaign behind it, just transportation engineers who found a cheaper, practical alternative to new asphalt binder by reusing roofing waste that would otherwise go to landfill. The next time you drive on freshly laid blacktop, there’s a decent chance part of it used to be a roof.