Via Community News Service, a University of Vermont journalism internship
TOWNS STATEWIDE – With the push to reduce landfill waste and embrace green construction in Vermont, one of the most sustainable materials out there is a tried-and-true option: slate roofing.
“It’s not good because it’s old — it’s old because it’s good,” said Caitlin Corkins, architectural historian with the Vermont Division for Historic Preservation.
Vermont slate, which can be found adorning homes all over Burlington, lasts 125 years or more if maintained properly, according to the Burlington Design Guide.
“The beauty of it is they are so resilient,” said Jeff Spencer, owner and operator of Stewardship Slate LLC, a local roofing firm.
Slate is fire and water-resistant, with the piece-by-piece nature of it offering unique breathability.
“You can kinda take parts of it that are falling apart and then put it back together again … can’t really do that with other types of roof,” Spencer said.
Slate is among the most sustainable construction materials in common use, especially compared to the most common roofing alternative: asphalt. Slate requires relatively little processing, coming almost straight from massive land deposits in places like Fair Haven in the southern Champlain Valley.
Before being usable for roofing, slate must simply be split and hewed into shape, giving it a very low embodied energy — the total energy consumed to produce it.
Asphalt, on the other hand, is neither durable nor environmentally friendly. Asphalt shingles, featured on over 75 percent of roofs in the United States, have a service life of only around 15-25 years, according to the Burlington Department of Planning and Zoning (DPZ). Made from petroleum products and fiberglass, asphalt shingles are typically not recyclable.
“In the past they have been known to sometimes contain asbestos and PCBs, although that is rare now as many of those additives have been phased out,” said Josh Kelly, solid waste program manager at the Vermont Agency of Natural Resources.
However, Kelly added: “Asphalt shingles are known to contain PFAS, an emerging set of chemicals of concern.”
PFAS have come under the attention of ecologists in recent years due to their environmental persistence and ties to a spread of health issues, according to the U.S. Environmental Protection Agency.
Because of its relatively short life span and non-reusability, old asphalt roofing generates tons of landfill waste. Construction and demolition (C&D) waste as a whole represents 23.7 percent of all solid waste in Vermont, according to the 2023 Vermont Waste Composition Study. Asphalt shingles grew in their proportion of C&D waste from 18 to 25 percent between 2018 and 2023.
Corkins sees slate as a means to combat this trend.
“Thinking about the long-term impacts to the planet, in using materials that nature produces and last a long time … it’s not just good preservation, it’s good environmental consciousness,” Corkins said. However, “at the state level we don’t have … blanket authority to review projects.”
That typically comes down to individual municipalities, with local governments across the state each having their own rules related to roofing.
Burlington mandates that property owners obtain a report assessing the quality, repairability and maintenance cost of a slate roof to replace it with another material.
But this only applies to buildings listed on the National Register of Historic Places, the administration of which is a function of the Vermont Division for Historic Preservation, according to Corkins.
“When a project is going to happen … one of the first things we look at is, is this building historic and if it has already been identified and listed,” she said.
In reference to his current roofing project in Burlington, Spencer described this process: “This is actually a little more expensive than what they were gonna pay to have the asphalt done, but the city looked at those two prices and … they couldn’t justify removing the slate.”
The upfront cost of installing entirely new slate roofing is almost double that of asphalt on average, per the DPZ roofing guide.
While this can be daunting, slate’s longevity may make it more cost-effective over the long term, and damaged slates can usually be replaced individually.
With the prevalence of slate roofing in Burlington’s historic neighborhoods, there’s a strong demand for contractors who specialize in slate.
“I started doing slate and I just kept getting more and more calls for it because there’s so few of us that do it,” said Spencer, one of only six contractors listed on the Burlington DPZ website. “It really is kind of impossible to keep up with demand.”
Contractors aren’t the only ones noticing this issue.
“When it comes to historic preservation and sort of more traditional building techniques, we have for a long time seen that there is more demand for that kind of skills than people that are doing the work,” echoes Corkins. “It’s something we talk about all the time.”
For more information or ways to get involved with historic preservation in Vermont, visit the Preservation Trust of Vermont website at https://ptvermont.org/.