Roofing Materials Ranked by Environmental Impact
stephanieherynk
| Posted in General Questions on
Hello and thank you for your input!
We’ve had several clients ask about the environmental impact of various roofing materials, and I’m having trouble finding a reliable source of information as to which of the following are the most/least environmentally friending roofing materials. A lot of the articles are written by roofing material manufacturers, thus carry a huge bias.
Has someone written an article ranking them?
How would you rank them and why?
– Metal
– Composite
– Cedar Shake
– Slate
– Clay
– EPDM
– others?
Thanks again 🙂
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Replies
The BEAM tool has most of those options: https://www.buildersforclimateaction.org/beam-estimator.html
Thank you Michael.
The problem I see with this kind of ranking is there's no one thing that is "environmental impact." Is it worse to foul the air, earth or water? Is a product that has a lower lifetime carbon footprint better, even if its manufacture leads to the destruction of environment?
These are not easy questions to answer.
That's exactly what I'm struggling to communicate... I was hoping someone had made a list that factored in the averages of those concerns to come up with a "least damaging" option. Each material has their pros/cons and rank differently based on each client's priorities.
In that case it's very subjective; every situation is different and everyone has different priorities. My list would look like this:
Asphalt: most affordable, relatively easy to find installers, can be recycled at the end of its life, leaves money for other things.
Metal (steel): can be standing seam, snap-lock, or exposed-fastener. Or specialty installations such as flat-seam copper. Relatively popular in my area but still expensive. High embodied carbon but relatively long life to offset it. Can be easily recycled at end-of-life but the BEAM tool does not account for that.
EPDM: when I am forced to do a low-slope roof, it's the only reasonable option in my area. Relatively short life, hard to find installers though it's easy to do. It seems like it could be recycled but I don't know of any recyclers.
Cedar shake (hand-split) or shingle (sawn): comes from a theoretically renewable resource but typically from old-growth trees that would take centuries to regrow. Very short lifespan, high labor costs, should be treated for fire resistance which makes the end-of-life product toxic waste.
I don't use clay or other materials for roofing.
Thanks Michael!
Is pvc not common where you are?
I have never seen PVC on a roof in Maine. I'm sure someone has done it but EPDM is the standard for low slopes here.
I didn't include PVC on the list at all due to its high environmental impact. They do use it here in the PNW though yes.
I had no idea cedar shakes were old growth, there are 2 cedar mills here in Maine that churn out shakes all season. I just assumed they were renewable like pine.
tim_williams,
That's the big dilemma I've found with all cedar products. New growth cedar simply doesn't last.
Tim, I would not use the white cedar we have here in Maine on roofs. I have used red cedar shingles on roofs on Nantucket, and would consider Alaskan Yellow Cedar, both of which are significantly more rot-resistant than white cedar but (untreated) only last 10-15 years on a roof.
White cedar grows slowly; it's renewable but not a rapidly renewable resource.
Thanks for the responses, I was thinking of cedar for wall cladding, but the issue still applies.
Michael,
My white cedar roof shingles (#2, with knots) lasted 22 years without any leaks. The pitch is 12:12, which helps.
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Every single "product" on earth has the residue of the manufacturing process attached to it, whether cutting down trees, smelting metal, pumping oil, mining minerals, etc, as well as the costs for transportation and installation.
I would think the primary consideration for choosing materials is "How long will it last and what do you do with it when its life cycle is finished and you have to replace it"? All things considered, I would choose metal first. With proper maintenance and installation a metal roof can last you 100 years and at the end of its life it can be completely recycled. Of course, you must specify the longest lasting underlayment as well.
As a second choice, it would either be slate or clay, but they are both much heavier than metal and would necessitate building a much more robust building frame in order to support the weight.
I have been thinking about this and have come to similar conclusion.
A building material that has residual value is the greenest option. Anything that goes to the dump but can degrade is next (ie wood). Around me anything but metal goes to the dump, so asphalt shingles would be on the bottom of the list.
"A building material that has residual value is the greenest option." That's a great way of putting it, thank you. How do you advise your clients who can't afford a metal roof? I haven't seen too many new cedar shake roofs here in Portland. I suppose they land on the longest lasting composite shingle they can afford?
Part of the equation is "how long does it need to last?"
Hi Rockies. Considering the climate crisis I've been trying to prioritize carbon in my decision making. The BEAM tool was helpful regarding comparing the relative impacts. I was surprised to learn that asphalt roofing had a far smaller carbon cost than metal roofing. I agree there are other considerations and I used to think longevity was a top priority but have been rethinking priorities lately.
Metal is at the top of my list as well. Slate or clay I really don't know much about their manufacturing processes/impact/lifecycle. I'll do some more research but if anyone has any insight, I'm all ears.
I find that most people on this planet don't understand carbon - production, utilization, storage, etc. I certainly don't. Tell people that "You should reduce your carbon footprint" and they'll give you a blank stare.
As to the BEAM tool telling you that asphalt shingles have a far smaller carbon cost than metal roofing, ok, but how often will you replace the asphalt shingles compared to the metal roofing? Twice as often in 50 years? Three times? But the old shingles get "recycled" - how and where?
If asphalt shingles have the look you prefer and they are in your budget (and metal roofing is not), then go for asphalt. Based purely on longevity, I would choose metal.
Good point in asking how/where asphalt shingles get recycled. When I replaced my lower ~5 square roof this summer I couldn't find anywhere local that regularly accepted asphalt shingles for recycling.
There is at least one company prototyping asphalt shingles made from other recycled asphalt shingles, but yes until the day comes when the closed system is achieved I don't see it as sustainable as metal due to longevity.
I've been hoping to see more comments regarding euroshield rubber shingles. They're made mostly from recycled truck tires in Canada and the samples I've received feel very durable. I've been keeping them outside along with other samples to help decide what material to use on my upper roof this year.
I wish euroshield's fire rating was better and that the price was closer to that of asphalt shingles. Their material price is $500-700 per square vs $100-150 for asphalt (plus underlayment and such). Davinci synthetic slate and tile is beautiful but even more expensive.
acrobaticnurse_Eli,
I pay $370 CDN a square for metal snap-lock panels.
Does this take into account trim? I’ve found that including that generally brings it into the $500 sq territory.
freyr-design,
No, and it is for a galvalum finish.
But what continues to surprise me is the installed cost of metal roofs being so high compared to other types, when their materials aren't proportionally more expensive, and metal roofs are fairly easy to install.
What company do you prefer for metal roofing? I will be replacing a simple ~12 square gable roof in North Carolina.
-Eli
Eli,
Westform Metals in Coastal BC, so it probably isn't useful to you.
I am not familiar with rubber shingles. Interesting. Davinci synthetic slate appears to be made of resins which to me ranks low on the list again in terms of environmental impact.
Acrobatic: I would have a look at the Metal Roofing Learning Channel on Youtube.
https://www.youtube.com/@WesternStatesMetalRoofing
It is sponsored by Western States Metal Roofing but they have a ton of useful information on roofing types, pros and cons, and installation methods.
https://www.youtube.com/@WesternStatesMetalRoofing/videos
As to the fire resistance of rubber roofs, do they calculate the level of resistance to fire based on ember contact, direct flame contact or radiant heat levels? In the case of direct flame contact and prolonged high temperature radiant heat I would be concerned with the shingles melting in addition to them actually catching on fire. And if they do catch on fire, can they self-extinguish once the flame front has passed or will they transmit heat through to the roof sheathing and set that on fire?