There are two main roofing materials that are used by chemically sensitive folks or those avoiding toxins – asphalt shingles or standing seam metal roofs.
The most extremely sensitive will go with metal.
We also need to consider the underlayment and sealants used.
Some of the traditional sealants can be toxic and potent so be sure to carefully select all components in the design stage.
This article was written with the assistance of Andy Pace, a Healthy Home Concierge with over 30 years of experience in the healthy home building materials industry.
This article contains affiliate links, upon purchase I earn a commission at no extra cost to you.
1. Roofing Materials
Asphalt Shingles
Asphalt shingles are by far the most popular roofing material in the US and Canada.
Even most chemically sensitive people go with this choice in the end (though likely not the most extremely sensitive).
They are made from asphalt reinforced by fiberglass wood or cellulose, and mineral granules.
The first line of shingles has extra asphalt on the back.
They can contain PFAS.
This is the lowest-cost roofing material and virtually every roofing company is familiar with installing these singles.
The cons are that they are not the most durable or long-lasting option.
And for sensitive folks, there is some asphalt odor here, but it’s not as bad as liquid asphalt that you may have seen used on some roofs or in the redoing of an asphalt road.
Be sure to get samples and test them out for yourself.
Composite Shingles
Composite shingles are another possibility.
Though not all brands have proven themselves over time.
Class-action lawsuits have been initiated against “lifetime” roofing products with names like Hardishake, Maxishake, and Permatek which have prematurely failed. Certainteed also got rid of their Symphony polypropylene slate-look shingles.
More info and brands can be found in my book and course.
Standing Seam Metal Roofing
The main alternative to asphalt shingles, especially amongst the chemically sensitive, is standing seam metal roofs.
The roofing panels meet in raised seams that interlock to keep moisture out.
Metal roofs are also good against heavy snowfall or wildfires.
Metal roofs last a long time, though they are more expensive than asphalt.
Installation requires special skills and not every roofing company knows how to install a standing seam metal roof (though this is much more common than composite shingles).
The most extremely sensitive may want to learn about different paints used on the metals to select the best one for them.
Decking
Decking/sheathing options are covered here.
The most common option for the chemically sensitive will be plywood, but there are other options to consider.
Underlayments
Under an asphalt shingle roof, an asphalt felt paper underlayment is used.
This does not add significantly more off-gassing.
Under a metal roof you can use a plastic underlayment, the ones I have checked out have almost no odor.
Synthetic roofing underlayments look, feel, and smell similar to house wrap.
Synthetic underlayments come in permeable and non-permeable options.
Be sure to consult with your architect or building science expert on which one is suitable for your roof design.
These two kinds of basic underlayment do not replace peel-and-stick ice dam underlayments.
Ice dam underlayments are peel-and-stick, thicker, and impermeable.
They help prevent ice dams and water damage to your roof in certain climates.
They are used under both metal and asphalt roofs.
Synthetic underlayment is the basic underlayment that is used across the whole roof over the decking.
Brand examples can be found in my book and course on building a non-toxic home!
Baffles
Baffles are made out of foam or plastic – SmartBaffle is nontoxic polyethylene.
Roof Sealants
Tape/Putty
Butyl tape is used on metal seams. This is actually a putty that comes in a tape roll, it is very benign and will work for almost all chemically sensitive folks.
Caulking Sealants
Asphalt caulking and sealants are super strong in odor and offgassing.
They are used to seal nail holes around metal flashing and shingles in new roofs, and as the traditional flashing around chimneys, etc.
Sensitive folks should avoid liquid asphalt sealants and urethane ones as well (most urethane caulks as well as liquid urethane sealants).
I would not use a butyl caulking either.
The best types for the chemically sensitive can be found in my book and course.
Avoiding Liquid Asphalt
There are other flashing types, and other roof designs that can help you avoid liquid asphalt which are mentioned in the book and course.
Cleaning
You can hose off a metal roof with a hose and dish soap
Corinne Segura is an InterNACHI-certified Healthy Homes Inspector with certifications in Building Biology, Healthier Materials and Sustainable Buildings, and more. She has 10 years of experience helping others create healthy homes. You can book a consult here.
Join the top Substack on healing from MCS and mold!
Sarah
After new roof install, I’m reading about the importance of ventilation which I understand, at least in theory. Here’s my question: If the odors inside my home are manageable, why would I open windows the first fews days after install that will also bring more odor into the house? If the odor isn’t overpowering, maybe it makes more sense to keep things closed and to run my air purifiers w/heavy duty carbon filters for the first few days. It seems like opening windows risks pulling more smelly air through the house from the new roof. Yes, I would be having an intake and exhaust system set up with fans, but I’d still be pulling smelly air into the house with the intake. Not sure the best course of action. Any ideas would be most welcome.
Janet Olivier
Hi Corinne.
I would like to ask if regular treated wooden roof batterns are likely off gas chemical odours that will seep into the attic conversion room ? As the excisting ones have rotted and a cause of mycotoxic illness for my son and self and are being removed . The new wooden batterns have been delivered and stored outside affect our MCS severly .
I would be very greatful of your advice as also we have no where safe during the reconstructon process .
Thank you for considering the above.
Sincerely
Janet
Corinne Segura, Building Biologist
in the UK? I’m not sure what they are treated with there, I think there are various options but I could be wrong
Clara
What material would you recommend for a flat roof? (Rainny/cold climate). Our builder only does plywood deck, 120mm kingspan roof insulation boards with a trocal membrane finish. According to Google this means PVC. How toxic can this be? Can this leach chemicals to the indoor air and put our family at risk or should it be ok because the roof will be outside? We will be out of the house during the installation. Please help, we have a baby and I am very worried. My partner is really pushing for this. Thank you
Corinne Segura, Building Biologist
see if they can do TPO and look carefully at the glues
Sarah
Timing strategy question: Do you think it makes most sense to do the roof replacement in fall so it can slowly off-gass w/o the intensity of summer sun and heat, or better to just get it overwith and do it spring while heading into warmer weather?
Corinne Segura, Building Biologist
im not totally sure! it would be hard to survey that as we would need people that have done both but i would go for a time that at least had one week of hot weather before going colder or less sunny
Sarah
Thank you for this and your other replies. I’m finding that the roofers I’m vetting are pretty rigid in the products they use and I get it. They want to be able to stand behind the work w/their warranty and to use something different throws a wrench into that. The only option I’ve been given so far is to use synthetic underlayment instead of the more traditional underlayment. What I was told was that they want the roof to breate as much as possible so wouldn’t install synthetic underlayment in all situations, but since we have soffits all around and a good ridge vent (with the plan to install an even better one when the roof is replaced) they would be fine going w/the less breathable synthetic. But I’m inclined to go w/what you shared regarding the caulks and sealants being big offenders. Feeling super nervous about having a new roof, how long my house will stink, and how sick I may feel.
Corinne Segura, Building Biologist
synthetic comes in permeable and non-permeable, the builders/contractors cannot and should not be making those building science decisions. They are more often wrong about that kind of decision. Though if almost all houses in your area use tar paper and you choose a synthetic with that same permeance that is likely a safe bet.
Sarah
So grateful for the info on this page about roofing materials. The roofers we’ve talked with thus far have said synthetic underlayment smells much less than traditional felt/asphalt and would be willing to use it for our roof. After reading about permeable vs non-permeable will get back with them to explore those options. Can you explain what you mean by contractors not making these kinds of decisions? Are you referring to general contractors or roofing contractors? I presume the former, but if the latter, not sure I understand.
Corinne Segura, Building Biologist
Both general contractors and roofing contractors are not trained in building science. Unless this is a special interest that they personally have and they’ve done courses in this and researched it, they cannot make building science decisions like the permeability of the roof underlayment. Of course, following the standards that are usually used in your area by almost everyone is likely to be fine. But the more you get into unusual choices, the more important it would be to have somebody look at that and make sure that it’s being done right.
Sarah
Just clicked into the link for your book, but it looks like it’s only available on kindle, which I don’t have. Are there hard copies?
Corinne Segura, Building Biologist
only kindle but you dont need a kindle device or even the app
Sarah
I need to replace my asphalt single roof w/another of the same kind (strict HOA) and am dreading the off-gassing from various materials. I don’t think I’m going to have much control over material options because reputatable roofers have a whole system they use (some of which is dictated by the manufacturer, are warranty related, etc.) I’m extremely sensitive and can smell in my home when contractors use caulk on the exterior if it’s particularly noxious (which, mercifully, all of them aren’t). Any ideas about how long a new roof of this sort can transmit odor into one’s home? I realize this question may be hard to answer because there are so many variables, none the least of which being how everyone is different, but if you have any perspective, I’m all ears!
Corinne Segura, Building Biologist
the caulking and liquid flashing is where you have the most control and can make the biggest impact
Sarah
We found one very reputable roofer who seems willing to researching caulk alternatives. Not sure what liquid flashing is? Is that some kind of goop that is part of flashing install?
Sharon
I planning buying your book, but for right now I just have a question about the Iceand Water Shield. You didn’t say if it was safe for peoplewith EI in the valleys and drip edge
Corinne Segura, Building Biologist
the normal ones are asphalt, a better alternative is in the book
Pauline R.
We just had a new roof put on and I’ve been sick since ( 4 days ago) Lightheaded, weak, nausiated, headache, anxiety ) I also have a weak immune system. Does not bother my husband at all. I can smell it when I come back inside, after being out for an hour or so. My symptoms also clear a little when I’m out of the house. Trying to figure, pinpoint what it is. Been discussing these with the roof contractor. The smell is like a piece of Particle or plywood he had left over, called Waferboard. Ordor was stronger in the attic area. I’m so confused and beside myself.
Pauline R.
I’m wondering if it is the Waferboard or synthetic felt ABC. SHingles are from Tamko.
Corinne Segura, Building Biologist
OSB, glues, asphalt shingles, caulking and liquid flashing all off-gas
Rita
Great article!
I wondered if you have found the ice and water shield to be an issue for chemical sensitivity? I have seen some postings on the internet that is out-gasses on hot days and causes smells in interiors long after installation.
I’m getting a roof replacement and concerned about it.
Corinne Segura, Building Biologist
It could be yes if you are severe. Test out different brands.
Harriet
My roofer wants to use a sealant made by Karnak on my lifting shingles. I’m extremely chemically sensitive and my house isn’t insulated. I’m concern the low VOC PRODUCT will smell and make me sick. He won’t give me other options.
I’m open to suggestions.
Thank you
Corinne Segura, Building Biologist
I’m not familiar with it, you would want to see what type of sealant it is and get a sample to see how you do with it
Harriet
Thank you. Do you have recommendations for odorless, non-toxic sealant so I can inquire to the manufacturer.
Vicky L Hughes
Green sells some that are not toxic
Peter Koeppel
I’m having my roof replaced with a metal roof. The installer wants to use a product called FillPro Soft Type Backer Rod Made Armacell. It’s made of a pliable Bi-cellular polyethylene foam material. The spec sheet says its non-gassing and chemically inert. It’s made in Canada. If you click on this link it will take you to the product page and then click on technical datasheet to see the product specs: https://www.armacell.com/en-US/fillpro-soft-type-backer-rod Let me know if you think this product is safe for a chemically sensitive person.
Corinne Segura, Building Biologist
backer rod is safe
US Roofer
Thank you for this information. I have a metal roof on my house and for its maintenance and repairing, I am currently using Liquid butyl rubber that resolves all kinds of roofing issues with just its primer free, single coating. EPDM liquid butyl rubber gives the best waterproofing solution for metal roofing making it more durable and long lasting for a fraction of cost of a new roof. I also highly recommend this amazing sealant to every house owner. Its durability and resistance to weathering makes it an excellent choice for roofs that are exposed to harsh weather conditions. It also given me further premium protection from all kinds of external harmful elements.
Corinne Segura, Building Biologist
I wouldnt recommend that for most sensitive folks
Greg Sherbert
Are you concerned about PFAS in metal roof coatings?
We are replacing our old asphalt shingle roof with standing seam metal. We plan to capture the rainwater for use on our farm for garden and livestock watering. The metal either comes as bare Galvalume or Galvalume with a baked on Kynar finish (PVDF). Prescriptions for a Healthy House doesn’t seem to have any concerns about this coating being made with PFAS, and neither do I for the first 20 years. But after this roof coating sits in the sun for a few decades and begins to fade and eventually chalk won’t I be adding PFAS chemicals to my rainwater tank and then distributing them around my landscape (and into my family when we consume food watered with this water)? I recognize there are potential health issues with galvanized/galvalumed roofing too, I’m just trying not to create a problem that I will regret later.
Would you use plain Galvalume or the PVDF finish roofing for capturing rainwater?
Corinne Segura, Building Biologist
it’s debatable whether it’s a PFAS, depends on what definition used. Also this says plastic PVDF doesn’t leach into water https://www.aquatechtrade.com/news/desalination/viewpoint-graeme-pearce-reach-on-membranes
It lasts more than 20 years. But as for the future breakdown I’d be most worried about it’s eventual disposal
Greg Sherbert
So would you go with a PVDF coated roof instead of bare Galvalume if you were harvesting the water for garden and livestock use? Or is there another option you would prefer?
Sara
Hello,
How do rubber roofs usually impact people with chemical sensitivities? I am the canary in our family (sensitive to everything) and we are looking at possibly buying a house with a rubber roof. The rubber roof was installed in 2023. It’s a pretty flat roof so I’m not sure that a metal roof is even an option. Would it be done gassing off? Or is it the type of thing that would continue to gas off any time it’s a hot sunny day and the sun heats it up..? Thanks for any input you can share!
Corinne Segura, Building Biologist
TPO is pretty benign, should be ok for most sensitive folks. The glues are probably not OK but since it’s been a while it might be just fine. I haven’t tested the conventional glues for that but even really toxic glues can offgas fast.
Carla MI Henderson
Corinne,
I am not chemically sensitive, but I’m building “Healthy home” using most;y healthy materials 0-very low VOC. In this case, how comfortable would you be using a certainteed asphalt roof if I adhere to your suggestions on using cleaner underlayment and sealants? Should I consider other roof types like Ecostar’s composite roof? It’s a 4400 square foot house so a metal or wood roof would be very expensive.
Thanks,
Carla
Corinne Segura, Building Biologist
asphalt shingles are fine in this case
Alara
You didn’t cover the type of roof often in Az. It’s the pretty clay thingy kind. Looks like curved clay . Hope u know what I mean:)
Personally, even though I watch what I use/ if poss/ I don’t see how what’s way up on the roof would be as much concern as what’s in the home proper. Just my opinion. Thanks.
Corinne Segura, Building Biologist
I’m only covering the two most common roofing materials here. This does affect people who are the most extremely sensitive and sometimes, or some pages on my website, won’t make sense to people are not not chemically sensitive.