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Least Toxic Window Frames – Aluminum, Wood, Fiberglass, or Vinyl?

Published: September 16, 2023 | Corinne Segura, Building Biologist

When choosing non-toxic window frame materials, windows made of thermally broken aluminum are the top choice, and that is the preferred choice of those highly chemically sensitive.

My second choice would be Accoya wood windows.

Some vinyl and fiberglass brands can certainly be considered, since they can be very low in off-gassing.

This article contains affiliate links, upon purchase I earn a commission at no extra cost to you.

Table of contents
  1. 1. Metal Window Frames
  2. 2. Wooden Windows
    1. Safer Wood
    2. Custom Wood
    3. Problems with Wooden Windows
    4. Chemical Wood Treatments
  3. 3. Fiberglass Window Frames
  4. 4. Vinyl Window Frames
  5. Window FAQs
    1. What are High-Quality Trusted Window Brands?
    2. Are Gas-filled Windows Non-Toxic? 
    3. Are Low-E Coatings Non-Toxic?
  6. Sealing Around Windows
    1. Caulking
    2. Sealing the Space in the Rough Opening
    3. Window Flashing
  7. Non-Toxic Window Film
  8. Non-Toxic Window Screens

1. Metal Window Frames

The bed in the loft of my tiny house with my aluminum framed window
Aluminum windows in my tiny house

Aluminum windows are the healthiest, safest option, especially for the chemically sensitive. It is what I used in my tiny house (pictured left).

On the interior, I added wood framing trim.

Thermally broken aluminum windows are all aluminum on the outside with a foam like polyurethane inside.

What is used in the windows as a thermal break is blocked by the glass and metal so there is no need to worry about off-gassing from that aspect.

Non-thermally broken aluminum windows are not a good idea to use as they conduct heat and cold and easily condensate.

Aluminum Clad

Aluminum-clad means there is an exterior of aluminum which usually has wood as the interior side framing.

Brands

Brands are mentioned in my book and course on healthy building.

Non-Aluminum Parts / and Paint

Non-aluminum parts and the different paint coatings on these windows are mentioned in the book and course.

2. Wooden Windows

a close up of a wooden window frame with a lever to open the top part

Wooden windows are usually treated with fungicides, pesticides, and insecticides.

You could use a sealer that seals in those chemicals like those mentioned in the book and course.

Standard wood is also prone to warping and water damage.

Safer Wood

Accoya wood used in some window brands uses a non-toxic process called acetylation to naturally provide rot resistance. 

They use no chemical fungicides or mildewcides and they claim this process helps to reduce shrinking and swelling compared to most solid wood windows. 

Custom Wood

You could go with totally custom-made wood windows, but they are more expensive and you still have to consider what kind of sealer you can tolerate on the inside and outside. 

For an exterior sealer, see my post on paints and sealers.

Problems with Wooden Windows

All wood (through and through) windows are not a good idea as they do not hold up well to moisture in the long run, Accoya wood claims to have solved this problem.

You can also consider ones that are wood on the inside and a more weather-resistant material on the outside (aluminum clad) if you like the look of wood inside. 

Consider also that the glue used in conventional wood windows could be irritating for the sensitive person.

Chemical Wood Treatments

Chemical treatments that I have seen on wooden windows are mentioned in the book and course.

3. Fiberglass Window Frames

the corner cut out of a fiberglass window frame where you can see the foam on the inside

Fiberglass and vinyl are other choices that will work for many people.

Some brands will cure quite quickly or be low enough emissions to not cause any issues.

There is one I sampled that I could not pick up any off-gassing from myself.

Some types and brands are better than others (in terms of off-gassing) and this could result in a preference of fiberglass over vinyl or vice versa.

Some chemically sensitive folks do perfectly well with these options.

Brands are in my book and course.

4. Vinyl Window Frames

the corner cut out of a vinyl window frame with plastic components on the inside with some grey foam

Vinyl is often not a healthy material, but since this is a hard unplasticized vinyl, it does not have very much of an odor or off-gassing.

I did not pick up any offgassing on the vinyl windows I tested and used in a little camping trailer.

I can pick up the off-gassing in some vinyl windows however, like those used in apartments under one year old.

uPVC indicates vinyl without plasticizers, which is the most harmful part of the vinyl for chemically sensitive folks.

Window FAQs

What are High-Quality Trusted Window Brands?

High-quality window companies recommended by architects are included in the book and course.

Are Gas-filled Windows Non-Toxic? 

Windows filled with argon or krypton gas have a higher insulative value, and both gases are considered non-toxic.

Are Low-E Coatings Non-Toxic?

The two main types of low-e coatings are both non-toxic. Either silver, tin oxide, indium tin oxide or titanium dioxide is applied to the glass in either a mechanically applied coating that is within a double pane window system, or it’s applied while the glass is still hot making it a more integral part of the glass.

Sealing Around Windows

Caulking

To install windows into the opening you can use caulking compounds that work for the chemically sensitive instead of the more standard types.

The best options for the chemically sensitive are in the book and course.

Sealing the Space in the Rough Opening

You can avoid spray foam here to seal the rough opening. It is not necessary, and using an alternative method, mentioned in the book and course, is not substandard.

Window Flashing

Peel and stick windows flashing – there are acrylic adhesive options now, some are 0-VOC.

Non-Toxic Window Film

Some of these films can work for most sensitive people.

Some are plastic that is bonded without an adhesive.

Those super sensitive to plastics will still have to be careful.

I mention a brand I like and tested out, including testing it applied to glass, in the book and course.

Non-Toxic Window Screens

Not all types are suitable here, some types off-gas and haven’t gone well for chemically sensitive folks.

Brands are in the book and course.

a banner that says new course on non toxic building materials on demand course by my chemical free house get it now with images of a computer with the course on the screen

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.

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Comments

  1. Laly

    December 20, 2025 at 3:38 pm

    hi Corrine! thanks for all that useful information! what about the windows in Nordic spruce kitset log cabins, they say is untreated spruce but use glues.
    thank you!

    Reply
    • Corinne Segura, Building Biologist

      December 20, 2025 at 10:16 pm

      ask what brand the windows are and then check if it’s really untreated

      Reply
  2. Kate

    September 5, 2025 at 10:38 pm

    When the standard very strong adhesive is used to fix architraves, such as no more nails or liquid nails. How long would you recommend leaving the property for during installation?

    Thank you so much for your tip in regards to the spray foam.

    Reply
  3. LEP

    January 30, 2025 at 5:31 pm

    Appreciate the content of this site. FYI, my exhaustive research recently led me to a great option for windows. Jeld-Wen has many models that are Greenguard Gold certified. The certificate can be found in the Documents/Sustainability section.

    Reply
    • Corinne Segura, Building Biologist

      January 30, 2025 at 5:55 pm

      thanks for sharing. I’m sure there are people who are interested in Greenguard Gold windows. However, I’m quite confident that all windows would meet GreenGuard Gold.

      Reply
      • LEP

        January 31, 2025 at 5:46 am

        You’re welcome. We like the fact that the company has gone through the extra expense and testing to certify their products. We find that certification as crucial to all products used on an upcoming new build.

        Reply
  4. Liz

    January 18, 2025 at 8:44 pm

    Do you know anything about Marvin Elevate Inspire vinyl windows? Our builder is planning to put those in but I can’t find any info on issues with off-gassing.

    Thanks!

    Reply
    • Corinne Segura, Building Biologist

      January 18, 2025 at 9:45 pm

      I talk about vinyl windows in general.

      Reply
  5. Mary Ann herryman

    October 23, 2024 at 9:33 am

    Thank you.. great info. Wondering if I need to worry about the wind blowing toxic anything from fiberglass or vinyl windows into my bedroom. Fumes or particles?????

    Reply
    • Corinne Segura, Building Biologist

      October 23, 2024 at 11:39 am

      It would not be blowing in particulates. As for offgassing I talk about that in the article.

      Reply
  6. DKI

    September 16, 2024 at 5:25 pm

    Thank you for this amazing resource! We have to replace the windows in my mother’s house and I didn’t even know where to begin, now at least I can look into your suggestions and ask contractors about those. Thanks a ton!

    Reply
    • Corinne Segura, Building Biologist

      September 16, 2024 at 8:09 pm

      you’re welcome!

      Reply
  7. Steve

    August 24, 2024 at 4:38 pm

    Hi Corinne, your website is AMAZING! Thank you! I am replacing my windows and looking at Pella wood aluminum clad vs Pella Fiberglass (Impervia). I just wanted to confirm: even though the wood has pesticides, fungicides, and insecticides (Pella brands theirs as EnduraGuard), you are saying that these wood windows are still less toxic than fiberglass windows. Is that correct? Thanks!

    Reply
    • Corinne Segura, Building Biologist

      August 24, 2024 at 6:37 pm

      Comparing which is less toxic is not really possible in an objective way. There are some fiberglass and vinyl windows that seem to have no offgassing based on perceptions by chemically sensitive people. With the wood you can also seal in those pesticides which will help though some people are very sensitive to those chemicals, they are overall minor. I would say my opinion would be that certain brands of fiberglass and vinyl could be better than the woods treated with pesticides. But options like Acoya wood are top of the line in terms of the best options out there for toxicity.

      Reply
      • Steve

        August 25, 2024 at 7:22 pm

        Thank you, Corinne! What methods / products would you recommend to seal in the wood pesticides? I’m guessing that the paint that Pella uses on the wood isn’t sufficient to seal in the pesticides? I am leaning towards Pella wood (it’s within my price range and available in the south eastern US), so that’s good to hear that the pesticides are minor—but of course would be great to seal them in.

        Reply
        • Corinne Segura, Building Biologist

          August 26, 2024 at 1:20 pm

          I mention them in the article though if it’s already painted that is already a partial seal, especially if it’s a thick factory paint

          Reply
  8. Jessica Pearlman

    July 10, 2024 at 11:09 am

    Hi Corrine,

    Thank you for your site. I am wondering about the vinyl components you mention toward the end of the article: gasket, window stops, jamb liners, and tracks. 1) Are these also rigid PVC (without pthalates and plasticizers). The material seems a little more flexible than the window itself. 2) you mention all window types may have PVC components. Is it possible to get aluminum or fiberglass windows without these PVC components?

    Thanks very much.

    Reply
    • Corinne Segura, Building Biologist

      July 10, 2024 at 10:36 pm

      im not sure, i have not dug into those parts that deeply. my aluminum windows had a rubber gasket which was partially exposed.

      Reply
  9. Windows

    April 17, 2024 at 3:31 am

    I have read there are often issues with aluminium windows and thermal bridging and therefore condensation and mould- what is your opinion?

    Reply
    • Corinne Segura, Building Biologist

      April 17, 2024 at 2:04 pm

      that’s why it needs to be thermally broken

      Reply
  10. Jeff

    March 14, 2024 at 5:28 pm

    Hi Corinne, you mention that Accoya is used in some window brands. Do you know of any other major brands aside from Loewen that use Accoya wood? Loewen’s cost for Accoya seems prohibitive.

    Reply
    • Corinne Segura, Building Biologist

      March 14, 2024 at 6:01 pm

      i only know of Loewen, it is going to be expensive with solid wood and with this specialty wood on top of that

      Reply
      • Jeff

        March 15, 2024 at 6:54 pm

        Thanks for the info Corinne! I found Arcadia carries accoya too but just as expensive as Loewen. Accoya costs more than double traditional wood windows. Whoa. Looks like a great product just too bad it’s that much more expensive. For regular wood windows, would Ecos Interior Air Purifying Varnish be another good option as a sealer to block the chemicals or would you say AFM Safe Seal is better at that? Should the sealer be applied under the paint as a first layer or on top of it as the final layer?

        Reply
        • Corinne Segura, Building Biologist

          March 15, 2024 at 9:40 pm

          AFM Transitional prime or a shellac/shellac based primer before the paint will form the best barrier.

          Reply
  11. Michelle Maczka

    February 22, 2024 at 1:33 pm

    Hi Corinne, I hope this question is related closely enough to the article. I’m trying to find a structural framing material for windows that I can tolerate. I’m re-doing a single hull fiberglass trailer where the windows leaked and the original pieces attaching the metal windows to the fiberglass are old dry-rotted wood. I’m terribly reactive to wood due to the terpines. Also, ideally I’d like less of a mold risk. I was thinking virgin HDPE plastic lumber (not composite), but now I’m reading it expands a lot with heat (I’m in the desert) and is fragile with stress. Any suggestions for a good material?

    Reply
    • Corinne Segura

      February 22, 2024 at 2:39 pm

      I dont know enough about building trailers to know

      Reply

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