• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Skip to footer
  • About This Site
  • About Me
  • E-Booklets
  • Resources
  • Consulting
  • Site Navigation

My Chemical-Free House

A Guide to Creating a Healthy Home

  • Healthy Building
    • Insulation
    • Windows & Window Treatments
    • Glues & Caulks
    • Grout & Mortar
    • Drywall
      • Drywall Mud & Wall Texture
    • Showers
    • Doors
    • Pressed Wood Products
    • Sheathing & Subfloor
    • Pipes
    • Alternative Building Systems
    • Non-Toxic Prefabs
    • Building for the Chemically Sensitive
    • How to Test Materials
  • Healthy Interiors
    • Flooring
      • Gym Flooring
      • Flooring Underlayment
    • Kitchen Cabinets
    • Countertops
    • Mattresses
    • Sofas
    • Leather Furniture
    • Desks and Chairs
    • Sealers
      • Paint
      • Mineral Paints
      • Linseed & Tung Oil
      • Natural Wood Pigments
      • Natural Plaster
      • Natural Countertop Sealers
      • Concrete Sealers
      • Wood Finishes
    • Bathroom
      • Bathroom Vanities
    • Rugs
    • Wallpaper
    • Kitchen Appliances
    • Heaters
    • Reduce Flame Retardants
    • Reduce New Home Offgassing
    • Reduce Fragrance & Smoke
    • Air Purifiers for VOCs
    • Cleaning Products & Air Fresheners
    • Personal Care Products
    • Green Certifications
    • Gift Guide
  • Exteriors & Gardens
    • Decking Materials
    • Deck Stains
    • Deck Cleaners
    • Exterior Paints
    • Sealant for Concrete Birdbaths
  • Tiny Homes & Trailers
    • List: Simple Homes & Shelters
    • List: Trailers & RVs
    • List: Emergency Housing
    • Cargo Van Conversion
    • All Metal Tiny Home
    • Simple Insulated Shelter
    • All Aluminum Travel Trailer
    • Cargo Trailer Conversion
    • Teardrop Trailer
    • Tiny House Systems
    • Flooring for Vans, Trailers
    • Composting Toilets
    • How to Offgas that New Car Smell
    • Building for Chemically Sensitivity
  • Mold Prevention
    • A Detailed Mold Preventative Build
    • How “High Performance” can Help Prevent Mold
    • The Causes of Mold in Tiny Houses
    • Mold Testing Overview
    • Ozone to Kill Mold
    • Air Purifiers for Mold
  • Extreme Sensitivities
    • Healing MCS – Interview with Solona
    • How I Recovered from Chemical Sensitivities
    • Emergency Housing for Chemical and Mold Sensitivity

Is Plywood Toxic? (Non-Toxic Alternatives)

November 9, 2021 by Corinne 24 Comments

This post provides an overview of the formaldehyde and formaldehyde-free glues used in plywood.

I look at the offgassing levels and rates of formaldehyde in various types of plywood so that you can choose the lowest VOC option and minimize offgassing in the home.

There are non-toxic plywoods as well as non-toxic alternatives to plywood listed here.

This post contains affiliate links. Upon purchase, I earn a small commission at no extra cost to you.

What is Plywood?

Plywood is an engineered wood product made up of thin layers of wood called “plies” glued together. Each layer is laid with the grain running in the opposite direction to the previous layer.

Where is Plywood Used in a House?

  • Often used as sheathing on the exterior of the wood framing of a house
  • Often used as roof decking
  • Often used as subflooring
  • Often used as the boxes of cabinets, and as structure inside sofas and other furniture
  • Sometimes used as an underlayment or the structure of countertops
  • Sometimes (rarely) used as interior walls
A stack of plywood of different thicknesses

Myths About Plywood

That it offgasses forever

Plywood made with phenol-formaldehyde rapidly reaches non-detectible levels. Plywood made with urea-formaldehyde offgasses for longer, but it is up to 60% of the way there in 30 days. Plywood made from urea-formaldehyde is generally avoidable (and should be avoided in my opinion).

That it is high in formaldehyde

Plywood made with phenol-formaldehyde is not high in formaldehyde since it rapidly reaches non-detectable levels. Interior furniture grade plywood (which can be made with urea-formaldehyde) needs to come in at 0.05 parts per million formaldehyde.

That it is toxic

Plywood made from phenol-formaldehyde is not technically toxic. Plywood made from urea-formaldehyde is also technically not considered toxic at 0.05 parts per million formaldehyde. But those with compromised detox systems can find this level to be toxic to them. Whether it’s toxic or not very much depends on how much plywood is in the room, the size of the room, airflow in the room, and the person that is being exposed to it.

Which Chemicals Offgas from Plywood

Overview of the Adhesives Used in Plywood

Phenol-Formaldehyde (PF) (aka phenolic glue) – Most of the plywood I see now is made with phenol-formaldehyde. The offgassing is much lower and in many products comes to a complete cure in a short amount of time.

Urea-Formaldehyde (UF) – This is the type of formaldehyde that offgasses at higher levels and for longer. When you think of furniture or flooring that is offgassing for many years it was likely made with urea-formaldehyde. The offgassing rate of UF plywood varies by the exact formula (also some companies use heat to accelerate the offgassing) – it can vary from 15-60% offgassed in 30 days (source). Remember the offgassing is on an exponential curve.

Melamine-Urea Formaldehyde (MUF) – This is a urea-formaldehyde glue modified with melamine and PVA. It gives the plywood more water resistance and is usually only used for exterior door skin, marine plywood, and concrete formwork plywood. Adding melamine reduces the formaldehyde offgassing levels (source).

No added Urea Formaldehyde (NAUF), this almost always means PF is used.

No Added Formaldehyde (NAF), this means that no formaldehyde is added to the product – the glue used does not contain formaldehyde. They cannot be labeled “formaldehyde-free” because wood naturally contains formaldehyde. No added formaldehyde plywood is made with “soy-based” glue.

Soy-Based Glue – Soy-based glue is not just one formulation. They use soy protein mixed with polyamidoamine-epichlorohydrin (PAE), isocyanates, and aldehydes. (From the co-inventor of the adhesive for Purebond Plywood). This one is called soy-PAE. A similar type of soy-based glue that may be used to replace formaldehyde in MDF and particleboard is an amine-epichlorohydrin adduct/soy protein/isocyanate (source).

a close up of the veneer on a plywood sheet

Types of Plywood and Their Glues

Structural Plywood

Structural plywood is softwood plywood (SWPW) and it is used for roof sheathing, subfloors, and roof decking.

This type of plywood is made with phenol-formaldehyde as the binder/glue (3.5% formaldehyde to be exact). Phenol formaldehyde is the least toxic type as it offgases less than urea-formaldehyde and it off-gases faster.

Formaldehyde Levels

Formaldehyde levels in freshly produced plywood start out below 0.1 parts per million (ppm). But “emissions rapidly approached zero as the panels aged. In fact, the levels were so low and so close to the ‘background’ levels in the test chamber that it was not possible to measure them accurately” according to the American Plywood Association.

While the APA would not say exactly when the PF levels approached zero (or close to it), I do think that a few weeks is more than adequate for most people.

For most people, exterior plywood in a build will be sufficiently offgassed by the time the building is complete.

Testing Your Reactions

If you are extremely sensitive you should test out plywood when new, after a few weeks, and after 2-3 months of airing. You should also compare that to OSB, to see which is better for your health (I certainly prefer plywood to OSB). The extremely sensitive can often pick up the residual odor of the plywood glue even after the point where it’s undetectable by any instrument. It also becomes difficult to tell where the formaldehyde from the glues ends and the natural level of formaldehyde in the wood starts if you are sensitized to it.

Marine-Grade Plywood Glues

In the US, the marine-grade plywood I’ve seen is made with phenol-formaldehyde, but it can also be made with melamine-urea formaldehyde.

This is not a specific type of plywood in Canada.

Pressure-Treated Plywood Additives

Pressure-treated plywood is commonly treated with alkaline copper quaternary (i.e. copper and quaternary ammonia) (ACQ).

Copper Azole (CBA) is another type, which contains copper, tebuconazole, and possibly boric acid.

Though some wood is still treated with chromated copper arsenate (CCA), this is rare nowadays and it’s definitely not often used in residential buildings.

Product Certification Levels for Formaldehyde

A chalkboard looking graphic that says formaldehyde CH20

CARB II – Formaldehyde Levels CARB II is a standard set by California for products sold there, but when it comes to common building materials like plywood, all major manufactures tend to comply with California’s standards.

Products that fall under this standard include hardwood plywood, medium-density fiberboard, and particleboard – these are pressed wood products sold for interior use.

It does not regulate exterior sheathing products like structural plywood (softwood plywood) and OSB.

(The allowable limits for TSCA Title VI are the same as CARB).

CARB II Formaldehyde Limits Are: Hardwood Plywood 0.05 ppm (parts per million.

The CARB II limit is the same as the GreenGuard limit (not Gold).

Furniture Grade Plywood

Interior grades of plywood can be made with urea-formaldehyde as the adhesive. Urea-formaldehyde (UF) offgasses more and for longer. Now phenol-formaldehyde (PF) is more standard, but I still see some SDS sheets showing urea-formaldehyde.

Interior plywood is often called furniture grade or hardwood plywood. You will want to make sure your furniture is made with PF or NAF glues, not UF.

Formaldehyde-Free Plywood

1. Purebond Plywood by Columbia Forest Products is a no added formaldehyde plywood (NAF). It is made with a soy-based glue.

When folks talk about formaldehyde-free plywood, this is the one they are usually referring to.

Their adhesive is partially proprietary, but they claim it is “soy-based”. The full Declare label is here but this doesn’t tell us much about what it will offgas in the end, only what went into it.

I have seen extremely chemically sensitive folks react to this brand of plywood so I would make sure to test it out yourself before using it. I do think the odor is extremely mild and unoffensive.

Purebond plywood is intended for interior uses like furniture and cabinets (here are some cabinet makers who use Purebond). It is not structural and it is not made to hold up to high humidity or moisture. Some folks are using this as sheathing and roof decking which is a very bad idea.

You can buy it at Home Depot.

2. SoyStrong Hardwood Plywood is another brand of formaldehyde-free plywood made with a soy-based glue.

You can buy it at Lowes.

How to Offgas Plywood & Seal in the Formaldehyde

1. Give it Time to Air Out

Stack your plywood in a garage or covered area in a way that allows each piece to have some airflow.

Time, heat, and air are the main ways to allow any material to offgas.

2. Seal it

Whether you should seal your plywood partially depends on where it will be going.

If it’s on the interior of your home, then no problem, seal away.

Exterior applications, like wall sheathing and roof decking, are trickier. Wood naturally has the ability to absorb and release moisture. Stopping that natural process could cause problems.

To seal plywood there are a few ways you could go, but the two main options are AFM Safeseal which is a clear acrylic-based coating that helps to block and seal in formaldehyde, or shellac which is an alcohol-based natural wax coating. Shellac does a slightly better job at sealing.

someone brushing on a milky-clear sealant on plywood to seal in the formaldehyde

Alternatives to Plywood, Which Are Less Toxic?

1. Formaldehyde-free plywood is a good non-toxic alternative to regular plywood in most interior applications and in furniture.

2. OSB is often used in place of plywood in structural applications. I don’t consider OSB to be less toxic, as it has higher offgassing and takes longer to come to completion but it’s possible that it works better for some people since the glues are different.

3. XPS foam can replace plywood as wall sheathing (but it’s probably not a good idea in most situations).

4. MgO board can sometimes be used as the subfloor and other sheathings (and I even used it for cabinet boxes and countertop underlayment).

5. Solid wood can replace plywood in some applications, like purlins or skip sheathing on a roof, in subflooring and sheathing, and for cabinet boxes and most furniture.

6. Georgia-Pacific DensGlass can replace plywood sheathing in some areas.

7. Cement board is sometimes used as sheathing, especially in tropical areas. Another concrete-based board, USG Structural Panel, is a thick and very strong board, it is sometimes used on foundation walls when the framing is metal.

8. Drywall is generally zero-VOC so it is technically less toxic than plywood but there are not many instances where they are interchangeable. If plywood is an option for your walls then you may prefer to use drywall.

Corinne Segura is a Building Biologist Practitioner with 8 years of experience helping others create healthy homes.

Buy Me a Coffee at ko-fi.com

Sources

https://pharosproject.net/common-products/2078999#contents-panel

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6723320/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6723320/

Filed Under: Healthy Building, Healthy exteriors/gardens, Healthy Interiors

Reader Interactions

Comments

  1. Kelly says

    March 17, 2023 at 7:12 am

    Have you possibly looked into Murphy Plywood or do you have any thoughts on what they have to say here about formaldehyde? https://www.murphyplywood.com/questions-and-answers/

    Reply
    • Corinne says

      March 17, 2023 at 12:59 pm

      Yes that’s accurate, structural plywood is low in formaldehyde and doesn’t need to be CARB. You should look for APA.

      Reply
  2. Nick says

    February 28, 2023 at 2:40 am

    Hello Corinne,

    I have a question for you regarding interior plywood usage. I’ve recently used 18mm shuttering ply for the interior walls of a workshop/studio and have discovered via the internet that there might be an issue with off-gassing (although I have felt no effects). I had to use a couple of different brands of plywood and can’t be sure what the glues used were. In total I used around 20 – 25 sheets (quite a substantial amount). They’ve been in there for about 6 months, from your article am I right to understand there should no longer be an issue? I frequently have the doors and windows open and by the sounds of it that’s the best way to get any possible formaldehyde levels down.

    Thank you for the informative website.

    Nick

    Reply
  3. Nick says

    February 28, 2023 at 2:37 am

    Hello Corinne,

    I have a question for you regarding interior plywood usage. I’ve recently used 18mm shuttering ply for the interior walls of a workshop/studio and have discovered via the internet that there might be an issue with off-gassing (although I have felt no effects). I had to use a couple of different brands of plywood and can’t be sure what the glues used were. In total I used around 20 – 25 sheets (quite a substantial amount). They’ve been in there for about 6 months, from your article am I right to understand there should no longer be an issue? I frequently have the doors and windows open and by the sounds of it that’s the best way to get any possible formaldehyde levels down.

    Thank you for the informative website.

    Nick

    Reply
  4. A. Owens says

    January 30, 2023 at 7:00 am

    Thanks for this currently considering builtin plywood bed for kids room.

    Reply
  5. Diana says

    January 2, 2023 at 7:47 pm

    Hi dear! What should i use under ward wood flooring? I guess i can put under some natural rubber? Or still plywood, what kind1 . As well about glue, i need for bathroom. I saw your post of glues but still can’t get which one is best and for water resistance

    Reply
    • Corinne says

      January 3, 2023 at 11:17 am

      There is a post on underlayment that will help. I wouldn’t glue down wood flooring but there is a glue recommendation in the post on engineered wood.

      Reply
      • Dian says

        January 4, 2023 at 10:43 pm

        Thx. But wood floor is 7 wide x 25 long, how you will install this option, thank you.

        Reply
        • Corinne says

          January 5, 2023 at 11:43 am

          Oh I see, check out the glue options in the post on engineered wood.

          Reply
  6. Chris says

    September 26, 2022 at 9:14 pm

    Hello,
    What would you suggest for a bunkie board to go underneath a non-toxic latex mattress for a child? We bought regular plywood and we have to take it back and get something else non-toxic because we could smell it in the room. Thank you

    Reply
    • Corinne says

      October 10, 2022 at 2:57 pm

      I wouldn’t put a mattress on a flat board because of condensation and mold. If it’s an air mattress or something that can’t mold, use one of the plywoods recommends in the post – the soy ones.

      Reply
      • J says

        December 17, 2022 at 3:16 pm

        Full Latex mattresses must be placed on a flat surface.

        Air mattresses can/do mold

        Reply
        • Corinne says

          December 22, 2022 at 12:59 pm

          Well anything can mold in the right conditions. If the air mattress is over a concrete floor that is taking on water outside and drying to the inside then you will probably find mold under it.

          but it doesn’t transfer body sweat like most mattresses do which can lead to mold under it on any flat surface/on any wooden floor.

          the bases for latex mattresses have slats. you shouldn’t put a thin piece of latex on a flat surface. Go with one of the good brands like avocado that go on slats.

          Reply
  7. Rachel says

    June 20, 2022 at 11:19 pm

    Hi Corrine, I thought the phenol resin glues in plywood incorporate BPA, is that correct? It seems it is quite hard to know what exactly is in the glue. Thank you Rachel

    Reply
  8. Tami says

    June 5, 2022 at 5:57 pm

    What about birch plywood, would you say this is safe? ( after the 30 days)

    Reply
  9. Gillian Whittall says

    April 27, 2022 at 5:35 am

    Fantastic blog, please keep up the good work and the fight to get this awful stuff out of our homes! I recently bought a recliner sofa and in two hours, my nose and eyes were streaming. Even though companies claim ‘Solid Wood Frame’, all the panels of the arms, the backs, were all plywood and composite board. The company that sold it were good enough to take it back but we lost our deposit. I think it’s a disgrace that companies are shoving this stuff into our homes when it should come with a toxic warning label, particularly for those with respitory issues. Urea Formaldeyde is carcinogenic. I’m not sure about the other versions you have listed here. I wish I could find a sofa manufacturer that does not use this stuff and uses only hardwood.

    Reply
    • Corinne says

      April 27, 2022 at 1:49 pm

      Ya this is a problem – saying solid wood and then it being engineered wood. I guess they are hoping no one looks inside it, though you can often see it from underneath.

      Reply
  10. Lisa Samalin says

    March 29, 2022 at 7:04 am

    Dear Corinne,
    We moved into a house that was built in 2007 a few months ago and i haven’t been feeling well. When we moved in we ripped up carpeting in 3 rooms including the bedroom and painted the plywood subfloors with latex paint. have a long history of being extremely sensitive to substances and I’m wondering if the plywood could be an issue. If so would you have any suggestions how to remedy it? I so appreciate anything you can tell me. Thank you, Lisa

    Reply
  11. Monika says

    March 22, 2022 at 7:07 am

    Hi Corinne, I was wondering if you know of this brand and what your thoughts are on it. Would you say any shellac sealer would do or there would still be differences in sealing properties?

    https://chestnutproducts.co.uk/product/shellac-sanding-sealer/

    Thank you!

    Reply
    • Corinne says

      March 22, 2022 at 2:01 pm

      Any brand will do.

      Reply
      • Monika says

        March 22, 2022 at 2:29 pm

        Thank you so much!

        Reply
        • Monika says

          March 23, 2022 at 6:51 am

          Do you think Osmo hardwax oil would also seal plywood from off gasing?

          Reply
          • Corinne says

            March 23, 2022 at 2:17 pm

            No, first it’s high in solvent odor itself and two it’s a breathable sealer so it won’t seal in offgassing. We want the opposite, not breathable.

  12. RobertHan says

    March 5, 2022 at 9:34 pm

    Nowadays, high-quality plywood or plyboard products are widely used and available in the market to install or replace my floorings. Thank you for your writing page. It helped me a lot

    Reply

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Primary Sidebar

Stay up to date with the Latest!

  • Facebook
  • Instagram
  • YouTube

ABOUT ME

Hi, I’m Corinne Segura, I hold a certificate in Building Biology, and a certificate in Healthier Materials and Sustainable Buildings, among other credentials below. I have 8 years of experience helping people create healthy homes.

More about my educational credentials

Footer

Sitemap

Amazon Affiliate Disclosure: As an Amazon Associate I earn from qualifying purchases.

Privacy Policy, Disclaimer, Disclosure

Do Not Sell My Personal Information

Resources

Business inquiries

Copyright © 2023 · Corinne Segura | My Chemical-Free House Consulting