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My Chemical-Free House

A Guide to Creating a Healthy Home

  • Healthy Building
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      • Drywall Mud & Wall Texture
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    • 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

Guide to Non-Toxic Drywall: Types and Brands

July 11, 2019 by Corinne 35 Comments

Drywall is also called gypsum board, sheetrock, plasterboard, or more generally, wallboard. We are going to look over the types and brands, and which chemicals they contain. Which ones have the least toxic additives, don’t offgas, and are the healthiest choices.

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

What is Drywall Composed of?

The main ingredient in drywall is gypsum, so let’s start there and look at the health considerations of gypsum. There are two types of gypsum:

Natural gypsum mineral crystals

Natural Versus Synthetic Gypsum

Natural gypsum is a product mined from the earth. Synthetic gypsum is made from the byproduct of power plants, also called FGD gypsum. They are both technically gypsum.

Unless a product specifically states they use natural mined gypsum, it is exceptionally difficult to track which brands use which type, or if they use a mix.

  • 30% of all drywall in North America is synthetic
  • USG, the largest drywall manufacturer, has 21 drywall plants. 9 of those only use synthetic. 6 use a mix of the two source

What Else is Drywall Made Up Of:

  • Drywall is 70-90% gypsum (synthetic, mined or mixed)
  • 10% paper, on the paper-backed types

Other additives that may be included:

  • Cellulose fibers (in monolithic drywall)
  • Fiberglass fibers (fiberglass is in X and C types, and fiberglass backed drywall)
  • Plasticizers
  • Starch
  • Finely ground mica crystal as an accelerant
  • EDTA or other chelating agents
  • Boric acid/borates
  • Wax like paraffin or hydrocarbon, or silanes to hinder water absorption (on the greenboard types)
  • Potassium sulfate
  • Sodium sulfate
  • Vermiculite (in Type C fire resistant drywall)
  • EVA as an adhesive

Source 1, source 2, and SDS sheets

Does Synthetic Drywall Contain Mercury?

Both synthetic and natural gypsum contain low amounts of mercury. It is regulated by the UL standard (ULE 100).

How Much Mercury is in Drywall?

The amount of mercury in synthetic gypsum varies depending on the power plant it came from (source).

It is also a trace metal found in natural mined gypsum. One study found the amounts were 0.92 ng/m2-day for natural gypsum wallboard and 5.9 ng/m2-day for synthetic gypsum wallboard. This resulted in mercury levels in the rooms that were below the background levels normally found indoors and within or below the levels found in outdoor air (source).

Therefore, mercury in drywall has not been a concern of mine. If you wanted to avoid all gypsum board you would be looking at alternatives like MgO board, tongue and groove wood (not allowed by all codes due to fire risk), or plaster and lath (wood or metal lath).

Or, you could minimize the amount of mercury by going with natural gypsum.

USG, Georgia-Pacific, CertainTeed and National Gypsum are the main producers of gypsum board. These are all easy to source at building supply stores and through contractors. The gypsum could be natural, synthetic, or mixed, and it’s very difficult to find out which drywall line contains which type of gypsum.

Non-Toxic Drywall

A stack of drywall

By Brand:

1. Natural Gypsum

National Gypsum makes gypsum boards that are VOC-free (the paper-backed ones). This brand tends to use natural gypsum.

Their standard line is the regular Goldbond. LITE may also work well for sensitive folks. More on “light” drywall below. The type X is a fire-rated drywall, it contains fiberglass.

You can source this through your contractor’s suppliers. You can get a test sheet at Lowes.

The use recycled paper to back the drywall (like the other major brands).

2. USG SheetRock

This is the largest drywall brand and the easiest to source. The SDS sheets claim 0-VOC. They also have GreenGuard Gold certification, which I discuss more below.

The “regular” drywall should contain the least amount of additives. They use recycled paper backing and facing, but there should be no mildewcide, fiberglass, or other major additives.

USG Sheetrock Ultralight – I have been happy with their Sheetrock Ultralight, I did not pick up any offgassing or moldiness in the paper. Although we don’t know what the blowing agent is (it could be air), I would feel comfortable using this one in my home due to my own testing of it. This is my go-to brand that I specify.

This one is inexpensive and easy to find. You can get it at Home Depot or through your contractor.

USG Firecode X – Research that a very sensitive client revealed that USG was the cleanest gypsum on the West Coast (as it contained more natural gypsum). Though these things change over time, and that same brand could be made in a different factory on the East Coast.

It does not contain a flame retardant, it does contain glass fibers (fiberglass). More on type X below.

3. Georgia-Pacific

Georgia-Pacific Gypsum boards are all GreenGuard Gold Certified. Their exact VOC levels are not listed on the SDS.

Like the other brands, they have a “standard” line which is what I would recommend as the safest bet. The “light” can be considered as well.

GP DensArmor Plus is the most popular fiberglass-backed drywall. No paper here. They recently made a statement that the Dens line is treated with biocides.

4. Certainteed

CertainTeed Gypsum boards claim zero-VOC (no reportable VOCs), and they have GreenGuard Gold certification.

They have all the same categories of drywall types as the others.

Should You Use Paper-Backed or Fiberglass-Backed?

A close up of USG Glass mat liner which is a fiberglass backed gypsum board
USG Glass Mat Liner

Many drywall companies use recycled paper which some folks are reluctant to use in their homes. One study showed that paper is already full of mold spores (source). The other concern is that if it gets wet it will mold faster than other materials.

If that is a concern of yours, I would check out the fiberglass-backed drywall and see if that is tolerable for you. Fiberglass is not totally odorless.

If it isn’t, keep in mind that you should not have moisture or condensation behind your wall if your wall is designed and built right. If you have a big leak you are likely to find that quite quickly. I would not rule out paper-backed drywall, personally.

A close up of USG fiberlock which is a monolithic drywall
USG Fiberock

Another type of drywall is called monolithic drywall (pictured above)- no paper and no fiberglass – such as the USG Fiberock line.

It does not have a backing, instead, it contains cellulose fibers dispersed throughout the gypsum. This is a less common type. If you have chemical sensitivities you should test it out yourself if you rule out the other two types. This is my top pick for the type of drywall to use on the bathroom walls (not behind tiles, just the walls).

You do need to skim coat this type of wallboard (same goes for fiberglass backed).

Behind wet areas, concrete backer board should be used (not drywall) – that is discussed in the post on bathrooms.

Costs? Paper-backed drywall is the least expensive type, followed by fiberglass-backed, and then monolithic.

Types of Drywall with Special Properties – Which Chemicals are Added?

1. Fire-Rated Drywall

Type X drywall means it meets requirements for fire codes (that could be required in certain rooms of a house). This type contains glass fibers, is denser, and is 5/8th thick (regular drywall is ½ inch).

It is 10-20% more expensive than regular drywall.

Type C is another type of fire-rated drywall, with a higher rating than type X. It also contains fiberglass and a form of vermiculite. It is more expensive than type X and may be specified for certain areas.

a close up of the gypsum board USG Sheetrock Firecode X
USG Sheetrock Firecode X

2. Drywall that Reduces Formaldehyde

CertainTeed’s AirRenew (GreenGuard Gold), claims to soak up formaldehyde. However, it also contains a biocide.

It is a little harder to source than the ones above. In Canada, you can find it at Lowes. Some have reported an odor with this one that might indicate that an additive used to soak up formaldehyde might not work for everyone.

This patent might be related to this brand.

3. Light Drywall 

The major drywall companies all have lines that are lighter in weight, and these are very commonly used in construction. We don’t know what is added to light drywall that makes it light.

From my testing of it, I did not find that it had chemical offgassing, but we don’t know what the blowing agent is – it could be air or something that dissipates quickly (source).

I did well with USG Sheetrock UltraLite, and I don’t suspect a toxic blowing agent.

Borates are likely to be found in light drywall (source). The SDS will sometimes list borax.

a close up photo I took of USG ultralight edge where you can see the paper backing and the gypsum with lots of little bubbles
USG Ultralight has lots of air bubbles

4. Mold Resistant Drywall / Green Board

Both the monolithic (homogenous) drywall and fiberglass-backed types are less prone to going moldy (or at least to going moldy as quickly) compared to paper-backed drywall.

Fiberglass-backed drywall is promoted as more mold-resistant, but all of the brands I have looked at including the Dens line do contain a mildewcide.

If it is labeled as “mold-resistant” and is paper-backed then you can expect a biocide.

Paperbacked brands with mildewcide in them include:

  • Georgia-Pacific’s ToughRock Mold Guard (unclear what it is treated with)
  • Certainteed’s M2Tech (unclear what it is treated with)
  • National Gypsum Goldbond XP (treated with thiabendazol, azoxystrobin and fludioxonil)
  • USG Sheetrock Mold Tough line (treated with sodium pyrithione)

“Green board” is a generic term for green-colored drywall like these that have biocide treated paper and are meant for areas with more moisture.

GP’s ToughRock Mold-Guard, American Gypsum’s Aquabloc, and Sheetrock Mold Tough are green board. Purple drywall by National Gypsum is similar.

A bathroom with greenboard that is mudded at the seams but not yet painted
Greenboard

Additional Health Concerns with Drywall

Green board

All the parts to the wedi shower system with the base board and membranes

It is not best practice to use green board (including the purple) behind tiles that get wet.

Best practice in this area is to use concrete backer boards with the Schluter system, or Schulter or WEDI foam boards, discussed in this post on bathrooms.

If you want to create a mold preventative shower, Schulter and WEDI are the best systems.

Using green board behind wet tiles can lead to mold if there is moisture. They also contain added mildewcides, so I prefer to avoid these types of drywall.

Sulphur Emitting Drywall

Small rocks of sulfur

The “Chinese Drywall” debacle is the best-known case of a major problem in the drywall industry. Between 2001 and 2009 some drywall offgassed sulfur to the point of causing major problems.

There have also been lawsuits against American-made drywall, but they were dismissed.

I have not seen any issues with sulfur and drywall lately.

In every industry, these kinds of problems do crop up from time to time. Those very sensitive should use their own reactions to guide them. Drywall should never smell like sulfur, and if you react to it that won’t be good for you.

Those who are healthy or less sensitive should go with well-respected brands and do the best you can with the research that we have. Made in America may be better, but is no guarantee that there will not be problems.

The problematic drywall also contained strontium.

Silica Dust 

A box of 3M N95s

When drywall is cut and when joint compound is in dust form (straight out of the bag or after sanding), silica, the same substance that glass is made of is, is harmful to breathe in.

Silica is perfectly safe when in solid form.

Be sure to take great caution when mixing up drywall mud, when cutting drywall and when sanding the mud.

Use an N95 mask or better when around the dust.

The dust is very fine and difficult to remove, I have seen it in builds that are 2 years old. It clings to the wall so you have to clean it very thoroughly.

Make sure the central HVAC is off when drywall and drywall mud work is being done, there should never be drywall/silica dust in your ducts.

Products containing silica dust/quartz will have a Prop 65 warning, keep in mind it’s safe when in solid form.

Should your Drywall be Certified – GreenGuard Gold or UL?

The greenguard gold logo

The only benefit to a GreenGuard Gold product is it might catch these unusual problems with offgassing that have cropped up – either sulfur or formaldehyde.

More than a decade ago, some drywall did test positive for formaldehyde, in that sense, GreenGuard Gold is the best certification for this case, as it ensures the VOC levels are extremely low, the same as outdoor air. More details on GreenGuard levels in this post on certifications.

Those who do not want to over-research should go with a big brand Greenguard Gold line that does not contain mildewcides. National Gypsum Goldbond if you want natural mined gypsum.

Drywall should be zero-VOC, and in theory, does not give off formaldehyde at a detectable level.

UL 100 is somewhat helpful in that it regulates mercury, but I expect all drywall to have extremely minuscule levels of mercury.

For drywall mud (spackle/joint compound), drywall tape, and mud for textured walls see my dedicated post on this topic.

Related posts:

Non-Toxic Drywall Mud

Non-Toxic Plaster

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

Did you find this post helpful? If so you can buy me a coffee to support the research behind this blog. Thank you!

Buy Me a Coffee at ko-fi.com

Sources:

1) Building Green


2) The Spruce


3) SDS sheets for all the major brands


4) Teledy


5) Pub Med


6) Research Gate


7) Patent


8) The Spruce


9) Borax


10) ProPublica

Filed Under: Healthy Building Tagged With: Healthy building

Reader Interactions

Comments

  1. Sarah says

    January 14, 2023 at 2:52 pm

    Corrine. My husband and I recently used the USG Sheetrock Ultralight and the room has had a horrible damp cardboard kind of odor since it was installed. (We haven’t had the mudding done yet.) We have no moisture issues of any kind in that room or in the house as we are mavens about indoor air quality, humidity, etc. Any thoughts on what could be going on?

    Reply
  2. Peoria Drywall says

    January 8, 2023 at 3:23 am

    Excellent advice!

    Reply
  3. Flex Drywall Repair says

    July 14, 2022 at 1:08 pm

    “Useful post” Thank you so much for the detailed post from start to end about Drywall.

    Reply
  4. Diane Ibsen says

    April 30, 2022 at 5:36 pm

    Hi Corinne. So glad that you are part of the solution. That you have MCS and that you understand. I’ve been sick for a very long time and it has affected my quality of life, and my finances terribly. I was approved for Section 8 Housing Voucher finally after being homeless for 3 years..or more. Anyways, I am looking for help finding and a suitable place to live for now at least. The voucher is for King County. I can “Port eventually” but it does take several months. I’m close to 55 and so could qualify for 55 up property. I’m wondering if you have any ideas or suggestions for me? I would so appreciate it if you do. Thank you, Diane

    Reply
  5. Tami says

    September 6, 2021 at 10:19 am

    Also what about drywall mud and tape? Is this also an issue for those with MCS? Is there any you recommend. Kinda leaning to the wedi board with tile to fix issue but would love your take on it. THANK YOU!!!

    Reply
    • Corinne says

      September 6, 2021 at 3:44 pm

      Here is the post on drywall mud https://www.mychemicalfreehouse.net/2020/05/non-toxic-drywall-mud-and-wall-texture.html

      Reply
    • Robert Haverlock says

      January 31, 2022 at 1:39 pm

      Murco 100

      Reply
  6. Tami says

    September 6, 2021 at 10:06 am

    Hi Corinne,
    We are redoing our bathroom and damaged drywall on bottom half of wall. Trying to consider healthier option if purchasing Wedi board and tiling half way up around wall , OR replace drywall. Thank you for such informed information always appreciated!!!

    Reply
  7. Heidi McLaughlin says

    June 14, 2021 at 11:25 am

    The USG Ultralight components are listed at:
    https://hpdrepository.hpd-collaborative.org/repository/HPDs/90_Sheetrock_Brand_UltraLight_Panels.pdf

    These contain formaldehyde and an undisclosed tensile strength additive. No foaming agent is listed.

    Reply
    • Corinne says

      June 14, 2021 at 2:51 pm

      I don’t believe that the final product gives off formaldehyde at a detectable level.

      Reply
  8. Rita says

    May 17, 2021 at 8:35 am

    The link to the National Gypsum Goldbond says the product is no longer available. When I look at National Gypsum’s site, it’s very confusing as they offer a ton of wallboard in that series. Some is fire resistant, others is mildew resistant. Can you offer a link to which board on their site you recommend, so I can try to figure out if local suppliers have that exact one.

    Reply
    • Corinne says

      May 21, 2021 at 10:51 am

      The links in the article are working for me. They have lite and regular which are the most basic ones.

      Reply
  9. Sarah says

    January 13, 2021 at 10:32 am

    Thank you for this very helpful post. I am doing a reno at my house in Texas and thought I would share that I reached out to USG about their drywall. They told me that the drywall coming from their Sweetwater, TX plant is all natural. So if you are able to source from that plant, you should be getting natural gypsum. Hopefully this is helpful to others.

    Reply
    • Corinne says

      January 13, 2021 at 10:38 am

      Thank you!

      Reply
  10. Ana says

    January 9, 2021 at 8:57 pm

    What type of drywall would you recommend for a basement? It seems that you don’t recommend green boards?

    Reply
    • Corinne says

      January 11, 2021 at 12:15 pm

      Ideally the basement walls are unfinished (painted or plastered concrete). I personally would not finish them out. But if you do it should be designed in a way that regular drywall will work just fine. For high humidity I have a slight preference for fiberglass backed over green board as green board still has the paper but it is soaked in more chemicals. I don’t think that is the solution in any situation for high humidity. There are also construction methods to keep the drywall off of the floor in case of flooding.

      Reply
  11. Jessica A Pearlman says

    December 18, 2020 at 1:42 pm

    Hi Corine, I just spoke with National Gypsum. It sounds like they do still use synthetic gypsum although they are phasing it out.

    —Jessics

    Reply
    • Heidi McLaughlin says

      June 14, 2021 at 11:12 am

      National Gypsum uses synthetic at some of their facilities and not at others, depending on the availabilities of raw materials. The PA plant has a high synthetic component in their panels, the New England area panels are majority natural. You’d have to let them know where you are purchasing to get a correct answer.

      Reply
  12. Joan says

    December 10, 2020 at 11:53 am

    My contractor is using USG compound that is dustless. I have been having burning sinuses, sore throat, bad headache now for almost a week. What could it be that’s causing this?

    Reply
    • Corinne says

      December 11, 2020 at 9:53 am

      The premixed compound definitely offgasses.

      Reply
  13. Paula says

    November 12, 2020 at 8:11 pm

    I’m unclear about your stance on mildewcides and your section on “Mold Resistant Drywall”… are you recommending those? Or not, because they contain mildewcides? Mold is bad, but aren’t mildewcides also “bad”? If so, what type of drywall should be used in areas like an untiled bathroom?

    Reply
    • Corinne says

      November 13, 2020 at 1:04 pm

      They are not great, but they’re also not the worst chemical out there. I would prefer to use concrete backer board in almost all situations.

      Reply
      • Paula says

        November 13, 2020 at 2:24 pm

        It’s my understanding concrete backer board is for use behind tiles…but I’m using acrylic surrounds for my showers and I’m not tiling my remaining bathroom walls. Concrete backer board can’t be used in place of drywall for entire bathroom walls (that aren’t behind showers), can it?

        Reply
  14. Ali says

    August 3, 2020 at 5:58 pm

    Hi there, so over all-would you day USG is safe to use? And I can not find where it states that they have green guard gold cert? Any ideas where they may have that listed? Are all types of USG safe or only specific lines? Thanks so much!

    Reply
    • Corinne says

      August 3, 2020 at 7:17 pm

      The drywalls I checked out by USG are well below Greenguard gold. There are some slight variations of the gypsum between factories but the other ingredients will be the same across that brand. https://usg.gcs-web.com/news-releases/news-release-details/usg-earns-greenguard-gold-certification

      Reply
  15. elije burge says

    March 15, 2020 at 8:41 am

    hempcrete with lime wash and clay based skim, non toxic , environmentally friendly big time, and self healing

    Reply
  16. Michael says

    March 10, 2020 at 8:46 pm

    So Lowes carries the only natural gypsum which I guess is the best stuff to go with for MCS? The link you provided says it’s a fireshield panel? So this has fiberglass? I’m so confused.

    Reply
    • Corinne says

      March 11, 2020 at 7:20 pm

      National Gypsum has lines that are regular, lite and fire rated. The fire rated types do have fiberglass.

      Reply
      • Michael says

        March 12, 2020 at 6:52 pm

        Thank you for your reply. So would the lowes brand, National gypsum(or goldbond?) be natural gypsum and therefore the best choice as far as drywall for MCS people?

        Reply
  17. Stacey says

    February 25, 2020 at 12:20 pm

    Has anyone tested USG Fiberock Monolithic Drywall for detectable off-gassing? Curious to hear people’s feedback. If not, other than potentially price, it seems like there’s no downside?

    Reply
  18. Anna says

    November 10, 2019 at 5:27 am

    People buy these mold resistant drywall units and then use regular joint compound or paper tape. That never made sense to me. Why spend extra on your special mold resistant drywall if the joint compound and paper tape is predisposed to mold…

    Schluter system is the most logical thing you can do. I was about to purchase MgO or DensArmor Plus boards for a higher humidity room and in areas directly behind sinks, and then I was baffled by zero selection of mold resistant joint compounds. It logically made no sense to me to invest in this mold resistant drywall only to get mold prone joint compound. And if I did decide to go with a mold resistant joint compound with a fiberglass tape (to truly make it a mold resistant system), then I would have a biocidal chemical product, which would defeat the purpose of my non toxic theme home. That's when I started to read up on the Schluter system for showers and tubs and Caliwell paint in higher humidity rooms of the house.

    Reply
  19. Corinne says

    September 17, 2019 at 6:42 am

    There is no special drywall mud for bathrooms. Your humidity should not stay over 60% for long periods of time though.

    Reply
  20. Anna says

    September 13, 2019 at 11:08 pm

    What type of drywall mud is compatible in high humidity areas?

    Reply
  21. Anaphylaxing says

    January 25, 2015 at 5:13 am

    Love this post. Aerated Autoclaved Concrete appeals the most to me. They can ship it to Canada but the trucking fee was significant.

    Reply
    • Corinne says

      January 25, 2015 at 5:14 am

      that's good to know!

      Reply

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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.

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