Guide to Non-Toxic Drywall: Types and Brands

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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.

"Mudding Sheetrock" by Forest Service - Northern Region is licensed under CC BY 2.0 

For assistance with choosing the best wallboard for your needs, sensitivities, and budget, you can contact me for a one-on-one consult. 


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 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

natural gypsum mineral

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 may be included such as:
  • Cellulose fibers (in monolithic types)
  • Fiberglass fibers (fiberglass in X and C types, and fiberglass backed drywall)
  • Plasticizers
  • Starch (to adhere the paper to the drywall)
  • 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
  • Vermiculite (in Type C fire resistant drywall)

Source, 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 major concern of mine in the past. If you wanted to avoid all gypsum board you would be looking at alternatives like MgO board, covered here, 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.

Non-Toxic Drywall – Types & Brands


Natural Gypsum

nationalgypsum.com
National Gypsum makes natural gypsum boards that are VOC-free (the paper backed ones).

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.

I would rather not have recycled paper-backed drywall. But the other major brands also use recycled paper.

Synthetic Gypsum (and Mixed)


USG, Georgia-Pacific and CertainTeed are the three main drywall producers in North America along with National Gypsum above. These are all easy to source at all 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.

USG SheekRock

usg.com
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 (in all the brands). They have the recycled paper, 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, I would feel comfortable using this one in my home due to my own testing of it.

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 did 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.

Georgia-Pacific 

buildgp.com
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" 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.

Certainteed

certainteed.com
CertainTeed Gypsum boards claim 0 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?


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 has some offgassing.

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.

USG Fiberock Monolithic Drywall
Another type of drywall is called monolithic drywall - 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 more unusual type, but you should try and test this out for your needs, if you have to rule out the other two types.

Paper backed is the least expensive type, followed by fiberglass backed, and then monolithic.

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

Types of Drywall with Special Properties – Which chemicals are added?


Fire Rated Drywall


USG SheetRock Firecode C
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.




Drywall that Reduces Formaldehyde


Certainteed AirRenew
CertainTeed’s AirRenew (GreenGuard Gold), claims to soak up formaldehyde. However, it contains a biocide which is likely not healthy.

It is a little harder to source than the ones above. In Canada you can find it at Lowes. Some have reported an odour 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.

Light Drywall 


USG SheetRock Ultralight
The major drywall companies all have lines that are lighter in weight, and these are very commonly used. We don’t know what is in 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.

Mold Resistant Drywall 


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

Fiberglass backed may be promoted as more mold resistant but it does not usually contain a mildewcide. It’s more mold resistant simply due to how it’s made.

Biocides are commonly used in the paper backed lines, if they are labeled as mold resistant.

 USG SheetRock Mold Tough line
Paper backed 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)
Greenboard in a generic term for green coloured drywall like these that have treated paper and are meant for areas with more moisture. It is still paper backed.

GP’s ToughRock Mold-Guard, American Gypsum’s Aquabloc and Sheetrock Mold Tough are greenboard.

Purple drywall by National Gypsum is similar to greenboard. It is paper backed and they claim it is treated for mold prevention.

Additional Health Concerns with Drywall


Greenboard


Use the Schulter system over backer board
It is not best practice to use greenboard (including purple) behind tiles that get wet. Best practice there is to use concrete backer boards with the Schluter system discussed in this post on bathrooms. If you want to create a mold preventative shower, Schulter is no question the best system.

Using greenboard 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


The “Chinese Drywall” debacle is the best known case of a major problem in the drywall industry. For a time (2001-2009) some drywall offgassed sulphur to the point of causing major problems. There have also been lawsuits against American made drywall, but they were dismissed (source). I have not seen any issues with sulphur 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 sulphur, 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 companies 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 


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 a N95 mask or better when around the dust. I use these masks all the time for many purposes.

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 only benefit to a Greenguard Gold product is it might catch these unusual problems with offgassing that have cropped up - either sulphur 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 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 0 VOC (the best ones), and in theory do not give off formaldehyde.

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

Joint Compound / Drywall Mud


There are many 0 or extremely low VOC drywall muds available at regular outlets.

Powdered drywall muds (spackle) are zero-VOC. USG Sheetrock Brand Lightweight Setting-Type Joint Compounds EASY SAND 20, as well as 30, 45, 90, 210, 300. Get a small amount on Amazon to test it out.

Proform drywall mud is extremely low VOC (considered "zero").

I used Murco as a joint compound, and found it totally tolerable. This one is marketed towards the chemically sensitive. So for those that want that extra reassurance, you could go with this brand.

The powder form is preferred to the pre-mixed. Even pre-mixed can be found in extremely low-VOC formulations, but it does offgas VOCs. The most sensitive should use the powdered form. Contractors prefer pre-mixed, so be sure to specify powdered mix.


For assistance with choosing the best wallboard for your needs, sensitivities, and budget, you can contact me for a one-on-one consult. 


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Sources:

1) https://www.buildinggreen.com/primer/synthetic-gypsum
2) https://www.thespruce.com/what-is-drywall-made-of-1821482
3) SDS sheets for all the major brands
4)http://www.teledyneleemanlabs.com/resource/Application%20Notes/AN1301%20Determination%20of%20Mercury%20in%20Synthetic%20Gypsum.pdf
5) www.ncbi.nlm.nih.gov/pubmed/19452875
6) https://www.researchgate.net/publication/298054499_Pre-contamination_of_new_gypsum_wallboard_with_potentially_harmful_fungal_species
7) http://www.freepatentsonline.com/y2011/0113961.html
8) https://www.thespruce.com/ultra-light-drywall-1821478
9) https://www.borax.com/BoraxCorp/media/Borax-Main/Resources/Brochures/borates-gypsum-board.pdf?ext=.pdf
10) https://www.propublica.org/article/american-made-drywall-emerges-as-potential-danger

5 comments:

Anaphylaxing said...

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

Corinne said...

that's good to know!

Anna said...

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

Corinne Segura said...

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

Anna said...

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.

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