Chemical Offgassing from Pressed Wood and Laminated Wood Products

A Guide to Choosing Pressed, Engineered and Laminated Wood Products – Their Formaldehyde and VOC Levels

This post will cover pressed wood and laminated wood (engineered wood) products used in building, and in household items like furniture and doors.

We are going to look at formaldehyde and other adhesives used and what do they offgas. I will also note which wood types are commonly used.

This is going to be the adhesives used in the US and Canada. Europe will be similar. Other parts of the world may use different adhesives.

This post contains affiliate links to relevant products that I use and recommend. Upon purchase, I earn a small commission at no extra cost to you.

Adhesives used in Engineered Wood Products 

MDI methylene diphenyl diisocyanate – offgasses methylene diphenyl diisocyanate, though the companies claim this cures into a polyurethane.

PF Phenol-Formaldehyde – The change to CARB 2 regulations forced most furniture/cabinet companies to move to phenol-formaldehyde. The offgassing is much lower and in many products comes to a complete cure in a short amount of time.

UF Urea Formaldehyde – 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 of urea-formaldehyde. Try and avoid this type.

NAUF No added Urea Formaldehyde, essentially means PF is used.

NAF No added formaldehyde, this means no formaldehyde is added to the product. They cannot be called formaldehyde-free because wood naturally contains formaldehyde. No added formaldehyde products are often made with MDI or “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 coinventor 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 a amine-epichlorohydrin adductt/soy protein/isocyanate (source).

Product Certification Formaldehyde Levels:

CARB II – Formaldehyde Levels

CARB II is a standard set by California for products sold there, but most building products across North America comply with this requirement.

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

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

CARB II Formaldehyde Limits are:

E-0 E-1 and E-2 European Formaldehyde Levels 

E1 certifies that boards release less than 0.1 ppm (parts per million) and for E2 boards 0.1 ppm and 0.3 ppm. E0 is 0.07 ppm

GreenGuard and GreenGuard Gold Formaldehyde Levels

GreenGuard 0.05 ppm (parts per million) formaldehyde and GreenGuard Gold 0.0073 ppm formaldehyde.

How Much Formaldehyde is Acceptable for those Avoiding Toxins?

How do you interpret these levels

Formaldehyde is naturally occurring in wood, plants, animals (including humans), and therefore in the outside air as well.

In fact, wood has a level of natural formaldehyde high enough that if you made a house completely out of wood, you could go over some recommended indoor formaldehyde levels.

Formaldehyde is also produced by human industries, adding to the natural levels in outdoor air everywhere.

The major sources in urban air are power plants, manufacturing facilities, incinerators, and automobile exhaust emissions. Source

Formaldehyde Reference Levels

Wood Products & Adhesives

Plywood (Interior and Exterior)

Which Chemicals does it Offgas?

Exterior plywood

Exterior grades of plywood are used for roof sheathing, subfloors and roof decking.

Exterior grades of plywood is made with phenol-formaldehyde as the binder/glue. Phenol formaldehyde is the least toxic type as it offgasses less and it ofgasses faster.

Exterior plywood can also be called structural plywood or softwood plywood (SWPW).

Type of wood:

It is made of softwood, usually fir (or spruce, pine). In Canada, Douglas Fir Plywood (DFP) (can have up to 21 other species of woods in the inner plies), and Canadian softwood plywood (CSP) may have balsam poplar, trembling aspen and cottonwood.

Formaldehyde:

When the American Plywood Association (APA) tested formaldehyde levels of new exterior plywood they started 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 is was not possible to measure them accurately” source APA.

While the APA would not say exactly when the PF levels approached 0 or close to it, this is the study that changed my thinking on avoiding plywood in a new build.

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 generally prefer plywood. My post on sheathing goes into more detail on alternatives if you need to avoid both plywood and OSB.

CDX plywood

CDX is a type/grade of exterior plywood used for sheathing with an Exposure level of 1 other types ending in X are also made for the exterior.

Marine-grade plywood

In the US the marine-grade plywood I’ve seen contains PF, but they can use other glues as well. This is not a specific type of plywood in Canada.

Grades of Plywood

These are grades of Plywood in the US. And here are grades of plywood in Canada.

Pressure-Treated Plywood

Pressure-treated plywood is commonly is treated with Alkaline copper quaternary (ie 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 not commonly used in residential buildings.

Interior Plywood

Interior grades of plywood were often is made with urea-formaldehyde as the adhesive. Urea-formaldehyde (UF) offgasses more and for longer.

Now, phenol-formaldehyde (PF) is more standard. Interior plywood is often called furniture grade or hardwood plywood. You will want to make sure your furniture is made with PF not UF or with NAF glues.

Interior plywood is made of hardwoods (usually) of various types, though it can be made of softwood like cedar.

Purebond no Added Formaldehyde Plywood – Purebond Plywood is widely known as the healthier alternative to interior grade plywood.

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

Their adhesive is partially proprietary, but they claim it is “soy-based”. The full Declare label is here but this doesn’t say much about what it will offgas.

I have seen chemically sensitive folks react to this brand of plywood so I would make sure to test it out yourself before using.

Purebond plywood is “interior grade”, it is not structural and it is not made to hold up to high humidity or moisture.

Folks are using this improperly when using it as sheathing and roof decking.

For those less sensitive Purebond is a good choice for furniture and cabinets. You can find it as a component of many preferred kitchen cabinets companies here. You can buy it at Home Depot and Amazon.

Medium Density Fiberboard (MDF)

Which Chemicals does it Offgas?

MDF is often made with urea-formaldehyde which offgasses more than phenol.

Where it’s used:

You will find MDF in cabinets, solid-core and hollow core doors, furniture, and as part of some flooring.

My posts on kitchen cabinets, furniture, doors, and flooring provide alternatives.

MDF is also used in baseboards and other trim which can easily be swapped out for solid wood.

Glues and offgassing:

There are brands of no added formaldehyde MDF that may be used by some specialty furniture makers, but it is not what you will commonly see.

One brand is GP Ultrastock FR, the glues are MDI and another isocyanate. Roseburg also makes a number brands: Arreis, Medex, Medite, Permacore, and Fiberlite.

In most MDF the level of formaldehyde offgassing are higher in MDF than in plywood, even if both are CARB 2 certified – 0.11 ppm in MDF compared to 0.05 ppm for plywood.

MDF made with formaldehyde should be avoided where possible in a healthy home.

Oriented Strand Board (OSB)

Which Chemicals does it Offgas?

OSB is usually made using phenol-formaldehyde (PF) and MDI as the adhesive (MDI primarily in OSB though they claim the MDI fully cures into a polyurethane). MDI offgases isocyanates.

Where is it used:

OSB is often used in house sheathing – roof sheathing/decking, exterior sheathing and in floors (subfloors).

Usually, OSB or plywood can use used interchangeably for the same application in a building.

Sensitive folks usually choose plywood over OSB, but some brands of OSB listed below can be very good.

Wood types:

OSB is made from either hardwoods or softwoods. The most commonly used softwoods for manufacturing OSB are pines/firs/spruce. Aspen is the most commonly used hardwood.

In the US look for APA OSB which will not contain UF.

There is no added formaldehyde (“formaldehye-free”) OSB, but they may be harder to source.

Particleboard/Low-Density Fiberboard (LDF)

Which Chemicals does it Offgas?

Urea-formaldehyde (UF) (the type that offgasses more and for longer) is usually used as the adhesive in particleboard. You may also see MDI used.

Where is it used:

Particleboard can be used in cabinets and in some inexpensive furniture.

For safer options, see my posts on healthy kitchens and healthy furniture.

High-Density Fiberboard (HDF)

Which Chemicals does it Offgas?

Hardboard/HDF/fiberboards could be made with either phenol-formaldehyde (which offgasses fairly quickly), asphalt or no adhesive, depending on type.

Paraffin wax and a small amount of ammonia are typical. Linseed can be added to some types.

HDF is used in the substrate of many floorings like Marmoleum Click and almost all laminates.

It is also used to made Masonite and other brand hollow core doors (as the skin).

It’s often found as the backing to furniture, like dressers and bookcases.

Pegboard is made from HDF.

Structural Engineered Beams and which Chemicals they Offgas

• Glulam, PSL, LVL are usually made with phenol-formaldehyde (PF).
• PF is also used for finger joining stress graded lumber.
• TGI beams are made with PF and MDI glues.
• Cross-laminated timber can be made with a variety of different glues: polyurethane, isocyanate (EPI), melamine, or phenolic adhesives. The most common adhesives are formaldehyde-free – polyurethane or EPI. With polyurethane being the most common.
• LSL is mainly made with the adhesive MDI and I have seen a small percentage of undisclosed binders.
• i beams are made of steel

To avoid laminated wood beams you will have to consider that decision in the very initial planning and design of your house. See this post on considerations that need to be made early in the build for the chemically sensitive.

Chemical Adhesives by Brand

Brands of Plywood and OSB and which Chemicals they use as Glues

• Norbond Trubond – PF and MDI
• Aventech Roof OSB – PF and MDI
• Avantech Subfloor – PF and MDi (claims to be lower-emitting that typical OSB)
• Ultrastock MDF – UF
• Medex and Medite II by Roseburg – No formaldehyde MDF
• Purebond Plywood – no added formaldehyde, proprietary glue used
• Roseburg – only lists PF as glue
• Zip Systems – Phenol formaldehyde and MDI
• Georgia Pacific DryGaurd (what glue?) claim to be lower-emitting than typical OSB.

Cost comparison of OSB, plywood and Avantech Sheathing.

Corinne Segura is a Building Biologist with 6 years of experience helping others create healthy homes.

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Additional Sources:

https://www3.epa.gov/ttn/chief/ap42/ch10/final/c10s06-1.pdf

http://wooddesign.dgtlpub.com/2013/2013-03-31/pdf/Technical_Solutions.pdf