Is solid wood T-111 safe for interior use?

Asked by Cristina
Miami, FL

Our cabin in GA has T-111 on the walls. My son, my husband and I get horrible allergies, sinus infections, and more recently bronchitis with a visit to the ER. I was reading about T-111 and the use of Formaldahyde. Could our cabin be making us sick? What testing can be done to determine the cause of our allergies? I believe it's the T-111. My husband is in denial and thinks the allergies are seasonal. However, we go outside and miraculously our allergies go away. Please Help!


Could your cabin containing T1-11 make you sick--absolutely. Could it be something else such as a finish used or a sealer--absolutely. 

You have to isolate the products to be sure which is causing the issues and that can be challenging, especially after it has been installed.

People react to chemicals in different ways; those that are sensitive can smell tiny amounts of chemical emissions. Others can't smell the strongest of odors.

Handling the chemical odors

Chemical sensitivity has been a growing problem in our polluted society and taking it seriously, sooner rather than later, helps avoid long terms health problems.

Adding ventilation, fans or heat to the paneling will accelerate off-gassing but it may continue for months or even years.

A better approach, that we have found successful, is to seal in the chemicals so they can't escape. AFM Safecoat makes a product called Safeseal or HardSeal that immediately blocks toxic fumes coming off the wood.

  • It works by encapsulating the surface permanently.
  • It's easy to use by anyone with a roller or sprayer and is very effective.

MSDS is of limited use

If you look at the Material Safety Data Sheet, (MSDS) for T1-11 Textured Plywood
Siding on Georgia Pacific's website (here) you'll find that they don't provide a specific MSDS sheet for this product but group them with all their other wood products.

This makes it nearly impossible to determine just what chemicals are contained in T1-11.

  • They claim that the wood in these products including T1-11 "may be sprayed with sap stain control coatings" but don't say what the coatings contain.
  • They claim that "No chemical residue is left on the surface of the board. Wood products are bonded with phenol, phenol resorcinol, melamine formaldehyde-based, or polyvinyl acetate resin. Some wood products may be coated with finishes, sealants and or overlays."
  • Such descriptions are vague and focus your attention on wood dust instead of chemical off-gassing.
  • They do state that under section 311 it does contain hazardous chemicals, but what type and how much is not divulged.

MSDS sheets, which are publicly available, are voluntarily created by the manufacturer to help consumers and mainly contractors understand how to deal with safety issues such as dust, fire, transportation and disposal. There is no oversight by any public or private organization to verify that this information is accurate or up to date. Proprietary information such as trade secret ingredients are not required by law to be listed. Also, anything less than 1% does not have to be listed either.

Effects unknown

Furthermore, manufacturers are not required to list toxic ingredients unless they
are "known hazards"
listed on the EPA's database. This list started in the late 1970's by the US Government Toxic Substance Control Act (TSCA) contains all the hazards considered toxic to humans by consensus.

  • Unfortunately, there are thousands of chemicals that have never been tested for their effects on humans nor could anyone possibly test the synergistic effects caused by combining chemicals in various ways.
  • As a result we have a very short list of volatile organic compounds (VOCs) that is primarily concerned with potential harm to the outdoor environment, i.e. smog.
  • Acetone and ammonia are examples of hazardous chemicals that are not regulated by OSHA because they don't cause outdoor air pollution.

There may be many other new chemicals sourced from overseas that no one even knows about, yet they find there way into building materials here in the USA.

Ask lots of questions

Learning about chemicals is a serious research project made easier by the internet.

  • Here is more info that may help you. 
  • Manufacturers are not very transparent about what’s contained inside their products. 

Ultimately, you can't trust anyone and you have to rely on your own testing and become your own scientist. I realize this may not be what you intended when you purchased some T1-11 but healthy living requires a pioneering spirit and a willingness to ask lots of questions and continual testing in pursuit of the truth.

If you have further questions, please feel free to call or email.


Joel Hirshberg
[email protected]


For more information:

Read "Is there a finish I can use to seal MDF surfaces on a changing table for my baby’s nursery?" a Q&A answered by Debbie Sek.

Also, read "Can I install Hardiplank siding over T111?" a Q&A answered by Nichoel Farris.

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