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Frequently Asked Questions

Does California set limits on formaldehyde emissions?

California’s Air Resources Board (CARB), a division of the California EPA, is working to enact new regulations to reduce formaldehyde emissions from wood panels and products made from wood panels used in the state. The new regulations will establish the most stringent formaldehyde emission limits on wood products in the United States. The measure requires that wood panels and products manufactured from wood panels be certified by a “third party” laboratory approved by the CARB as meeting California’s emissions requirements. Panel manufacturers, importers, distributors, fabricators and installers can all be held responsible for assuring that their products comply. The new emissions limits are scheduled to be phased in starting 2009 and fully implemented in 2012.
Click here to read the entire regulation order.

Click here to download a Composite Panel Association Fact Sheet on the new California regulation.

Because structural wood products certified by APA under U.S. Voluntary Product Standards PS 1 and PS 2 are manufactured with moisture resistant adhesives that emit formaldehyde at very low levels well below the CARB limits, the wood panels are exempt from the CARB regulations.

Do formaldehyde emission regulations apply to Murphy APA rated panels?

Manufactured to North American product standards, Murphy APA rated panels are exempt from the world’s leading formaldehyde emission standards and regulations due to their very low emission rates.

APA rated wood structural panels – including plywood and oriented strand board (OSB) — are manufactured to meet stringent product standards, like Voluntary Product Standard PS 1-09 – Structural Plywood and Voluntary Product Standard PS 2-10 – Performance Standard for Wood-Based Structural-Use Panels. Because wood products manufactured under these standards are designed for construction applications governed by building codes, they are manufactured only with moisture-resistant adhesives that meet Exterior or Exposure 1 bond classifications. These adhesives, typically phenol formaldehyde and polymeric diphenylmethane diisocyanate (pMDI), are chemically reacted into stable bonds during pressing. The final products have such low formaldehyde emission levels that they easily meet or are exempt from leading formaldehyde emission standards and regulations, including the U.S. HUD Manufactured Housing Standard, the California Air Resources Board (CARB) Air Toxic Control Measure for Composite Wood Products, and the Japanese Agricultural Standards (JAS).

Learn more about formaldehyde and wood products.


How much formaldehyde is in wood?

Formaldehyde is an organic compound found naturally in wood and a wide range of foods, including fruit, vegetables, mushrooms and seafood. It is also a normal product of human metabolism. Because formaldehyde occurs naturally in wood, there is no such thing as “formaldehyde-free” wood.

As with most environmental exposure risks, the issue is not with the chemical itself but with unusually excessive or immoderate exposure levels. APA rated panels are exempt from the world’s leading formaldehyde emission standards and regulations due to their very low emission rates.

Learn more about formaldehyde and wood products.

Is manufacturing wood panels energy efficient?

Processing wood into usable products, such as plywood and OSB panels, is highly energy efficient. Wood products make up 47 percent of all industrial raw materials manufactured in the United States, yet consume only 4 percent of the energy needed to manufacture all industrial raw materials, according to a 1987 study. Compared to wood, it takes five times more energy to produce the same amount of cement, 14 times more for glass, 24 times more for steel and 40 times more for aluminum.

Waste utilization and bioenergy go hand in hand. Over one half of the energy needed for wood production comes from tree bark, sawdust and other natural by-products. The U.S. and Canadian wood products industries are leaders in bioenergy use. In fact, the U.S. wood products industry alone accounts for 60 percent of the nation’s bioenergy production and use.

Learn more about the environmental benefits of sourcing wood products.

Are we running out of trees?

No – the United States forestland is roughly as abundant now as it was 100 years ago. According to the USDA Forest Service, there are 750 million acres of forestland in the U.S. today, about the same as in 1907. And through the efforts of our forest industries, our forests are continuing to expand: 27 percent more timber is grown than harvested from our sustainably managed forests every year.

North American managed forests comply with one or more certification agencies responsible for verifying proper forestry practices. These practices include following applicable laws, protecting wildlife, providing habitat buffers, and ensuring waste reduction and reuse. Learn more about forest management certification and view the certification status of Performance Panel manufactures.

Learn more about the environmental benefits of sourcing wood products.

Quality Ratings

Why are Murphy APA rated panels superior to imported panels?

Murphy APA rated “Performance Panels” are manufactured to stringent product standards (such asVoluntary Product Standard PS 1-09 – Structural Plywood and Voluntary Product Standard PS 2-10 – Performance Standard for Wood-Based Structural-Use  Panels) and under the most rigorous, state-of-the-art quality assurance programs in North America, the APA quality services programs.

Many imported panels never undergo product qualification testing. Without such tests it is impossible to determine how the panel will perform for the intended use. As an internationally accredited testing laboratory, APA put imported hardwood plywood panels from China and Brazil up against domestic plywood certified to PS 1. As expected, theimport test results indicated inferior mechanical and connection properties, severe failure for bond durability, and only one tested sample would have met the formaldehyde limits imposed by CARB when compared to APA rated plywood.

Look for engineered wood panels bearing the APA trademark. It appears only on North American products manufactured by APA members committed to APA’s rigorous program of quality inspection and testing.

Learn more about the Performance Panels performance standards.

What is the difference between Exterior and Exposure 1?

Exterior panels are suitable for applications subject to long-term exposure to weather or moisture.

Exposure 1 panels may be used for applications where construction delays may be expected prior to providing protection. Exposure 1 panels are made with the same exterior adhesives used in Exterior panels. However, because other compositional factors may affect bond performance, only Exterior panels should be used for long-term exposure to weather.

Note: APA Rated Plywood Sheathing Exposure 1, commonly called “CDX” in the trade, is sometimes mistaken as an Exterior panel and erroneously used in applications for which it does not possess the required resistance to weather. “CDX” should only be used for applications as outlined under Exposure 1 above. For sheathing grade panels that will be exposed long-term to weather, specify APA Rated Sheathing Exterior (C-C Exterior plywood under PS 1).

For more information, please refer to Technical Topics: Bond Classification, Form TT-009, available for free PDF download from the APA Publications Library.

What is the difference between Structural I and Exposure 1?

It is important to understand that the term Structural I refers to certain specialized strength and stiffness characteristics of wood structural panels while the term Exposure 1 refers to the glue bond durability of a wood structural panel.

What do the numbers and letters on the Murphy - APA trademark represent?

APA trademark is Murphy Softwood Plywood assurance that the product conforms to manufacturing and product performance standards shown on the trademark. The mark appears only on products manufactured by APA members committed to APA’s rigorous program of quality inspection and testing.

APA trademark is Murphy Softwood Plywood assurance that the product conforms to manufacturing and product performance standards shown on the trademark. The mark appears only on products manufactured by APA members committed to APA’s rigorous program of quality inspection and testing.

We’re often asked "What do all those numbers and letters on the grade stamp represent?" The answer usually depends on the panel specified and its final application. Here are three examples of the APA trademark that you may find on APA rated structural panels.


Download the APA Trademarks & Grade Stamp Anatomy PDF for detailed line-item definitions of what is included in the trademark.

Don’t be alarmed if the stamps on your panels don’t contain all of the information shown above; the trademark information on a particular panel depends on its end-use, among other factors.  At a minimum, however, you should see the product or veneer grades, mill number, product standard governing manufacture and bond classification.

If you have any questions about the information contained within an APA trademark, please contact us.

Do mold and mildew compromise the integrity of engineered wood?

Mold and mildew are microscopic fungi, a low form of plant life that lives off of organic matter rather than a photosynthetic process. Mold and mildew appear as woolly or powdery growth on numerous substrates. Mold spores are always present in outdoor and indoor air, and almost all building surfaces can provide nutrients to support growth. The incidence and development of mold and mildew depend heavily on temperature and moisture conditions. A warm, wet or humid environment provides ideal conditions for the development of mold and mildew on a variety of surfaces, including wood structural panels.

Mold and mildew are terms commonly used interchangeably, although mold is often applied to black, blue, green, and red fungal growths, and mildew to whitish growths. The color depends on the infecting organism and the type and moisture condition of the nutrient. For example, white mold is commonly found on water-saturated laboratory test samples of wood stored at room temperatures overnight.

Mold and mildew are not decay-producing fungi, although decay may occur under similar conditions as mold and mildew (high moisture, 30% ± moisture content). By itself, the water vapor in humid air usually will not wet wood sufficiently to support significant decay, but it will permit development of some mold and mildew fungi. Thus, wood will not decay if it is kept air dry.

Allowing the wood to dry to a moisture content not exceeding 20% stops further growth of mold or mildew fungi. The surface growth often can be easily brushed or surfaced off. Additionally, a chemical spray solution of 10% household bleach and water will kill the fungi. However, under renewed moist conditions, new infestation may occur.

For additional information refer to APA’s Mold and Mildew publication and, which includes a ten-point mold protection plan and links to related online information.