Frequently Asked Questions about Wood Preservation

More Information

Click for more information on the topics below: Topical Publication Lists   o Acid copper chromate (ACC)   o Alkaline copper quat (ACQ)   o Ammoniacal copper citrate (CC)   o Copper azole (CBA-A or CA-B)   o Copper dimethyldithiocarbamate (CDDC)   o Environmental impacts of treated wood and methods to reduce the impacts   o Disposal and reuse of treated wood   o Natural durability   o Control of moisture in buildings   o Experimental preservative treatments   o Research methodologies in the field of wood preservation   o Effect of preservative treatment on mechanical properties   o Wood products production and consumption   o Field treatment Links to other sources   o American Wood-Preservers' Association (http://www.awpa.com/)   o Forintek Canada Corp./ Canadian Wood Council (http://www.durable- wood.com   o Southern Pine Council (http://www.southern pine.com/)   o Western Wood Preservers Institute (http://www.wwp institute.org/)   o U.S. Environmental Protection Agency (http://www.epa.gov/)   o US Forest Service, Forest Products Laboratory (http://www.fpl.fs.fed.us/)     FPL Publications   Recent FPL Publications are generally availabe from our Web site at http://www.fpl.fs.fed.us/ publications.html as PDF files. The most recent FPL publications are listed in "Dividends from Wood Research," FPL's semiannual listing of new publications. Sections of the listing relevant to wood preservation are "Durability" and "Decay Processes and Bioprocessing."   o Most recent issue   o Cumulative list (January 1996 to present) Two chapters of the Wood Handbook are particularly relevant:   o Wood Preservation, Chapter 14   o Biodeterioration of Wood, Chapter 13 Send comments to: Carol Clausen, Project Leader Wood Preservation US Forest Service, Forest Products Laboratory One Gifford Pinchot Drive Madison, WI 53726-2398 cclausen@fs.fed.us top of page

Q: How can I tell if my wood is properly treated?

To ensure that your wood is properly treated, look for a quality mark or stamp of an American Lumber Standards Committee (ALSC) accredited agency on the wood. If such a mark or end tag for the preservative treatment (not the lumber grade stamp) is present, it is an indication that the producer of the treated wood product subscribes to an independent inspection agency. These "third party" agencies verify for customers that their wood was properly treated in accordance with standards of the American Wood-Preservers' Association (AWPA). The used of treated wood with such third-party certification may be mandated by applicable building code regulations.

In addition to identifying information on the producer, the stamp indicates the type of preservative, the retention level of the preservatives, and the intended exposure conditions. Retention levels are provided in pounds of preservatives per cubic foot of wood. Retention levels are specific to the type of preservative, wood species, and intended exposure conditions. The appropriate treated wood will depend on whether the intended applications are above ground, ground contact, fresh water, marine (salt water), or in a permanent wood foundation. Detailed specifications on the different treatments can be found in the applicable standards of AWPA and ASTM International. The ASTM standard on specification for pressure treatment of timber products is ASTM D 1760.

If you are purchasing wood treated with a CCA, ask your supplier to certify that the chemical reactions, which occur within wood following treatment, have been completed prior to sale. These chemical reactions are what makes the preservative chemicals remain fixed within the wood during use.

For existing treated wood, there are ASTM and AWPA standards that provide information on methods for analysis and evaluation of treated wood and the preservative chemicals used.

Frequently Asked Questions

The first questions address new restrictions on the use of CCA-treated wood and the available alternatives. Then other frequently asked questions on wood preservation and related topics are also addressed. With few exceptions, references in this document were limited to publications of the Forest Products Laboratory. These answers are not intended to represent a complete review of the available literature.

1. What are CCA, ACA, ACZA, etc.?
2. Is it true that EPA has banned CCA-treated wood?
3. What are the alternative types of treated wood for residential use?
4. Has FPL evaluated these treated wood products?
5. Should I have concerns about existing CCA-treated wood?
6. How do I dispose of treated wood?
7. What about naturally durable species?
8. How can I extend the life of untreated wood?
9. Where can I find the climate index map of relative decay hazard?
10. What research is FPL doing on wood preservatives?
11. What experimental preservative treatments for wood has FPL investigated?
12. What test methods are used to evaluate new preservative treatments?
13. What is the impact of preservative treatments on mechanical properties of wood?
14. How can I tell if my wood is properly treated?
15. Where can I find additional information related to wood decks?
16. What is the market for treated wood?
17. Where can I find lumber treated for both flame retardancy and preservation?
18. Does FPL have any information on remedial or field treatment of wood?