Frequently Asked Questions
FAQs are divided into the following categories:
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AWPA Standards
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Treated Wood Uses
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Treated Wood Maintenance
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Miscellaneous
Is the use of AWPA Standards mandatory?
AWPA’s Standards are voluntary, so AWPA does not
mandate their use. However, AWPA Standards are almost universally used in specifying
treated wood products in the U.S. by architects, builders, the
construction and transportation industry, federal, state and local
agencies and others users and specifiers of treated wood.
Therefore, if these entities have specified AWPA Standards, then
they are made mandatory for those purposes and by those entities
with the authority to make them mandatory.
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What is the meaning of "C," "P," "M" and other
initials in the title of AWPA Standards?
AWPA’s Standards are designated by a letter, a
number and another number indicating the year the Standard was
adopted or most recently amended, such as:
For example, C2-99 indicates that it is the 1999
version of AWPA Commodity Standard C2 for the
pressure treatment of lumber and timber.
Other Commonly referenced Standards include:
| U |
Use Category System (Use category classifications
and specifications for users and specifiers of treated wood)
U1 User Specification for Treated Wood
|
| T |
Use Category System (Treatment and other
processing specifications for producers of treated wood)
T1 Processing and Treatment Standard
|
| P |
Preservative Standards (the composition of the
preservatives listed in AWPA Standards)
P1/P13 Creosote
P5 Waterborne Preservatives
P8 Oil Borne Preservatives
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| C |
Commodity Standards (the requirements for specific
wood products) Please note: The "C" Standards are no
longer being updated and will not be published after 2004.
These standards have been replaced by U1 and T1.
C3 Piles
C4 Poles
C9 Plywood
|
| N |
Nonpressure Standards (for the nonpressure
application of preservatives – brush, spray or dip)
|
| A |
Analytical Standards (standard methods for the
analysis of treated wood and wood preservatives)
|
| M |
Miscellaneous Standards
M4 Care of Preservative Treated Wood Products
|
| E |
Evaluation Standards (standard methods for the
evaluation of the efficacy of wood preservatives).
|
| F |
Conversion Factors and Correction Tables
|
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How can I get copies of outdated AWPA Standards?
Copies of all AWPA Standards from 1982 to present can be
purchased directly from the AWPA.
A few standards dated prior to 1982 are available as well. Please
contact us for
pricing and availability.
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What is the Use Category System?
The Use Category System (UCS) began as a format
revision of the Commodity "C" Standards and did not make substantive technical changes to those Standards. The UCS
contains definitions of the various Use Categories, a Service
Conditions section, a Treated Wood Use Selection Guide, a list of
AWPA accepted preservative systems, a Guide to Use Categories and
various Commodity Specifications relating to specific Product types such as sawn
products, utility poles, piling or fire retardant applications
The UCS became an official standard with the publication of the
1999 Book of Standards and should now be referenced instead of the C
Standards to specify products. Quality control and inspection
items are covered by the Analytical (A) and Miscellaneous (M)
Standards.
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What do LP-2 and LP-22 mean?
"LP-2" and "LP-22" were
Inspection Procedures which had been used by the American Wood
Preservers Bureau (AWPB) to determine the conformance of
preservative treated wood products to certain Standards of the
American Wood Protection Association (AWPA). AWPB ceased to exist on
December 31, 1993.
"AWPB LP-2" had often been used as a "shorthand"
method of describing lumber and plywood which had been preservative
treated with then-current waterborne preservatives to a retention of 0.25 pounds
per cubic foot intended for above ground use. In a similar fashion "AWPB
LP-22" had often been used to describe lumber and plywood treated
with waterborne preservatives existing at that time to a retention of 0.40 pounds per
cubic foot intended for soil and ground contact use.
To use
current AWPA Standards to specify the above described material the
specifier should call out AWPA Standard U1 and T1. These UCS
Standards should be consulted to determine the species,
preservative, and retention level combination which will provide
similar protection to the finished product.
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How can I get wood tested to see if it has been
pressure treated and to determine the amount of preservative in the
wood?
AWPA’s Analytical Standards include several standard
methods for detecting the presence and amount of preservative
elements in wood.
Several of the treated wood inspection companies can
also inspect the wood, take the necessary samples and run the
analytical procedures to determine if the wood has been treated and
the remaining level of preservative in the wood.
Some of the companies are sponsors of AWPA and can
be located by going to our
"Suppliers and Sources" page.
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How long will treated wood last?
AWPA cannot predict the expected life of specific
pieces of treated wood.
You could contact the preservative
manufacturers listed on our
"Suppliers and Sources" page for product literature on the anticipated
performance of wood products treated with their formulations in the
specific application you have in mind.
You might also want to read
USDA
Forest Service Research Note 02 on over 60 years of field stake
tests.
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Where can I get information on the health, safety,
and environmental aspects of CCA treated wood?
The
Wood
Preservative Science Council has a website which contains a
great deal of information on the science, epidemiology, risk
assessment and toxicology of CCA treated wood.
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Has Creosote been banned?
Creosote continues to be registered by the
Environmental Protection Agency as a wood preservative. It is the
second most widely used wood preservative in the U.S. It is used
primarily for treatment of industrial products such as railway ties, utility poles, and
piling.
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Does CCA preservative leach from wood in service?
There are several sources that might have the
information you are seeking: the companies that manufacture the
CCA preservative,
Arch
Wood Protection,
Chemical
Specialties Inc., and
Osmose
Inc., as well as the
Western Wood Preservers
Institute. You might also contact
Dr. Paul Cooper for
information on his studies in this area. Another source of
information is the review on Leaching of Preservatives by Dr. Stan
Lebow found at
US
Forest Service GTR 93.
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What is the leaching rate for chemicals from a 2.5
pcf CCA treated piling into a marine environment?
The
Western Wood
Preservers Institute has developed models on the movement of
wood preservatives from piling into marine environments. One
scientist who has done extensive work on the use of preservative
treated wood in the marine environment is Dr. Kenn Brooks, you may
contact him through the WWPI. Further
information can be found in a
USDA Forest Service study on preservative leaching in the
marine environment.
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Can wood be preservative treated and fire retardant
treated at the same time?
For product and performance information, please
contact the manufacturers of fire retardant chemicals as listed on
our "Suppliers and Sources" page.
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Does material that is fire retardant treated in
accordance with AWPA Standards C20 (lumber) and C27 (plywood) meet code
requirements for Class I, for a one-hour wall or for a two-hour wall?
For product and performance information, please
contact the manufacturers of fire retardant chemicals as listed on
our "Suppliers and Sources" page.
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Can I glue other materials (carpeting, plastic
overlays, other wood) to pressure treated wood or to fire retardant
treated wood?
For technical information on the glue performance
of treated wood and fire retardant treated wood please contact the
preservative or fire retardant chemical manufacturers listed on
our "Suppliers and Sources" page.
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How many utility poles are there in the United
States?
The most recent information we have available regarding the
number of utility poles (communications and power transmission and distribution) in the
U.S. is around 134 million. Of these, 51 million are with
Investor-owned Utilities, 37 million with Rural Electrical
Associations, 38 million with telephone companies, and 8 million
are owned by railroads. There are also some 195 crossarms in
service in the U.S. In 1997, approximately 64.5 million cubic
feet of poles were pressure treated.
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How much wood is pressure treated in the United
States?
In 1997 approximately 727.8 million cubic feet
(20.6 million cubic meters) of wood products were pressure treated
in the United States.
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What marks should be present on treated wood
products?
Usually there are two sets of
marks on lumber and plywood that has been pressure treated.
The first set of marks pertain
to the "white wood" (the untreated product). These usually will
include the company that manufactured the untreated product (often
"Mill No. XXX") the species of wood, the grade or strength value
of the wood, and the logo of the inspection agency.
The second set of marks are made by the treating company
and will
either be stamped on the wood or on an end tag stapled into the edge
of the wood. This mark should include the name of the treating company, the
year in which the wood was treated, the preservative used, the
level of treatment (0.10, 0.25, 0.40, etc.), the intended use (above
ground, ground contact, etc.) a reference to the appropriate AWPA
Standard, and the logo of the inspection agency.
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Does wood preservation protect against moths?
No. The purpose of wood preservation is to deter
insects and fungi. Moth control is usually attributed to aromatic
woods such as cedar.
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Which is better to use for my treated deck?
ACZA, Copper Azole or
ACQ?
All of these preservatives (and a few others) are
included in AWPA's Standards for sawn materials used in above
ground applications. For product information, please contact
the manufacturers of wood preservative chemicals or treated lumber
as listed on our "Suppliers and
Sources" page.
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How should I treat cut surfaces of treated wood?
AWPA Standard M4 recommends treating any cut,
bored, drilled or adzed surfaces of treated wood with a
preservative solution. The most commonly available preservative
meeting the requirements of Standard M4 is a Copper Naphthenate
solution containing at least 2% copper. Allow the preservative
to soak in before applying the next coat.
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What labels should I look for in buying Copper
Naphthenate (because my hardware store doesn't know what I am asking
for)?
The 2% (metal) products are currently available
under the following brand names.
Behr #90 Dock and Post Preservative
WM Barr Kleen Strip Coppo-W Exterior
Wood Preservative
Green's CopperGreen
Jasco Termin-8
Cuprinol Green #10
Waterborne versions are available also. Brand names
are as indicated below:
Dap Below Ground Wood Preservative
Henry Shakeguard (cedar color added)
Henry Greenguard (standard green tint)
Fields ATCO Shakelast (cedar color
added)
Fields ATCO Woodlast (standard green
tint)
Dap products are available nationwide as are WM
Barr Kleen Strip, Cuprinol and Behr products. Green's, Jasco,
Henry and Fields are primarily in West Coast distribution.
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The builder did not use pressure treated wood in
locations required by the Building Code. What preservatives can I
now apply to have the wood comply with the AWPA Standards?
The AWPA Standards, with minor
exceptions, addresses the pressure impregnation of wood products with
specific wood preservatives. This is done at pressure treating
plants before the wood products move to the job site. The
exceptions are for the treatment of cut surfaces in already
treated wood products of for the treatment of millwork also at the
manufacturing site.
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What should I do to maintain my treated wood deck?
Information should be available at your local
hardware or building supply store in the form of product brochures
or how-to-do-it books. Also, you may wish to check out the
following USDA Forest Products Laboratory publications:
How to Finish Wood Decks
Cleaners for Wood Decks
Refinishing of CCA-treated wood
Additional information on maintenance and painting
of treated wood is available from the three companies which
manufacture waterborne wood preservatives. Links to these
companies can be found on our
"Suppliers and Sources" page.
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What is the procedure for having a new wood
preservative listed in the AWPA Standards?
This can be a rather involved
process, but not an insurmountable one.
Manufacturers of wood preservatives must be able to
verify the current registration of their product with the U.S. EPA.
While products with pending EPA registrations are eligible to be
proposed for AWPA Standards, final approval and publication as a
Standard will not occur until EPA registration is complete, and only
for the EPA approved uses.
The procedure for developing and presenting the
necessary technical information for consideration for inclusion in
AWPA’s Preservatives Standards is described in
Appendix
A (PDF File) to the
AWPA Technical Committee Regulations.
The similar procedure for including fire retardant
formulations in AWPA’s Standards is described in
Appendix
B (PDF File) to these
Regulations.
For further information, contact
the AWPA.
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How do I find out about expected species
characteristics, physical properties or treatability and durability?
The USDA, U.S. Forest Service, Forest Products
Laboratory in Madison WI has complied an extensive set of
Technical Data Sheets on over 200 North American species and over
500 tropical species.
Use
this link to get information common and scientific names,
physical and mechanical properties, durability, treatability,
working characteristics, and common uses for the particular wood
species you are interested in.
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What companies manufacture or distribute
preservatives listed in the AWPA Standards and how can I get
information on particular wood preservatives?
There are many manufacturers and distributors of
wood preservatives, some of which are unknown to the AWPA.
Links to several companies that make or distribute wood
preservatives or fire retardants are listed on our
"Suppliers and Sources" page.
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