Some Of The Most Frequently Asked Questions About Treated Lumber
ACQ Pressure-Treated Lumber
Answers to common questions about pressure-treated lumber.
ACQ Pressure-Treated Lumber; A Wood Preservation
Lumber's greatest enemy is biological attack ,destruction
by termites, fungi, marine borers and bacteria. After more than
a half century of scientific tests and practical experience with
various treating chemicals, there is a variety of weapons that
have been formulated to protect wood against insects, rot and
decay.
What preservatives are used and how
long are they effective?
What ingredients make up ACQ?
Is special handling required?
How safe is treated wood?
Can preserved wood be used indoors?
Why can treated wood be used for a picnic table
and not a countertop?
Can treated wood be used in gardening?
Can all tree species be treated?
What does PCF Treatment mean?
Any suggestions when building with treated
lumber?
After my project is built, is any special
maintenance necessary?
What else should I know about treated wood?
I cut the end off of my ACQ treated wood
and it looks like it isn't treated in the middle. Do I have a
bad piece of treated wood?
What preservatives are used
and how long are they effective?
For a long time, CCA (Chromated Copper Arsenate) has been used
as a reliable wood preservative. CCA treated wood protects against
all major forms of destructive attack and is effective for up to
50 years. More recently, preservative manufacturers have made a
transition to a newer preservative: ACQ (Alkaline Copper Quaternary.)
ACQ is also effective for up to 50 years, reducing demands on forest
resources.
What ingredients make up ACQ?
ACQ is a waterborne system that is copper-based. The copper and
quaternary compounds together provide protection from a broad spectrum
of fungi and termites, preventing rot and decay.
Is special handling required?
Although termites, fungus and destructive micro-organisms detest
treating chemicals, in pressure-treated wood it's clean, emits
NO fumes and is non-irritating.
The single most important precaution is DO NOT BURN TREATED WOOD.
Burning treated wood releases the chemical bond with wood cells,
so dispose of scraps and sawdust with your landfill trash. Wear
gloves when handling treated lumber. And always wear safety glasses
and a dust mask when sawing or cutting treated lumber just as you
would with untreated lumber.
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How safe is treated wood?
Very safe when used as directed. The preservative injected into
lumber reacts with the wood substance to form an insoluble complex.
It won't evaporate or vaporize. Treated wood is clean, odorless,
non-staining, and safe to work with and handle. Its locked-in protection
is non-irritating to children, adults, animals and plants.
The minute amounts of preservative released over time due to wear
off of the product or water contact have been carefully studied.
The conclusion is clear: it is safe for the environment and safe
for people and pets.
Can preserved wood be used indoors?
Treated wood may be used indoors for any application except cutting
boards and countertops.
Why can treated wood be used
for a picnic table and not a countertop?
Simply because picnic tables are primarily used for serving prepared
food while a kitchen countertop is used primarily as a cutting surface
for raw food.
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Can treated wood be used in
gardening?
Yes. Treated wood can be used to construct raised vegetable gardens and flowerbeds. Previously, CCA (Chromated Copper Arsenate) had been used as a reliable wood preservative. More recently, treated wood manufacturers have made a transition to a newer preservative: ACQ (Alkaline Copper Quaternary.) Several studies have shown that plants grown in CCA raised beds do not contain higher than normal levels of the preservative chemicals. It is believed also that the same holds true for ACQ raised beds. In addition, the components of ACQ are known to be non-carcinogenic.
Can all tree species be treated?
Three species of pine: southern yellow, ponderosa and red
are most open to treating. Some softwoods such as spruces,
hem/fir, larches and Douglas fir benefit from incising (cutting
small slits across the grain) to aid chemical penetration and treatment
retention. Most hardwoods are too dense and complex to be treatable.
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What does PCF Treatment
mean?
Treatment levels are measured in pounds of chemical injected per
cubic foot (pcf) of wood. Additionally, lumber tags will always state
above ground only (.25 retention) or ground contact
(.40 retention) so you can be sure you are using the right material
for the job. Higher levels of retention are available for special
purposes such as extensive moisture/earthen contact - e.g. in foundations,
pole barns, fresh & saltwater docks, culverts, etc.
Any suggestions when building
with treated lumber?
One quite important one: Use hot-dip galvanized (meeting ASTM-A153/A653) or (304 or 316) stainless steel
nails or screws, otherwise, your treated wood will last longer than
the unprotected fasteners you've used to put it together. Do not
use preserved wood in direct contact with aluminum. A poly barrier
is recommended for any applications where treated lumber will meet
aluminum flashing. Aside from that precaution, you can saw it, sand
it, or glue it just like any ordinary wood.
After my project is built,
is any special maintenance necessary?
Left unfinished, treated wood ages gracefully, eventually softening
to an attractive driftwood gray. On flat surfaces such as decks,
however, leaves and other debris may collect and create unsightly
stains. Even if your lumber has the locked-in protection of factory
applied water repellent, you'll want to follow an annual program that includes a semi-transparent
stain of a sealant which contains an ultraviolet stabilizer.
If you stain your project, a quality penetrating latex or oil base
stain is recommended.
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What else should I know about
treated wood?
Decades of research and testing have gone into its development,
and we certainly haven't answered every question about it.
However, a full line of free literature is available to you through
your building materials dealer. Finally, you should be aware of
this: lengthening a wood structure';s life through pressure
treatment lowers the pressure on our planet's exhaustible mineral
and energy resources. 226,000,000 trees are saved every year by
pressure treatment. Treated lumber makes one tree last as long as
many untreated trees. Use pressure-treated wood with confidence
in its everlasting quality and safety. You'll be protecting
our environment's major renewable building material.
I cut the end off of my ACQ
treated wood, and it looks like it isn't treated in the middle.
Do I have a bad piece of treated wood?
No. Products treated in strict
conformance with AWPA standards will have some wood which appears
untreated if the wood is end-cut after treatment. Most
commonly, this is heartwood which is naturally decay resistant.
This is not an indication that the wood was not properly treated,
and you do not need to be concerned. With the exception of some
Western species, these end-cuts do not require any special treatment.
Brush-on Preservatives for Field Cuts
According to American Wood-Preservers' Standard M4-02, lumber and
timber which are used in above ground applications and are of sapwood
species such as southern, red or ponderosa pine, generally do not
require treatment to provide a good service life. Other heartwood species, typically found in the Western
US, should be field treated when cut or drilled. If you are concerned
about wood exposed due to cutting or drilling, you can use a brush-applied
preservative. Home centers and lumberyards often carry brush-applied preservative
systems based on two different active chemicals: either copper naphthenate
or IPBC (3-iodo 2-propynyl butyl carbamate). These systems should
be applied, in accordance with their labels, to any surface exposed
by damage or field fabrication. Users should carefully read and
follow the instructions and precautions listed on the preservative
system label when using them.
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