Information for Pressure-Treated Lumber

Lumber’s greatest enemy is biological attack, which would be destruction by termites, fungi, marine borers and bacteria.  After more than half a century of scientific tests and practical experience with various treating chemicals, there are a variety of weapons that have been formulated to protect wood against insects, rot and decay.  This is why it is a good idea to use pressure-treated lumber.

            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 many years.  More recently, preservative manufacturers made a transition to a newer preservative, ACQ (Alkaline Copper Quaternary.)  ACQ is also effective for decades, reducing demands on forest resources.  The next generation of preserved wood is ProWood Micro, a revolutionary product being offered throughout the United States by Universal Forest Products.

            ProWood Micro 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.

            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 goggles and a dust mask when sawing or cutting treated lumber just as you would with untreated lumber.

            Treated wood is 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, safe to work with and handle.  Its locked-in protection is nonirritating to children, adults, animals and plants.  The minute amounts of preservative released during a treated wood structure’s serviceable lifetime have been carefully studied.  The conclusion is clear: it is safe for the environment and safe for people and pets.  Treated wood may be used indoors for any application except cutting boards and countertops.

            Treated wood can be used in gardening.  Treated timbers used to construct raised vegetable and flowerbeds are increasingly popular and practical.  Recent scientific tests prove there is no significant uptake of preservatives into plants.  And treated wood used for tomato stakes, flowerbed edging, planters, retaining walls, trellises, and compost bins have the added advantage of lifetime durability.

            There are different types of treated wood for different uses.  The tags will always state “above ground only” or “ground contact” so you can be sure you are using the right material for the job.  Higher levels of preservative are available for special purposes such as extensive moisture/ earthen contact – e.g., in foundations, pole barns, fresh & saltwater docks, culverts, etc.  Use hot-tip galvanized fasteners or other fasteners as required by building codes; otherwise, your treated wood will last longer than the unprotected fasteners you’ve used to put it together.  Since ProWood Micro is less corrosive than ACQ, these recommendations are the same as they were with CCA-treated lumber.  Fastener manufacturers may also recommend products that work well with ProWood Micro.  Aluminum building products can be placed in direct contact with ProWood Micro treated wood products used for interior uses and above ground exterior applications such as decks, fencing, and landscaping projects.  Examples of aluminum products include siding, roofing, gutters, door and window trim, flashing, nails, fasteners and other hardware connectors.  Aluminum contact is not recommended when ProWood Micro treated wood products are immersed in water or are subject to frequent and prolonged wetting or other severe exposure conditions.  In such cases, a moisture resistant protective barrier should be placed between the aluminum products and ProWood Micro treated wood.

            If you cut the end off of your pressure-treated wood, and it looks like it isn’t treated in the middle, it’s not just a bad piece of treated wood.  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 M4-06, 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.  This category includes the majority of the treated products Universal Forest Products provides.  Other heartwood species, typically found in the Western U.S., 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 of field fabrication.  Users should carefully read and follow the instructions and precautions listed on the preservative system label when using them.