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Southern Yellow Pine




What is pressure treatment?

Pressure treatment is a carefully controlled process of pressure and vacuum cycles within an enclosed cylinder. The process forces preservatives deep into the cellular structure of the wood, forming a chemical bond that resists decay and attack by insects. This bonding process, known as “fixation,” locks the preservative into the wood, making it highly resistant to leaching or dissolving.

What preservatives are used?

The most commonly used preservatives for treating lumber for residential use are MCA, CCA, and Borate. Over a million decks and countless other outdoor structures are built each year using Southern Pine lumber that has been treated with these preservatives.

Is MCA (micronized copper azole) treated Southern Pine safe?

Perfectly safe. You can play barefoot on it, build garden beds out of it, lie out in the sun on it, or eat a picnic on it. Treated lumber is a nontoxic product that only frustrates termites and fungus. Like many chemical substances that require special handling, these preservatives have regulations for use established by the EPA. It can only be sold to certified wood treatment facilities. The EPA’s regulations apply only to the chemicals, not to the finished product. Once these preservatives are locked into the wood, they are perfectly safe for everyday use around your home.

Where can MCA (micronized copper azole) treated lumber be used?

You can use treated lumber indoors or outdoors, anywhere durability and resistance to decay are important. Most building codes require the use of pressure treated or naturally resistant wood species in components that will come into contact with concrete, masonry, or exposed soil. Its decay resistance makes it ideal for subflooring in kitchens and bathrooms. It is also highly recommended for outdoor applications – for gardens and walkways, playgrounds and decks.

What are the EPA’s guidelines for use of treated wood?

As with many building materials, the EPA has established a Consumer Information Sheet that outlines its recommendations for the use and handling of treated lumber. These guidelines should be adhered to in all home construction projects.  View Use & Handling guidelines located in our Information Library

Why shouldn’t treated wood be used for cutting boards or countertops?

The Food and Drug Administration discourages the use of any wood, treated or untreated, for cutting boards and countertops because these surfaces can become gouged during food preparation. Bacteria can grow in these gouges, creating unsanitary conditions in your kitchen. Only hard, abrasion-resistant materials should be used for cutting surfaces.

Why can’t treated wood be burned?

Fire unlocks the bond between the preservative and the wood cells, leaving behind metal residues in the ash. This could result in an environmental or health hazard if not disposed of properly. It is recommended that sawdust and scraps of treated material be disposed of through normal trash collection services or by burial.

Do I need any special equipment to use treated Southern Pine?

No special equipment is required to work with treated lumber. However, always make sure to use the standard safety equipment for any woodworking project – gloves, air filters (to filter out airborne sawdust when cutting), and protective eyewear.

What should I look for in purchasing pressure-treated wood?

First of all, look for a treated quality mark, which can appear either as an end tag or an ink stamp. This will assure you that the producer subscribes to rigorous quality control standards established by the American Wood Protection Association (AWPA) or the International Code Council (ICC). Culpeper Wood meets all of these standards.

A typical quality mark is illustrated below:


Like all lumber, treated wood is rated according to its usefulness for certain purposes. Be sure you purchase wood treated for the proper exposure conditions. Wood that is stamped for ABOVE GROUND exposure is ideal for applications such as decking or trim. Choose wood labeled GROUND CONTACT for applications where the wood will come into direct contact with the earth, is critical to the performance and safety of the structure, is installed less than 6” above the ground, has poor air circulation, may have leaf litter or other debris build up on the deck. The types of applications for GROUND CONTACT would be joists, beams, ledgers, posts, step stringers and in some applications, decking.

For a look at all the CWP quality marks, please click here.

Click here to view new treatment standards.

What type of nails and fasteners should I use with treated wood?

When you build with treated wood, you are building for permanence. Nails and fasteners must be able to last at least as long as the wood itself. When selecting a fastener for an outdoor project, make sure that it is manufactured for use with treated wood. Use only fasteners that are recommended by building codes and by the fastener manufacturer.

How should I install decking boards?

Wet after treatment deck boards should be installed by butting them tightly against each other. As the lumber dries, you can expect a 1/4" gap between the boards. When installing Culpeper KDAT (Kiln Dried After Treatment) boards you should leave a gap the width of an 8 penny nail (1/16”).

What should I apply to the field cut ends of treated lumber to give added protection?

Use an endcoat preservative. Brush-on endcoat wood preservative containing either Copper Naphthenate or Zinc Naphthenate is recommended on all saw cuts and into drill holes during construction of wood projects. Also apply on areas where moisture can collect. Follow endcoat maunfacturer's recommendations.

We suggest the following product which meets the requirements listed in the AWPA M-4 standard and Osmose warranty (click on the link below):

How long should I wait to seal my deck after installation?

In hot dry summer months, typically 2-3 weeks; in cooler months typically 4-6 weeks. For a wood sealant/finish to be effective the wood surface must be thoroughly dry. Here is a simple test. Splash water on the deck surface and observe its dispersion. If water droplets form on contact, the lumber is not yet dry enough to accept a finish. If water is absorbed into the wood it is time to apply/re-apply a wood sealant or finish.

How do I maintain the bright appearance of my deck?

Wash your deck once a year to ensure a clean surface and seal it with an oil-based water repellant product with UV protection from a Culpeper Dealer.