The chemicals used to pressure treat wood aren't safe for humans, this is why non-pressure treated wood is still required for use indoors, and why builders recommended that you only use pressure treated lumber for your outdoor projects like decks, pergolas, etc.
Chemical risks.
Because this type of decking is treated with chemicals for protection, it can be hazardous when not handled correctly. If the wood is burned, trimmed, or cut, it can release harmful toxins into the air. Pressure-treated wood should not be used for gardens or come in frequent contact with food and water.
While treated wood has distinct advantages, you might decide that they aren't worth the added health risk. Yet, if you need something to last a long time and you know people won't come into much contact with it, treated lumber might be the better choice.
Pressure-treated wood should be used for all outdoor projects, assuming you're using a type of wood that is not naturally repellant to insects and rot. That said, not all pressure treatments are created equal. The two main types of PT lumber are above-ground and ground-contact.
Moisture Problems and More
After chemical pressure treatment, PT lumber must dry quite a bit before you use it in construction. Some builders use the wood before it dries and hope that the anchoring of nails and fasteners will prevent its twisting as it dries.
Pressure treated wood needs time to dry out before it's primed or painted. You can expect 3-4 months before the moisture levels fully go down. If moisture beads up on the surface, it's still too damp. You'll know the treated wood is ready to paint when it absorbs water instead of repelling it.
Although treated wood is protected against decay and termite attack, the application of a water-repellent sealer to all exposed wood surfaces is recommended upon completion of construction.
When it comes to comparing treated wood vs. cedar, pressure-treated wood is the sturdier and more weather-proof of the two. It's highly resistant to insect attack and rot, and special versions rated for “ground contact” can be buried in soil and will continue to shrug off decay for decades.
Many people assume that any type of wood can withstand harsh outdoor elements, but the truth is if you use non-pressure-treated wood outside, it can be exposed to rot, decay, insect infestations, and structural failures.
Ground-contact lumber is, as the name suggests, suitable for contact with the ground. It's commonly used for pressure-treated posts and some framing. Containing a greater amount of chemical treatment, these wood products can last much longer than aboveground lumber, and up to 40 years, in some cases.
If you're looking for a durable, long-lasting material that's resistant to rot and decay, cedar is a good choice. Cedar is more expensive than pressure-treated wood. Cedar has a more natural look that many people find appealing.
Naturally Resistant
To deter the pests, homeowners can obtain heartwood-grade lumber for construction projects. Termites also tend to avoid specific species of trees such as redwoods, yellow cedar, Laotian teak, and cypress. However, these types of wood are not as long-lasting as treated lumber.
Use pressure treated wood in any situation where there's direct contact between the wood and anything that could supply moisture. This means posts in contact or buried underground obviously, but it also includes any lumber touching concrete or masonry since it's porous and wicks water like a sponge.
Well, until about 2003, the chemical used to pressure treat wood was chromated copper arsenate (CCA), which, as the name suggests, contains arsenic. Arsenic is a poisonous compound, and there is a risk that over time, it may leak out of the wood, and could come into contact with someone walking barefoot on a deck.
The chemical preservatives used to produce pressure-treated wood minimize the wood's natural vulnerability to insects and rot, but they also leave the wood rather wet, a state that could lead to your coat of paint eventually peeling.
While selecting brown timber may be more desired due to its traditional appearance, it's worth noting that the dye is added as an industrial preservation process rather than a decorative finish as eventually all treated timber will fade in colour over time (this can be prevented by regular maintenance).
The outdoor elements can take a toll on wood and make it look less than pristine. Pressure treatment helps protect wood from rot and insects with the help of high pressure and preservatives, helping to extend its life. Generally, pressure-treated wood can last anywhere from 10 to 40 years, depending on a few factors.
Normal rainwater will not harm the wood that is used to build homes. Many homeowners fear that wood will immediately rot if allowed to get wet. That's simply not the case. The only thing that doesn't fare well if it gets wet is low-grade OSB.
All pressure treated wood, cedar, and redwood are susceptible to damage from sunlight, rain, and snow. Pressure treated lumber does come with a lifetime warranty against rot, decay, and termite damage, but pressure treatment does not protect against weathering cycles of wetting and drying.
Brown timber follows the same treatment process as Green timber. The only difference is a Brown dye, which is added to the copper preservatives mix. This gives the timber a traditional dark Brown appearance that most homeowners will be more familiar with.
#1 Grade: When appearance becomes more of a factor, #1 Grade will contain smaller, fewer, sound, tight knots and have less wane than found in #2 Grade. Keep in mind, that with the introduction of Prime grades, #1 Grade no longer contains some of the better grades that used to be included.
Overall, our experts at Patio Productions recommend Cedar or Redwood as the best wood choice for outdoor decks.
Yes. Although pressure-treated lumber is pre-treated with chemicals, preventing insect damage, it is NOT waterproofed. In fact, the chemical treatment actually causes the lumber to dry out quicker and absorb more water than untreated lumber.
Once dry, these wood fibers can remain raised and may cause splinters. For this reason, light but thoroughly sanding your wood deck is a necessary step before staining or sealing. This crucial step will ensure that your refinishing job gives great results.
All wood, except manufactured products like composite wood — even pressure-treated lumber — need to be sanded and stained. If you want it to last, you have to put in the time and some elbow grease.