While naturally resistant to rot and decay, Western Red Cedar shingles and shakes that have been treated with Chromated copper arsenate (CCA) will add years to the life of your roof or siding.
Invented in the early 1930’s, CCA treatments protect wood against insect attack and fungal decay and is expected give life to the wood in the excess of forty years. This can be extremely helpful in areas with high humidity to provide longevity to cedar roofing, utility, highway, marine, agricultural and heavy construction. CCA preservative treatments render the wood useless as a food substance for insects and fungi; yet keeps the natural look of the wood. As a matter of fact, it is almost impossible to tell that the wood has even been treated when finished.
Since CCA pressure treatments have been around for so long, many studies have been done to ensure its safety by both private and public research institutions. At no time have any special risks been found and it is not toxic to plants. However, it should not be used in direct contact with food, nor should it be burned. As with any wood, a dust mask should be worn when sawing or working with CCA treated cedar shingles and shakes.
Building a quality project starts from the ground up. That’s why we only purchase the best quality Pressure Treated building materials approved for ground contact with good quality retention ratings.
What does this mean?
Like any product, there are various Pressure Treated building materials that are manufactured with different quality standards. And, while you may find Pressure Treated products for less money at mass retailers or other lumber yards; be sure when comparing pricing, you also compare quality.
Retention level refers to the amount of preservative that remains in the wood after the pressure treatment process is complete. It is measured on a weight basis and is typically expressed as pounds of preservative per cubic foot (pcf) of wood. There are a number of typical retention levels available. Generally, the harsher the condition the wood is exposed to, the higher the retention level must be.
There are many types of Pressure Treatments for building materials, however the three types traditionally we provide for our customers are:
ACQ ~ ACQ stands for Alkaline Copper Quaternary. The ACQ preservative system is based on the well-established effectiveness of copper combined with a co-biocide. ACQ Pressure Treated building products are usually used for sill plates, patios, deck substructures, fence posts and landscaping structures. The minimum retention level for ACQ Treated Wood for ground contact purposes is 0.40 pcf.
ACQ Treated Wood is generally backed with Limited Warranty by the manufacturer against structural damage caused by decay and termites. ACQ Treated Wood meets American Wood Protection Association (AWPA) standards as well as all major model building code requirements.
ACQ Treated lumber is also approved by the NAHB Research Center and certified by Scientific Certification Systems (SCS) as environmentally preferable. Approved products are now eligible to receive points towards a building being certified under the National Green Building Standard.
CA-C ~ CA-C stands for Copper Azole, type C. Copper Azole preservative renders wood useless as a food source for termites and fungi. CA-C incorporates a combination of synergistic azoles; the type C formulation is the most advanced version available commercially. Common uses for CA-C for ground contact applications include: poles and posts, wood foundations, utility poles and guardrails. The minimum retention for level for CA-C treated wood is 0.14 pcf.
CA-C Treated Wood meets requirements of model building codes for many applications; it is also listed in the standards of the American Wood Protection Association (AWPA). In addition, a code evaluation report (ICC-ESR-1721) has been issued for this product.
Generally, a limited warranty against rot and insect damage is provided by the manufacturer on CA-C Treated lumber.
CCA – CCA stands for Chromated Copper Arsenate. CCA is a chemical wood preservative containing chromium, copper, and arsenic. CCA is used in Pressure Treated building materials to protect it from rotting due to insects and microbial agents. The Environmental Protection Agency (EPA) has classified CCA as a restricted use product for industrial and agricultural applications only. It is not approved for residential uses.
Special considerations and caution should be taken when using any lumber that has been treated with a preservative. It should not be used in any circumstance where it may come into contact with drinking water or where the preservatives could come in contact with food, animal feed or beehives.
photo and craftsmanship by Soundecks of Anacortes, WA
When working with Pressure Treated lumber, gloves should be worn. In the event direct contact is made, all exposed skin should be washed thoroughly. During cutting, it is advised that you wear a dust mask and goggles. Never burn preserved wood.
Because of the corrosive nature of all types of Pressure Treating, high quality corrosion resistant nails, screws, fasteners and hardware must be used.