Which of the following is the most common wood preservative used in Idaho?

Chromated Copper Arsenate (CCA) is the most common wood preservative used in Idaho primarily due to its effectiveness in preventing decay and insect damage in wood products. It is a water-based preservative that contains chromium, copper, and arsenic, which work together to protect wood from biological threats such as fungi and termites. The high level of efficacy makes it suitable for various outdoor applications, including residential and commercial structures.

Additionally, CCA-treated wood is widely recognized and has a long history of use in the construction industry, which contributes to its popularity. It allows for greater longevity of wood products, reducing the need for frequent replacements, which is particularly important in areas where wood is exposed to moisture, pests, or harsh environmental conditions.

Other options like polyurethane, varnish, and pine oil are not primarily used as wood preservatives in the same context. Polyurethane and varnish are primarily protective finishes that enhance appearance and provide some moisture resistance but lack the protective qualities against biological threats that CCA offers. Pine oil, while having some antimicrobial properties, is not used as a wood preservative in the same manner as CCA and is more often seen in cleaning products or natural wood treatments rather than in construction materials.