CSLB Class B General Contractor's License Practice Exam

What type of insulation is commonly used for exterior wall cavities?

1. Foam board insulation

2. Fiberglass insulation

3. Mineral wool insulation

4. Cellulose insulation

The correct answer is: Fiberglass insulation

Fiberglass insulation is widely used for exterior wall cavities due to its effective thermal resistance and versatility. It consists of fine glass fibers, which create a matrix that traps air, providing a barrier against heat transfer. This insulation is lightweight, cost-effective, and expands to fill wall cavities, minimizing gaps and enhancing energy efficiency. Additionally, fiberglass insulation is relatively easy to install, making it a preferred choice for both new constructions and renovations. It also resists moisture and most types of pests, contributing to the durability of the building envelope. Its availability in various forms, including batts, rolls, and loose fill, allows it to be adapted to meet a range of installation requirements in exterior walls. While other types of insulation like foam board, mineral wool, and cellulose also serve purposes in insulation applications, they are typically chosen based on specific project needs or conditions rather than as a standard for all exterior wall cavities. For instance, foam board insulation is often used in foundation applications or as an exterior continuous layer for thermal resistance, while mineral wool is more fire-resistant and commonly found in commercial applications. Cellulose insulation, which is made from recycled paper products, tends to be used in attics or dense-pack wall applications due to its settling characteristics. Thus, fiberglass remains