What can cause a blockage in a chimney system?

Blockages in a chimney system can occur due to various factors, and both animal nests and soot buildup are common contributors.

Animal nests, such as those made by birds or squirrels, can obstruct the flue. These nests create physical barriers that prevent smoke and gases from exiting through the chimney, potentially leading to dangerous backdrafts or chimney fires. Additionally, animals may get trapped within the chimney, creating further complications.

Buildup of soot, on the other hand, is a result of the incomplete combustion of fuel within the fireplace or stove. As wood, coal, or other fuels burn, they release particulate matter that can accumulate on the interior surfaces of the chimney. Over time, this residue can thicken and harden, narrowing the flue and restricting airflow. This soot accumulation is highly flammable and poses a significant risk of chimney fires if it reaches a critical mass.

Since both factors can lead to serious safety concerns and affect the efficiency of the chimney system, the correct answer reflects that either condition can independently contribute to a blockage.