What is placed around a chimney to prevent leaks?

Flashing is a critical component used around chimneys to prevent leaks. It is made from materials like metal or a waterproof membrane that is installed at points where water might enter, especially where the chimney meets the roof. The purpose of flashing is to redirect water away from vulnerable areas and ensure that there are no openings through which moisture can seep in. Properly installed flashing creates a barrier that keeps the roof and chimney junction watertight, which is essential for preventing water damage to the home’s structure.

Sealant could be used in conjunction with flashing to further waterproof the area, but it doesn't serve as a structural barrier like flashing. Insulation is important for energy efficiency but is not designed for preventing leaks. Cladding refers to the exterior covering of a building, which does not have a direct role in waterproofing the chimney area. Thus, flashing is specifically designed for this purpose, making it the appropriate choice in this context.