How it works

The mesh wraps the sidewalls of a chimney cap, allowing combustion gases to exit while intercepting any glowing particles carried by the exhaust. Burning embers cool and extinguish as they rest against the mesh or fall back into the flue. The 5/16-inch minimum opening prevents creosote and soot from clogging the mesh too quickly, while the 5/8-inch maximum stops virtually all dangerous-sized embers.

Sweeps clean spark arrestors during annual service because creosote accumulation on the mesh restricts draft and increases backdraft risk. A clogged spark arrestor can be a hidden cause of chronic smoking complaints, and inspection should always include checking mesh condition. Stainless mesh handles the heat and corrosion environment indefinitely; cheaper galvanized mesh degrades within a few seasons.

DFW context

DFW residential properties carry a moderate wildfire risk, particularly in semi-rural areas of Wise, Parker, and Denton counties where neighboring grasslands can ignite from chimney sparks. Properties with cedar shake roofs, though rare in modern DFW construction, also benefit from arrestor maintenance. TSE inspects and cleans spark arrestors during every CSIA Level 1 visit, and any damaged or missing mesh is replaced with stainless before the next burning season.

Related terms

• [Single-flue cap](/glossary/single-flue-cap/)
• [Multi-flue cap](/glossary/multi-flue-cap/)
• [Bird guard](/glossary/bird-guard/)
• [Animal guard](/glossary/animal-guard/)

Sources

• NFPA 211 (2024), Section 10.4.5
• IRC 2021, Section R1003.9.1
• CSIA Reference Manual