How it works

The chase frames a vertical box from dimensional lumber, sheathed and finished to blend with the home. Inside, the metal flue pipe rises with required air-space clearance to combustible framing, supported at code-mandated intervals. At the top, a galvanized or stainless chase cover seals the open top against weather while accommodating the pipe penetration and a storm collar.

Chase covers are the most common failure point. Many tract-built homes from the 1990s and 2000s shipped with bare-galvanized covers that rust through within 10 to 15 years, allowing water to enter the chase and rot the framing. Replacement with stainless steel or copper, fabricated with welded seams and a center cricket to shed water, is a permanent fix. Sweeps inspect chase condition during CSIA Level 1 visits.

DFW context

DFW suburban tract construction in Plano, Frisco, McKinney, and Allen produced thousands of chimney chases between 1995 and 2010, the majority with builder-grade galvanized covers. Two decades of Texas sun, hailstorms, and freeze-thaw cycles have left most of those covers leaking. The June 2025 hailstorms accelerated this failure pattern, and TSE fabricates and installs stainless replacements as a core service for these neighborhoods.

Related terms

• [Chase cover](/glossary/chase-cover/)
• [Class A chimney](/glossary/class-a-chimney/)
• [B-vent](/glossary/b-vent/)
• [Storm collar](/glossary/storm-collar/)
• [Prefab fireplace](/glossary/prefab-fireplace/)

Sources

• IRC 2021, Section R1004
• NFPA 211 (2024), Section 9
• UL 103 HT chimney standard