Chimney Flue Installation in San Antonio, TX

Sizing is governed by the appliance and code, not guesswork. For an open masonry fireplace, NFPA 211 and the IRC generally require the flue's cross-sectional area to be proportional to the fireplace opening — commonly around one-tenth for a round flue and one-eighth to one-tenth for square or rectangular flues, depending on chimney height. An undersized flue spills smoke and slows draft; an oversized one cools gases and accelerates creosote. We calculate from the opening and the appliance listing, then confirm against code.

Both, and they're linked. The 3-2-10 rule — flue terminating at least 3 feet above the roof penetration and 2 feet above any structure within 10 feet — exists so combustion gases and sparks clear the roof and so the chimney develops reliable draft. A flue that's too short can backdraft, pushing carbon monoxide and smoke into living space, and can drop embers onto nearby roofing. We set termination height to code as part of any new flue installation.

It depends on the system. Masonry flues built into masonry chimneys require a code clearance from combustible framing — typically 2 inches for interior chimneys and 1 inch where the chimney is on an exterior wall. Listed metal chimney systems carry their own clearance in the manufacturer's instructions, which the code requires us to follow exactly. Getting this gap right is the difference between a compliant install and a slow-charring fire hazard, so it's verified and documented.

Often yes — many flue installations are effectively relining an existing chimney with a properly sized, listed liner. A flue must be continuous, correctly sized, and rated for the fuel. If the existing masonry flue is cracked, unlined, or the wrong size, installing a UL-listed liner restores a safe, code-compliant path for combustion products. We inspect the existing structure with a camera first so the new flue solves the real condition rather than masking it.

Yes — our crews cover San Antonio's 110 ZIP codes across Bexar County, including Alamo Heights line, Stone Oak, Monte Vista, plus the surrounding communities.

We offer same-week scheduling across San Antonio, booked by a real person in under two minutes, 7 AM to midnight every day.

San Antonio's deep housing range — from the 1920s masonry of Monte Vista and King William to the newer construction in Stone Oak — means our CSIA-certified inspectors apply the full NFPA 211 framework across vastly different chimney ages. Historic districts along the Alamo Heights line frequently reveal unlined clay-tile flues and deteriorated mortar that only Level 2 video can fully document, while Stone Oak's prefab systems need clearance and liner verification. Across the city, we focus inspection on the smoke chamber and flue transitions where creosote concentrates and structural cracking begins. Chimney Flue Installation is part of keeping that local housing stock safe, efficient, and up to code.