How often to sweep a chimney in San Antonio
The fire code answer is an inspection every year. The practical answer depends on how much you burn, and in San Antonio most people burn less than they think, but not as little as they hope.
The rule
NFPA 211 is the national fire code for chimneys. It says chimneys and vents shall be inspected at least once a year for soundness and freedom from deposits. Cleaning and repairs follow if needed. The US Fire Administration and the CDC give the same advice: have the chimney checked every year.
The inspection is yearly. The sweep happens when the inspection finds buildup. For most wood-burning fireplaces used regularly, that is every year too.
How much San Antonio actually burns
We counted every night from 1996-97 to 2024-25 at San Antonio International Airport. The low reached 45F or colder on about 75.7 nights a winter, and freezing on about 13.8. January averages 21.1 of those cool nights, December 19.4, February 14.5 and November 9.3.
Average nights at or below 45F, by month, San Antonio
So a San Antonio fireplace might be lit a few dozen evenings a winter. That is enough to build creosote, especially with wood that is not fully dry, and the long idle season in between is when birds and squirrels move into the flue.
A simple schedule
| How you use it | Inspection | Sweep |
|---|---|---|
| Wood, most cold weekends or more | Every year | Every year |
| Wood, a handful of fires a winter | Every year | When the inspection finds buildup |
| Gas logs or a gas insert | Every year (venting and burner) | Rarely needed |
| Not used in years | Before the first fire | Usually needed after years of nests and debris |
Our summary of NFPA 211's yearly-inspection rule, applied to San Antonio use. Your sweep may recommend otherwise after looking.
Timing it around the swifts
TPWD's guidance for sweeps is to delay cleaning at least 6 weeks for a chimney with eggs and at least 4 weeks for one with young, and that late fall, after the swifts have gone south, is the better time to clean. In San Antonio that means October to early November, or March. Chimney swifts.
Questions San Antonio homeowners ask
Can I go two years without cleaning my chimney?
If you burn very little and a yearly inspection finds little buildup, maybe. The inspection itself should still be yearly.
How do I know my chimney needs cleaning?
Black flakes falling into the firebox, a campfire smell when it is not in use, smoke that won't draw, or a layer of soot you can scratch more than about an eighth of an inch deep inside the flue.
Does burning a creosote log replace sweeping?
No. Creosote treatment logs can loosen some deposits but don't remove them, and they don't inspect anything.
Sources
- Chimney Safety Institute of America: Homeowner Resources (quotes NFPA 211 on annual inspection)
- US Fire Administration: Heating Fire Safety (2021 national estimates)
- CDC: About Carbon Monoxide Poisoning
- Texas Parks and Wildlife, Texas Partners in Flight: Chimney Swifts, Tips for Homeowners and Chimney Sweeps
- NOAA NCEI: GHCN-Daily, San Antonio International Airport (USW00012921), through October 24, 2026