San Antonio does not get the long freeze-thaw winters that grind down chimneys in the north. What it gets instead is the occasional hard freeze dropped on masonry that has spent nine months soaking up rain and baking in 100-degree heat. Winter Storm Uri in February 2021 was the extreme case, but January 2024, January 2025 and the winter of 2026 each brought a cold snap in the teens and twenties. This post covers what those events do to crowns, brick, flashing and prefab chase covers, what a chimney inspection looks for afterward, and what repairs typically cost.
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The freezes, by date
These are the recent events, read from NOAA records for San Antonio International Airport and the National Weather Service event summary for 2021:
- February 15, 2021 (Winter Storm Uri): a low of 9 °F, with the airport “below freezing for 4 days 12 hours,” one hour shy of the record set in 1951.
- January 17, 2024: a low of 18 °F after four straight mornings in the low twenties.
- January 21–22, 2025: light snow on January 21 and a low of 24 °F on January 22.
- Winter 2026: a season minimum of 20 °F.
For context, the 1991–2020 normals give San Antonio just 14.0 nights a year at or below 32 °F, 0.2 inches of snow and 17.7 days at or above 100 °F, with 32.38 inches of rain concentrated in May (4.40 inches) and September–October. That combination, wet-dry cycling through a hot year punctuated by a rare deep freeze, is what shapes chimney damage here.
Wet-dry cycling, then freeze-thaw: how the damage happens
Masonry absorbs water. A crown with a hairline crack, a mortar joint that has lost its face, or an uncapped flue lets rain into the structure every time a front comes through, and the heat that follows drives it back out. That wet-dry cycling slowly opens the pores and the cracks. When a hard freeze arrives, the water in those openings expands as it turns to ice, and a hairline in October can be a visible gap by March. One freeze rarely wrecks a sound chimney; it finds the weak spot moisture already created.
The homes most exposed are the ones with the most masonry. About a third of Bexar County’s housing units were built before 1980 (ACS 2024 1-year), and the 1950s–70s masonry chimneys in Alamo Heights, Terrell Hills and Monte Vista have had decades of cycles. The 1980s–2000s subdivisions have a different weak point, covered below.
Crown cracks
The crown is the sloped concrete or mortar slab that caps the top of a masonry chimney around the flue tiles. It takes the most sun and rain, and it is where freeze damage usually shows first: hairline cracks that widen, edges that break away, and gaps where the crown meets the flue tile. A cracked crown is also the main route for water into the chimney body. Repair options range from a brushable or trowelled crown coating for minor cracking to a full rebuild of the slab.
Spalling brick and open mortar joints
Spalling is when the face of a brick pops off, leaving a rough, recessed surface and a pile of flakes on the roof or at the base of the chimney. It happens when water inside the brick freezes and pushes the face away. Mortar joints fail the same way, crumbling or receding so that the bricks around them loosen. Tuckpointing restores the joints; badly spalled bricks are cut out and replaced; and if the damage reaches the upper courses, the section above the roofline may be partially rebuilt.
Flashing leaks and rusted prefab chase covers
Flashing is the metal that seals the joint between the chimney and the roof. Freezes stress the sealant and the step flashing on stucco and stone-veneer chimneys, and the first sign is usually a stain on the ceiling near the fireplace or water in the firebox after a storm. Caught early, it is a small repair.
Most 1980s–2000s San Antonio fireplaces are prefab (factory-built) units venting through a metal pipe inside a framed chase, topped by a sheet-metal chase cover rather than a masonry crown. Galvanized covers rust, standing water pools on flat ones, and a freeze can open a rusted seam enough to drip straight down the chase. Rust streaks on the siding below the cover are the tell. A stainless replacement cover ends the cycle.
What a Level 2 inspection looks for
NFPA 211 defines three inspection levels. A Level 1 is the visual check that comes with a routine sweep. A Level 2 adds a camera scan of the flue and is the level called for on sale or transfer, a fuel change, a new appliance, or after a malfunction or event. A hard freeze that leaves new cracking, staining or debris in the firebox is that kind of event. A Level 3 opens up concealed areas and is reserved for suspected serious damage.
After a freeze, the technician doing a Level 2 chimney inspection will typically document, with photos:
- Cracked, shifted or spalled flue tiles and gaps in the joints between them
- Water staining inside the flue and smoke chamber, and debris that has fallen from above
- Crown condition, cap and spark-arrestor condition, and whether the chase cover holds water
- Flashing, counter-flashing and the roof deck around the chimney
- Firebox and refractory panels, damper operation and the condition of the exterior masonry
A Level 2 inspection typically runs $150–$1,000; a camera look added to a sweep is about $50–$75 more (typical national ranges from Fixr (2025) and Angi via Bob Vila (2023) — estimates, not quotes). Ask for the video or photo record; it is your evidence for any later conversation.
What repairs typically cost
These are typical national ranges from Fixr (2025) and Angi via Bob Vila (2023) — estimates, not quotes. A written quote after an inspection is the only real number.
| Repair | Typical range |
|---|---|
| Crown repair / replace | $750–$1,000 / $1,000–$3,000 |
| Flashing repair / replace | $200–$300 / $300–$800 |
| Tuckpointing (chimney) | $500–$2,500 |
| Chase cover replacement | $300–$700 |
| Waterproofing / sealing | $150–$500 |
| Chimney rebuild (partial) | $500–$4,000 |
| Chimney relining | $1,800–$4,000 (avg about $2,500; up to about $7,000) |
If the damage might be covered by a homeowner’s policy, ask your insurer what your policy covers. The inspection report and photos are what you will need either way. Our crown, flashing and masonry repair page describes each repair in more detail.
Who does the work, and permits
Texas has no masonry, roofing or general-contractor license. Inside San Antonio city limits, nonstructural repair work such as crowns, flashing, tuckpointing and relining calls for a City of San Antonio Home Improvement Contractor registration; structural work needs a Residential Building Contractor, per Development Services interpretation CI-2025-005. Whether a rebuild or reline needs a building permit is not stated on the City’s pages, so the contractor confirms with Development Services. In historic districts such as King William, Monte Vista and Dignowity Hill, exterior work needs an Office of Historic Preservation Certificate of Appropriateness. Outside city limits, permits vary by city; your contractor confirms.
Ask any company for proof of insurance, a written scope with photos, and whether its technicians hold a CSIA Certified Chimney Sweep or NFI certification (private credentials; verify on csia.org or nficertified.org). Then request a free quote; we usually reply the same day. Our chimney sweep cost guide has the full price table.
Frequently asked questions
Does a hard freeze damage a chimney in San Antonio?
It can, especially when water was already in the masonry. The airport fell to 9 °F on February 15, 2021 and stayed below freezing for 4 days 12 hours, then hit 18 °F in January 2024, 24 °F in January 2025 and 20 °F in winter 2026. Water in a hairline crown crack or behind a loose brick expands as it freezes, and each event can widen damage that a mild winter would not.
What does a Level 2 chimney inspection look for after a freeze?
A Level 2 inspection adds a camera scan of the flue to the visual checks of a Level 1. NFPA 211 calls for a Level 2 after a malfunction or event, and a hard freeze qualifies when there is new cracking, staining or debris. The technician looks for cracked or shifted flue tiles, water entry, gaps in mortar joints and damage to the crown, cap, flashing and firebox, and documents it with photos.
Can chimney repair be done in winter in San Antonio?
Usually, yes. NOAA’s 1991–2020 normals show only 14.0 nights a year at or below 32 °F and 0.2 inches of snow, and December through February is the driest season at 5.70 inches of rain, so most days are workable. Mortar, crown coatings and sealants have minimum temperatures, so the company may schedule around a cold front. Emergency measures such as a tarp or temporary cap can go on any time.