Longmont Chimney Trouble: Five Signs That Call for Repair Now
Some chimney problems can wait for the next scheduled visit. These five cannot: smoke or fumes coming into the house, signs of a chimney fire, a leaning or crumbling stack, water getting inside, and pieces of liner or crown falling into the fireplace. If you notice any of them, stop using the fireplace or stove and have it looked at.
Signs that involve smoke, gas or fire
1. Smoke, fumes or a carbon monoxide alarm
A chimney that pushes smoke into the room, or a carbon monoxide alarm that sounds, means gases are not leaving the house as they should. The cause may be a blocked flue, a collapsed liner, a nest, a damper that is stuck, or a pressure problem in the house. Whatever the cause, it is a health risk.
What to do: put out the fire if it is safe to do so, get everyone into fresh air, and if an alarm went off, call for help from outside. Do not use the fireplace or any gas appliance venting into that chimney until it has been checked.
2. Signs of a chimney fire
Chimney fires are not always dramatic. Signs that one has happened include:
- a loud roaring or rumbling sound from the chimney during a fire, or popping and crackling inside the flue;
- puffy, honeycomb like creosote flakes in the firebox or on the roof;
- cracked or missing flue tiles, or pieces of tile in the fireplace;
- a warped damper or discolored, distorted cap;
- cracks in the exterior masonry or smoke escaping from them.
What to do: if a chimney fire is happening, get everyone out and call 911. Afterward, NFPA 211 points to a Level 2 inspection, with a camera through the flue, before the chimney is used again.
Signs that involve structure and water
3. A leaning, separating or crumbling stack
A chimney that tilts, pulls away from the wall of the house, or has loose and missing bricks near the top can fall. That is a danger to people below and to the roof, and it often means water has been undermining the structure for some time.
Wind makes this more urgent. The National Weather Service summary of the March 13 to 14, 2021 blizzard notes that wind gusted to 40 or 50 mph at many points along the I-25 corridor. Strong winds and heavy snow put extra load on a weakened stack.
What to do: keep people and vehicles away from the area below the chimney, do not use the fireplace, and arrange a repair quickly.
4. Water inside: in the firebox, on the ceiling or in the attic
Water pooling in the firebox, a rusty damper, a spreading stain on the ceiling near the stack, or damp wood in the attic around it all mean water is getting past the cap, crown, flashing or masonry. Left alone, it rots framing and roof sheathing, and each freeze widens the gaps that let it in.
What to do: note where the water appears and when, after rain, snowmelt or wind, since that helps trace the source. Our article on how water and freezing damage chimneys explains the common entry points.
5. Pieces of liner, brick or crown falling
Bits of clay tile, brick, mortar or concrete in the firebox, on the smoke shelf, on the roof or in the gutters mean something is breaking down. Tile fragments are the most serious, because a damaged liner can let heat reach wood framing.
This is a common finding in older chimneys. By the Census Bureau's 2020 to 2024 estimates, about 37 percent of Longmont's homes were built before 1980, and a flue that old has been through decades of heating and freezing.
What to do: leave the fireplace cold and arrange a camera inspection of the flue, which shows where the fragments originate.
Why acting quickly matters
Each of these signs points to a problem that tends to get worse quickly: a fire hazard, a gas hazard, a structural risk or active water damage. Dealing with them early usually means a smaller repair, and above all it keeps the household safe. Our chimney repair page lists the kinds of repairs involved, from liners to crowns and masonry.
Longmont winters give small faults plenty of help. Going by NOAA's 1991 to 2020 normals, nights at or below freezing are the rule rather than the exception from November through March, so a crack or a gap noticed in the fall can be visibly worse by spring.