7 Signs Your Chimney Needs Repair Before Winter

Signs 1 & 2: The Masonry Itself

Start with the mortar joints. Healthy mortar sits nearly flush with the face of the brick. Failing mortar recedes, leaving shadowed gaps you can see from the driveway, and it turns sandy enough that a key or a screwdriver will dig it out with almost no pressure. If you are finding grit and small chips of mortar on the roof or in the gutters below the chimney, the joints are already open and water is getting behind the brick.

The second sign is spalling. Water that soaks into a brick and then freezes pushes the face of the brick off in flakes, leaving a pitted, crumbly surface or a shallow crater where the smooth face used to be. A handful of spalled bricks near the top is normal wear and gets patched. When spalling runs down several courses, the brick has lost its weather skin and repointing alone will not save it. That is the line between a repair and a rebuild, and it is worth knowing which side of it you are on before winter, not after.

Signs 3 & 4: The Top of the Stack

The crown is the sloped slab of concrete or mortar covering the top of the chimney, around the flue. Its entire job is to shed water away from the brick underneath. It is also the part of the chimney nobody ever looks at. Crowns crack because they are thin, exposed, and poured over a masonry structure that moves slightly with temperature. A hairline crack is a two-hour repair with a proper crown sealant. A crack you can slide a coin into is funneling water directly into the core of the chimney, where it will work its way down through the brick and out onto your ceiling.

The cap is the metal hood over the flue opening, usually with a mesh screen. Missing or rusted-through caps are common on older Bergen County homes, and the consequences are immediate: rain falls straight down the flue, birds and squirrels nest inside, and downdrafts push cold air and smoke back into the house. If you can see straight into an open flue from the ground, or you are hearing scratching from the fireplace, that is your sign. A cap is one of the cheapest parts of a chimney and prevents some of the most expensive damage. Our guide to chimney cleaning covers what else builds up inside an uncapped flue.

Sign 5: Stains That Aren't the Roof's Fault

Where the chimney passes through the roof, two layers of metal do the waterproofing. Step flashing tucks under the shingles along each side, and counter flashing is set into a groove cut in the mortar joints and folded down over the top of it. Both are supposed to move independently as the roof and the chimney shift. When the mortar holding the counter flashing gives out, the metal pulls loose, and water runs down the outside of the chimney and straight into the roof deck.

The tell from the ground is tar. If you see black roofing cement smeared around the base of your chimney, someone has already tried to stop a leak the cheap way, and that patch has a shelf life of a season or two. Inside, look for brown rings on the ceiling near the chimney chase, damp insulation in the attic on the chimney side, or a stain that appears only after wind-driven rain. These get diagnosed as roof leaks constantly. Because we handle both trades, the same crew that inspects your chimney can price the roof repair in Bergen County if the deck underneath has taken damage.

Signs 6 & 7: White Staining and Rust

White chalky streaks on the outside of the brick are called efflorescence. It is mineral salt carried out of the masonry by water moving through it, and it dries on the surface as the water evaporates. Scrubbing it off accomplishes nothing, because the staining is a symptom. It means water is traveling inside the chimney wall, and it usually shows up on the north and west faces first.

Inside the house, the equivalent signs are rust and damp. A damper that squeals, sticks, or will not seal is rusting, and dampers rust for exactly one reason. Same with rust stains on the firebox, a musty smell from the fireplace on humid days, or a hollow, ticking drip somewhere in the flue after rain. None of these are cosmetic. They are all telling you the water path is already open, and every one of them is cheaper to fix in September than in March. If the masonry damage extends past the chimney to steps, walls, or piers, our masonry repair crew handles that too.

What a Repaired Chimney Looks Like

These are chimneys we have repaired and rebuilt on New Jersey homes: joints repointed to match the original mortar, crowns re-poured with a proper overhang and drip edge, new caps set over open flues, and fresh flashing woven into the shingle courses so the seam is watertight instead of tarred over. Some of these started as a small crack a homeowner noticed from the driveway. A few had gone far enough that the top several feet came down and went back up. Click any photo to see it full size, and see the rest of our work on the project galleries.