Chimney repair in Geneva, IL
Tuckpointing, crown rebuilds, firebox work and flashing. We find where the water is getting in before we quote anything.
- Insured & Bonded
- 19 years in the trade
- Three brothers, one crew
- Open 7 days, 7am–8pm
Most chimney repair in northern Illinois traces back to water, not fire. Water soaks into brick and mortar during a thaw, freezes overnight, expands by roughly nine percent, and forces the material apart from the inside. It enters at three places: the crown, the flashing where the chimney meets the roof, and an open flue with no cap. Fixing the damage without closing the entry point buys two seasons, not a repair.
Smoke coming into the room, flames or roaring in the flue, or a carbon monoxide alarm sounding? Get everyone out and call the fire service first, then call us. We put these calls to the front of the queue.
Chimney flashing: the joint everyone gets wrong
Where a chimney passes through a roof there is a permanent gap between rigid masonry and a roof deck that flexes and settles. Flashing bridges that gap, and done properly it is two separate layers working together — not one.
Step flashing is a series of overlapping L-shaped metal pieces, one woven in with each course of shingles running up the sides of the chimney. Counter flashing is a second layer whose top edge is set into a groove cut into the mortar joint, then folded down over the step flashing. Water running down the brick hits the counter flashing and is thrown outward onto the step flashing, and from there onto the shingles. Done properly the two layers overlap like scales and there is no straight path in. Critically, the counter flashing is anchored into the masonry, not glued to the surface of it.
How it fails. The mortar groove erodes and the sealant shrinks, so the counter flashing lifts and water runs behind it. The metal corrodes or works loose after decades of thermal movement. Or — most commonly on re-roofed houses — somebody skipped the counter flashing entirely and ran a thick bead of roofing tar around the joint instead. Tar is rigid, the joint moves constantly, and it cracks within about two years. Because it is black and opaque you cannot see that it has failed; it just quietly stops working.
How to spot it. Water appearing only after wind-driven rain from one direction but not after steady gentle rain is a strong flashing signal. So is a stain beside the chimney breast in an upstairs room or attic rather than directly under a roof plane, and rusty streaks on the metal at the roofline. If you can get into the attic with a torch during a downpour you can often watch exactly where it comes in.
Re-seal or reflash. If the metal is sound and only the mortar groove and its sealant have failed, we rake the groove out properly and re-bed the counter flashing — a genuine repair that lasts. If the metal is corroded, fatigued, or was never a proper two-layer system, sealing it again buys two more years. On materials: aluminium is cheap and common, copper costs more and outlives the roof, and lead-coated copper is what we would use on a chimney expected to still be standing in fifty years. What we will not do is smear tar around a failed joint and call it fixed.
Crowns
The crown is the slab on top sealing the masonry around the flue opening. A proper crown is cast concrete, sloped to shed water, overhanging the brick by an inch or two with a drip edge cut underneath so runoff falls clear instead of running down the face, and with an expansion joint around the flue tile.
What most houses actually have is a thin skim of ordinary mortar, flush with the brick, with no overhang and no drip edge. Mortar is a bedding compound, not a weather surface. It cracks within a few years and water goes straight into the top of the wall.
Fine surface cracking can usually be sealed with a flexible crown coating — a good outcome for modest money. Once it has cracked structurally it needs cutting off and recasting properly. Telling those apart is a judgement made with photographs, not from the ground. See caps and crowns.
Tuckpointing
Mortar is deliberately softer than the brick around it — it is the sacrificial element, absorbing movement and moisture so the masonry units survive. Over decades of Illinois freeze-thaw the joints erode, recede, and eventually let water straight into the wall.
Done properly, joints are raked out to a depth of roughly two to two and a half times the joint width before repacking. A shallow smear of new mortar over the face of a failed joint looks tidy for a season and falls out within a couple of winters. It is the most common shortcut in the trade and it is invisible on the day the work is finished.
Mortar type matters just as much. A lot of older property around Geneva and Batavia has limestone in the chimney or soft historic lime mortar. Repointing that with a hard modern portland mix creates pointing stronger than the surrounding stone, so water gets trapped and the masonry unit spalls instead of the mortar — the opposite of what mortar is for, and far more expensive to put right.
Timing
Mortar will not cure properly below about 40 degrees, so exterior masonry is warm-weather work. That is worth knowing in autumn: if your joints or crown are visibly failing, this season is the window. A cracked crown left through an Illinois winter is a full season of freeze-thaw working on the top of your chimney.
Interior work and inspection carry on year round.
Stain on the ceiling by the chimney?
We check all three entry points and tell you honestly when it is a roofing job instead.
Chimney repair questions
How do I know if it is the roof or the chimney?
Position and timing. A stain beside the chimney breast, appearing after wind-driven rain from one direction, usually points at the chimney. We check the chimney entry points first and say so plainly when the answer is a roofer.
What separates correct flashing from the tar most houses have?
Two layers. Step flashing woven in with the shingle courses up the sides, and counter flashing whose top edge sits in a groove cut in the mortar and folds down over it. Tar is not flashing.
We had a new roof and now there is damp by the chimney. Coincidence?
Usually not. Reused old flashing, or roofing tar smeared around the joint instead of proper counter flashing, is one of the most common causes of chimney leaks after a re-roof.
Can a cracked crown be repaired rather than replaced?
Fine surface cracks can be sealed with a flexible crown coating. Structural cracks, or a crown broken into pieces, needs cutting off and recasting.
How deep should mortar joints be raked out?
Roughly two to two and a half times the joint width. A shallow surface smear over a failed joint fails within a couple of winters.
Why does mortar type matter?
Mortar should be softer than the masonry around it. A hard modern mix on soft historic brick or limestone traps water and makes the masonry spall instead of the mortar.
Can chimney repair be done in winter?
Inspection and interior work, yes. Exterior masonry needs above roughly 40 degrees to cure, so it gets scheduled for milder weather.
How do you price repairs?
After an inspection, never before. Starting figures are on the pricing page so you have a sense of scale.
Other things we do
All eight services come from the same three people.
Chimney sweeping · Chimney inspection · Chimney relining · Chimney caps & crowns · Gas fireplace service
Written by Rick Lee, owner of Zenith Chimney Service, Geneva IL. Published September 4, 2026.