By Daniel Watkins, Noble Chimney Sweepers.
Summer storms do more damage to chimneys than winter does, which surprises people. Winter is hard on masonry that is already compromised. Summer is what compromises it. Wind-driven rain, hail and the sheer volume of water in a July downpour find every gap, and the damage stays hidden until the first freeze turns it into something structural.
Water is the mechanism behind nearly every masonry failure
A chimney is the only part of your house exposed to weather on all four sides and from above, with no roof over it and no siding. Brick and mortar are porous. They take on water, and in a normal season they dry out again. The trouble starts when water gets somewhere it cannot easily leave.
Then winter arrives. Water trapped in masonry expands as it freezes, pushing the material apart from the inside. Our climate delivers repeated freeze-thaw cycles rather than one long freeze, so the process repeats dozens of times a season. Each cycle widens what the last one opened. A hairline crack in August is a spalled brick face by March.
What to look at before the weather turns
The crown
The crown is the sloped concrete slab across the top of the chimney, and it is the single most important piece for keeping water out. It should shed water away from the flue and overhang the brick slightly. Cracks in a crown are common and they funnel water directly into the chimney structure. Many crowns in this area were poured too thin or without an expansion joint around the flue tile, and those fail early.
The mortar joints
Mortar is deliberately softer than brick, so it erodes first. That is by design. Joints that have receded noticeably, feel sandy, or can be scratched out with a key are past due for tuckpointing. Left alone, water runs straight into the wall through the missing joint.
The flashing
Flashing is the metal that seals the joint between the chimney and the roof. It is the most common source of ceiling stains near a chimney, and the failure is usually sealant that has dried and split rather than the metal itself.
The brick faces
Look for faces that have popped off, leaving a rough lighter-colored patch. That is spalling, and it means water got in and froze. Spalled brick does not heal and the exposed interior absorbs water faster than the original face did.
Why late summer is the right time to fix it
Masonry repair depends on temperature. Mortar needs to cure above freezing, and sealants and crown coatings have minimum application temperatures. Once nights turn cold, the window for doing this work properly closes until spring. Waiting means either a rushed repair in marginal conditions or a full winter of the damage getting worse.
Older housing stock in Plainfield and the surrounding area includes a lot of chimneys now well past the point where their original crowns and joints can be expected to perform, and the ones that get looked at in August are the ones that make it through February without incident.
Repair scope varies enormously, so get it assessed
The gap between a crown seal and a partial rebuild is large, and the only way to know which you are facing is to have someone look properly. Our chimney repair work starts with an assessment of what is actually failing, because sealing a crown on a chimney whose real problem is failed flashing accomplishes nothing.
An assessment is also the point at which a hidden liner problem surfaces. Water that has been entering for years frequently damages the flue liner as well as the exterior, and that is a safety issue rather than a cosmetic one. Our chimney inspection covers the interior so you are not repairing one half of a problem.
Prices are published on the pricing page and you get the figure up front. We are certified, bonded and insured, and after fourteen years I would rather tell you a crack is cosmetic than sell you a rebuild you do not need. Call (708) 432-5747, seven days a week, 7 AM to 7 PM.
Frequently asked questions
How do I know if a crack in the crown is serious?
Width and depth matter more than length. Hairline surface crazing is often manageable with a proper crown coating, while cracks you can fit a fingernail into, or that run through the full thickness, allow water into the chimney and need real repair.
Is tuckpointing the same as repointing?
In everyday use the terms are used interchangeably for the same job: raking out deteriorated mortar to a sound depth and replacing it with fresh mortar. What matters is that the new mortar is matched to the existing masonry rather than simply being strong.
Should I seal my chimney with waterproofing?
A breathable masonry water repellent can be worthwhile on sound brickwork, because it repels liquid water while still letting vapor escape. Applying a non-breathable sealer traps moisture inside the wall and makes matters worse, so the product choice is not a detail.
Why is there a white powdery residue on my brick?
That is efflorescence, mineral salts left behind as water moves through masonry and evaporates at the surface. It is not damaging in itself, but it is direct evidence that water is passing through the wall.
Can chimney repair wait until spring?
It can, but a winter of freeze-thaw acting on an opening will generally enlarge the job and the cost. The repairs that stay small are the ones done before the first hard freeze.
What is a chimney chase cover?
On a factory-built chimney enclosed in a framed chase, the chase cover is the metal top that serves the same purpose a masonry crown does. Galvanized covers rust through and pond water, and replacing one with stainless is a common repair.
Does homeowners insurance cover chimney damage?
Policies commonly cover sudden events such as storm or lightning damage while excluding gradual deterioration and lack of maintenance. Documentation from an inspection helps establish which category a given problem falls into.
How long does masonry repair take?
A crown repair or targeted tuckpointing is often a one-day job. Larger rebuilds take longer and depend on weather, since mortar has to cure in suitable conditions. We give you the scope and timeline with the price.
Published August 12, 2026