By Johnathan Mason, Ace Chimney Service.
Older houses are the reason chimney liners exist. Before liners became standard practice, plenty of chimneys were built as bare brick shafts, and many of those are still standing and still in use. If your house predates the middle of the last century, it is worth knowing what is inside the stack before you light the first fire of the season. This comes up regularly in Bull Valley, where a lot of the housing stock has real age to it.
What does a chimney liner do?
A liner is the smooth interior channel that carries combustion gases from the appliance to the outside. It does three things at once: it keeps intense heat away from the surrounding framing, it protects the masonry from corrosive acidic byproducts, and it gives the flue a correctly sized, smooth path so the chimney drafts properly. Without one, the brick and mortar are doing all three jobs, and mortar was never designed for it.
The three kinds you are likely to have
Unlined. Bare masonry with no liner at all. Heat passes into the surrounding structure more readily, and mortar joints erode from flue gases until gaps open into the chimney chase. Common in genuinely old construction.
Clay tile. Square or round terracotta sections stacked inside the masonry. This is the most common liner in older homes and it works well — until it does not. Clay is rigid and it does not tolerate sudden heat well. A chimney fire, or decades of freeze and thaw with water in the joints, cracks the tiles.
Stainless steel. A continuous metal liner sized to the appliance, usually insulated. This is what a modern reline installs and what we fit when a clay flue has failed.
Signs the liner has failed
- Pieces of terracotta or clay shards in the firebox or on the smoke shelf.
- Sand-like gritty debris accumulating where it did not before.
- A draft that has become sluggish or reversed without another explanation.
- Smoke or smoke odor appearing in a room the fireplace does not open onto.
- Any use of the fireplace after a known chimney fire, however small it seemed.
- An appliance replaced with a different size or fuel without the flue being resized.
Why cracked tiles are not cosmetic
A crack in a flue tile is a direct path for heat and combustion gases into the space between the liner and the masonry, which in many houses is right next to structural framing. That is the mechanism behind a large share of house fires that start at the chimney. It is also how carbon monoxide reaches living space from a flue that vents a furnace or water heater. This is the one finding where we will tell you plainly not to use the fireplace until it is resolved.
Finding out in Bull Valley
You cannot judge a liner from the firebox or the top. It takes a camera scan, which is part of a Level 2 chimney inspection. If the liner has failed, chimney relining is the repair, and the starting price is published on our pricing page. Ace Chimney Service, 29 years, insured and bonded, price up front, serving Bull Valley and McHenry County seven days a week, 7 AM to 7 PM. Call (815) 320-0883.
Frequently asked questions
How do I know if my chimney is lined?
Sometimes you can see a tile edge looking up from the firebox or down from the top, but a camera scan is the reliable way, and it is the only way to judge condition rather than presence.
Is an unlined chimney illegal to use?
Codes have required liners on new construction for a long time, and existing chimneys are generally allowed to remain. Allowed and safe are not the same thing, which is why it gets inspected before use.
How long does a stainless liner last?
A quality stainless liner sized correctly and installed properly is a long-term component, and better grades carry substantial manufacturer warranties. Annual inspection is what keeps that lifespan realistic.
Can cracked clay tiles be repaired instead of replaced?
Some cast-in-place and sealant repair systems exist for limited damage. Widespread cracking is usually better solved with a stainless liner.
How long does a relining job take?
Most straightforward relines are completed in a day. Height, offsets in the flue, and difficult access can extend that.
Does a liner need to match the appliance size?
Yes, and this is often overlooked. An oversized flue lets gases cool too fast, which hurts draft and produces more creosote. Sizing is part of the job.
Does a wood stove insert need its own liner?
An insert should be connected with a correctly sized liner running the full height of the chimney. Venting an insert into an open oversized flue is a common and avoidable error.
Do you serve Bull Valley and nearby towns?
Yes. We are based in Crystal Lake and serve Bull Valley, Woodstock, Prairie Grove, McHenry, and the wider county seven days a week.
Published August 19, 2026