Fireplaces and flues
Our 1910s house has a brick chimney with no liner. Can we use it?
Not until a camera has checked the chimney. We inspect, line, rebuild and retire the unlined brick chimneys of 1900s to 1920s Portland houses, where heat and flue gases reach the mortar joints because no clay tile was set inside.
Updated
What an unlined brick chimney is and how it vents
An unlined brick chimney is a flue made of nothing but brick and mortar: no clay tile, no metal liner, just the inside faces of the bricks, sometimes coated with a thin mortar parging when the mason finished the job.
Smoke, heat and acidic flue gases run straight up the brick, and the mortar joints are the only thing between them and the framing. Over a century the joints erode from inside, the parging drops off in sheets, and gases find a wall cavity or the flue next door.
Roughly 27 percent of Portland housing units date from 1939 or earlier by Census count, and many of the 1900s to 1920s chimneys among them went up with no tile at all, some a single brick thick. A fireplace flue and a furnace flue commonly share one of these stacks.
How to tell what you have
You can usually spot an unlined brick chimney from the hearth and the sidewalk.
- Look up past the damper with a flashlight: brick courses and mortar joints running out of sight mean no liner, while smooth tile faces mean a lined flue.
- From the street, a flat mortar top with a bare rectangular hole and no clay tile showing above the crown points to an unlined flue.
- Mortar sand and flakes of parging on the smoke shelf or in the cleanout, with no tile chips among them, are the inside of the joints coming down.
- A slender stack where the flue hole takes up nearly the whole width of the brick is a single-wythe chimney, one brick between fire and siding.
What you will find in Portland homes
These are the unlined brick chimneys we find in Portland houses.
| Type or model | Era | Notes |
|---|---|---|
| Single-wythe unlined stack | Older brick houses | One brick thick, the joints the only barrier; the brick above the roof goes soft and leans first, and a liner needs room it may not have. |
| Double-wythe unlined stack with parging | Older brick houses | Two bricks thick with a mortar wash inside when new; the parging flakes and piles on the shelf, and the camera finds open joints behind it. |
| Shared stack, fireplace and furnace flues side by side | Older brick houses | A thin brick wall between the flues lets gases cross, so smoke turns up in the basement or furnace exhaust at the hearth; each flue gets its own liner. |
| Unlined flue with a wood stove or insert vented into it | Retrofit, any decade | Creosote packs the joints where a connector or an unlined insert dumps into the open flue; the first fix is a liner run to the appliance outlet. |
What goes wrong and what fixes it
Each unlined chimney problem below is paired with its fix.
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A pre-1930 house with a chimney nobody has scoped, or a sale closing on one
A Level 2 inspection, the camera run up the whole flue, the images and a plain yes or no Chimney Inspection, from $129
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Open joints, missing parging and heat reaching framing behind the brick
A stainless liner matched to the appliance, with insulation where the flue needs it Chimney Liner Installation, from $1999
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Soft, spalled or leaning brick above the roof on a single-wythe stack
The stack taken down to sound brick and rebuilt with a tile, or shortened to the roofline Chimney Rebuild, from $2499
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Mortar washing out of the outside joints on a stack that is bare inside too
Joints repointed on the outside, with the camera deciding whether the inside needs a liner Tuckpointing and Masonry Repair, from $449
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Creosote baked into the joints behind a stove connector or an unlined insert
The flue swept to bare brick, then the appliance put on its own liner before it burns again Chimney Sweep, from $249
What the camera sees inside an unlined brick chimney
A Level 2 camera run grades an unlined flue by four things: eroded joints, fallen parging, cracks into the next flue, and offsets that limit the liner.
- Mortar joints eroded back into the wall, leaving a groove between every brick course where heat and flue gases now sit.
- Parging that has lifted or fallen away, with bare brick behind it and a pile of flakes on the smoke shelf.
- Light from the next flue, which means the brick wall between them is cracked or missing.
- Offsets, corbels and a narrowing where the stack steps around a joist, which decide what size liner will pass.
Liner, rebuild or retire: the three ways out
A sound stack gets a liner, a failing one is rebuilt from the roofline, and a flue with nothing to serve is retired; the camera decides.
| Path | When it fits | What you end up with |
|---|---|---|
| Stainless liner | The stack above the roof is sound and the flue is wide enough for a liner sized to the appliance | A continuous metal flue inside the old brick, insulated so it draws, matched to the appliance |
| Rebuild from the roofline | The stack above the roof is soft, spalled or leaning, or the flue is too tight for a liner | New brick with a tile or liner inside, built to the old height on the stack below |
| Retire the flue | The fireplace or furnace is not coming back, or the stack is a quake hazard not worth saving | A capped and sealed flue, or the brick taken down to the roofline and the hole roofed over |
Earthquakes and home sales, the two times an unlined brick chimney gets attention
An unlined 1910s chimney is also an unreinforced one, and unreinforced brick chimneys can collapse or break in an earthquake, the tall slender stacks most of all.
The State of Oregon puts the odds of a magnitude 7.1 or larger Cascadia quake in the next fifty years at about 37 percent. Strapping the stack, cutting it to the roofline or swapping the top for a metal chimney each reduce the falling hazard, and none touch the joints inside.
At a sale, the national chimney standard asks for a Level 2 inspection, and on a pre-1930 Portland house the first thing the camera settles is whether there is a tile. A buyer who learns that before closing can price the liner into the offer.
Unlined brick chimney questions
Can we use an unlined brick chimney at all, or does it need a liner first?
Keep it cold until a camera inspection has graded it. An unlined flue with tight joints can pass, and one with open joints needs a liner before the next fire. The joints are the whole question: open, eroded or leaking joints put heat and gases against framing, and no amount of sweeping changes that.
How can I tell if my old brick chimney is unlined without a camera?
Look up past the open damper with a bright flashlight. Brick courses and mortar joints running up out of sight mean no liner; smooth tile faces with widely spaced joints mean a lined flue. Outside, a flat mortar top with no tile standing above it points the same way.
Will a stainless liner fit inside an unlined brick chimney from the 1910s?
Often, but not always at the size an open fireplace wants. A liner is sized to the appliance it serves, and a slender single-wythe stack may only pass a liner sized for a stove or an insert. The camera run measures the offsets and the tightest point, and the quote names the liner size and what it can serve.
Is an unlined brick chimney a problem when buying or selling a Portland house?
It is a known cost rather than a deal breaker, as long as it is found before closing. The standard recommends a Level 2 camera inspection at a sale, the report says whether the flue is lined and usable, and a liner or a rebuild can be priced into the negotiation.
What happens to an unlined brick chimney in an earthquake?
It cracks at the roofline and can fall onto the roof or through it. The brick is unreinforced and the joints are already weak from a century of flue gases, and tall slender stacks are the ones that go first. Strapping, shortening the stack or a metal upper chimney reduce the hazard without removing it.
Related pages
Unlined brick chimney calls near you
Unlined brick chimney work has taken us to Aloha, Cornelius, Happy Valley and the rest of the metro, and the posted price is the same at every address.
Other fireplace and flue types
Ready to book a sweep?
Call with what the fireplace is doing, or text a photo of the opening and one of the chimney top, and we will name the service and its posted price before we come out.