Bradley subdivision fireplace smoking into the room: the house was pulling harder than the chimney

By Jacob Dove, Friendship Chimney Sweep

What the homeowner described

The house sits in one of the newer Bradley subdivisions off the north side of town, a two-story built in the late 1990s with a masonry-faced wood-burning fireplace in the family room. The owners had replaced the windows, added spray foam at the rim joists and put in a powerful range hood when they remodeled the kitchen. The first fire of the season went fine. The second, lit while dinner was cooking, sent a sheet of smoke out of the firebox and set off two smoke alarms.

They assumed the chimney was blocked. It is a fair guess, and we checked it first: a sweep, a camera run from the smoke chamber to the cap, the damper cycled, the cap screen inspected. The flue was in good shape, with a light first-stage deposit and nothing restricting it [Observed]. So the chimney could move smoke. Something was out-pulling it.

How we proved it was pressure

A chimney drafts because warm flue gas is lighter than the cold air outside. That lift is modest, especially in the first minutes of a fire when the flue is still cold. A house also has exhaust devices: bath fans, a dryer, and in this case a range hood moving several hundred cubic feet of air a minute. Every cubic foot that leaves has to come back in from somewhere. In an older, leaky house it slips in around windows. In a house that has been sealed up, the easiest open path is often the fireplace flue, running the wrong way.

We tested it simply. With a small fire burning and the hood off, smoke went straight up. We turned the hood on high and held a smoke pencil at the firebox opening; within a minute the smoke curled back into the room. We opened a nearby window a few inches and the draft recovered. That is a clear sign of depressurization, not a chimney defect. We also noted the gas water heater and furnace in the basement, because the same pressure that pushes fireplace smoke into a room can pull combustion gases out of an appliance vent, which is a carbon monoxide concern.

What we recommended

For the fireplace itself, the owners now crack a window near the hearth while a fire is burning, keep the range hood off during the first half hour of a fire, and build fires top-down so the flue warms fast. For the house, we recommended that their HVAC contractor evaluate a makeup air provision for the range hood, which many codes require for larger hoods, and that they keep working carbon monoxide alarms on every level. We checked the furnace and water heater vents for backdrafting with the hood running and documented the results for them.

Jacob Dove has seen this pattern for most of his 29 years in the trade, and it gets more common as Bradley homes are updated. Our inspections follow the NFPA 211 standard, and we are Insured & Bonded. Inspection rates are listed on the pricing page, and we are available seven days a week, 7am to 9pm, at (815) 449-4264.

If this sounds like your house: we handle chimney inspection across Kankakee County, and our Bradley page covers what we usually find there. Call (815) 449-4264, 7am to 9pm, any day.

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