How to clean your chimney and flue

Where there’s smoke there’s a chance of fire, but diligent maintenance of your chimney will keep both smoke and fire in their proper places. Examine a chimney yearly for the safety and security of your family and home. Chimneys get dirty from use, bricks become loose with age and weather, and flues crack and become blocked.

Chimney cleaning

A properly maintained furnace or boiler burns cleanly with little soot accumulation. But if you use your fireplace frequently, clean the chimney at least once a year-more often if you burn softwood. Creosote, a sticky black residue created by burning wood, is carried by the smoke and deposited in the chimney. It reduces the ability of the flue to draw off smoke and, because it is flammable, can cause a chimney fire. Chimney fires often spread to the roof or adjacent houses.

Chimney with two flues
Cleaning a chimney is a tedious, dirty job and can be dangerous, as you must climb onto the roof. It is safer to call in a professional chimney sweep. He’ll block off all flue openings into the house, work the soot down the chimney, and vacuum it away. If you do clean your own chimney, follow the same procedure.

Most stove stores sell special long handled wire brushes in sizes to fit any flue. You can measure your flue by reaching up the hearth beyond the damper of a fireplace or into the flue opening of a wood stove. If in doubt about the size, buy a brush that is too large and trim its bristles to fit. Sweep out each flue thoroughly with one of these. Take any metal stovepipe down and brush it out with a round wire brush made for that size pipe.

When all interior surfaces of stovepipe and chimney flues have been brushed thoroughly, remove the coverings taped around each flue opening and vacuum them diligently. Work from the highest opening down so that any soot dislodged will fall to lower openings still closed. Repairing brickwork If your chimney passes through the house, inspect it wherever it is visible-usually in the attic. Have a helper shine a strong light up the chimney or burn damp rags in the fireplace while you wait in the attic. If any light or smoke comes through, there’s a leak. Repair leaks with mortar. Replace missing or badly broken bricks .

For greater safety, new chimneys are built with ceramic flue linings. If your chimney is more than 50 years old, it may not have a flue lining and so maybe unsafe. Hire a mason to either add a lining or to lower a prefabricated metal chimney inside your unlined chimney.