Handy tips to keep your chimney safe and clean

July 28, 2015

Where there's fire, there's smoke — and when it's in your fireplace, you'll eventually have a chimney that needs a clean sweep. Chimney fires occur when creosote, a highly combustible residue created by burning wood, ignites. The resulting flames are hotter than the wood in your fireplace and the hot sparks that burst from the chimney could set your home on fire.

Handy tips to keep your chimney safe and clean

1. To prevent chimney fires

  • Have your chimney cleaned regularly by a professional chimney sweep. Cleaning chimneys is difficult, dangerous work that requires special brushes and equipment tailored to fit the precise measurements of your fireplace flue.
  • However, you can and should clean out the ashes in your fireplace when they start piling up.
  • Shovel the ashes into a metal container with a tight-fitting lid — never a paper bag — and store it away from any combustible materials (including a wooden deck) before final disposal.
  • The frequency of chimney cleaning will depend on how much you use your fireplace. At the least, an annual inspection is needed.

2. To inspect a chimney yourself

  • You need to be in good shape and not mind climbing on the roof. Use a tall ladder to gain access to the roof and check that the tiles are not wet and slippery.
  • With the aid of a powerful torchlight, check the chimney openings both from the hearth and from the roof.
  • On the roof, you'll have to remove any spark arrester or chimney cap before you start.
  • Look for obvious obstructions like bird nests. This is important even if all you have is a gas-log fireplace.
  • While gas burns more cleanly than wood, a gas fireplace must be inspected for proper venting to keep odourless, poisonous carbon monoxide out of your home.
  • Check the extent of creosote build-up. The creosote will be black or brown and could vary from a dripping tar-like substance to a shiny hardened mass. The highest concentration of creosote usually occurs in the top one-third of the chimney.

3. Look for indications of a past chimney fire

  • Chimney fires, which roar hot until the energy source is spent or extinguished, sometimes occur without anyone realising it. Such fires can weaken the mortar, crack the tile lining of the chimney or even cause the lining to collapse. Any of those factors mean that heat from subsequent fires could reach and ignite combustible parts of the house, such as the wooden framing.
  • Signs of a chimney fire include puffy creosote with rainbow-coloured streaks, warped metal on the damper or metal smoke chamber, cracked or missing flue tiles, creosote flakes or chunks on the roof, and cracks in the exterior masonry.
  • Inspect the outside of your chimney to make sure there are no cracks that could allow water to seep in.
  • In very cold areas, changes in temperature will cause water that leaks in to freeze and thaw, which can cause mortar to crumble.

4. To find a chimney sweep

  • Check the Yellow Pages.
  • Make sure that the company you choose carries business liability insurance in the event of accidents.

5. To cut down on creosote build-up

  • Only burn wood that's been dried for six months to a year.
  • Freshly cut wood has a higher moisture content than seasoned wood, which results in a smokier fire.
  • Hardwoods, such as eucalyptus, burn more slowly and with a steadier flame than softwoods, such as pine, which cause faster creosote build-up.
  • Never burn painted or chemically treated wood.
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