It is a known and sadly avoidable fact that dirty chimneys can cause chimney fires, which damage structures, destroy homes and injure or kill people.
Not all chimney fires burn explosively and therefore are not noisy and dramatic enough to be detected by neighbours or passersby. Slow-burning chimney fires, starved of enough air or fuel to be as dramatic or visible, still reach very high temperatures and can cause as much damage to the chimney structure and nearby combustible materials. With proper care, chimney fires are entirely preventable and your ProSweep engineer will recommend an ideal cleaning schedule to ensure your chimney’s safe upkeep. In addition to keeping your chimney clean there are a few other things you can do to prevent chimney fires:
- Use seasoned woods only (dryness is more important than the type of wood used)
- Build smaller, hotter fires that burn more completely and produce less smoke
- Avoid burning cardboard boxes, paper, rubbish or Christmas trees; these can spark a chimney fire
Chimney fires burn at about 2000′ F that in masonry chimneys can melt the mortar, crack tiles, cause liners to collapse and damage the outer masonry material. Most often, tiles crack and mortar is displaced, which provides a route for flames to reach the timbers of the house. It is also possible for enough heat to be conducted through a perfectly sound chimney and ignite nearby combustibles.
In Pre-fabricated, or metal lined chimneys, damage to these systems can still occur, usually in the form of buckled or warped seams and joints. When pre-fabricated or metal chimney liners are damaged by fire, they should no longer be used and must be replaced.
Causes of Chimney Fires
Solid fuel stoves and fireplaces are designed to safely contain and burn fuel, providing heat for your home. The chimneys that serve them have the job of expelling the exhaust fumes and substances given off from the burning fuel.
As these substances rise up the chimney and cool down, condensation occurs and forms a residue that sticks to the chimney. Usually black or brown in appearance, it is highly combustible and in sufficient quantities can catch alight.
Certain conditions encourage the problem; restricted air supply, unseasoned wood and cold chimney temperatures (especially external wall chimneys) are all factors that can accelerate the buildup of flammable residues.
How to tell if you have suffered a chimney fire
Without proper inspection, it’s difficult to be certain your chimney has suffered fire damage, there are a few signs a professional chimney sweep looks for:
- Puffy residue / creosote, with rainbow coloured streaks, that has expanded beyond its normal form
- Warped metal of the damper, metal smoke chamber, connector pipe or factory-built metal chimney
- Cracked or collapsed flue tiles, or tiles with large chunks missing
- Discoloured and distorted rain cap / flue
- Creosote flakes on the roof or ground
- Damaged roofing material
- Cracks in masonry
- Evidence of smoke escaping through mortar joints of masonry or tile liners
What to do if you have a chimney fire
- Call the fire brigade – 999
- If you have, a stove then shut all air vents and flue dampers to reduce the chimney fire’s oxygen supply
- If you have an open fire then gently splash water on it to extinguish the fire
- Move flammable materials, furniture, ornaments away from the fireplace
- If you have an open fire then (as long as there is no risk to you) block the fireplace opening with something non combustible
- Feel the chimneybreast throughout the house, especially those on upper floors – if it is getting hot then move furniture away from it
- Do not pour water on the fire if you have a stove, shut the door
- Do not pour salt on the fire – this can create chlorine gas that is damaging to the chimney and toxic if it gets into the room
- Ensure that the fire brigade can access the loft space
- In severe cases where there is deemed to be a risk of the fire spreading to the roof use a hose to wet down the roof near the chimney but not the chimney itself
- Point a fire extinguisher into the fireplace or wood stove
- Close the glass doors on the fireplace
- Close the air inlets on the wood stove
- Monitor the exterior chimney temperature throughout the house for at least 3 hours after the fire is out
After a chimney fire has occurred, do not try to re-light any appliances. Call prosweep and we will assess any damage caused, advise the likely cause of the fire and where possible make the chimney safe to use again.