CHIMNEY SWEEP AND HEARTH PROFESSIONAL OF CT MA AND RI
"An ounce of prevention is worth a pound of cure"
Ben Franklin, 1736
Chimney fire causes
When coal soot deposits or wood tar deposits build up to a sufficient level there is the risk of chimney fire. The heat from the fire warms the deposits releasing the combustible volatiles until they ignite. The fire then migrates up the chimney as the burning deposits heat the chimney above.
How to tell if you have a chimney fire - You will often hear a roaring noise* in the chimney, especially with an open fire. Outside masses of smoke will be pouring out of the chimney.
When you start to see flames coming out of the chimney you know that the chimney fire is near it's end.
* many have described, similiar to that of a train
What to do if you have a chimney fire
- 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, in a fireplace, then gently splash water on it to extinguish the fire, never pour water in or on a hot stove.
- 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, in the absence of fireplace doors, with something noncombustible
- Feel the chimney breast throughout the house - if it is getting hot then move furniture away from it
- NEVER pour water on the fire if you have a stove
- NEVER pour salt on the fire - this can create chlorine gas which is damaging to the chimney and toxic if it gets into the room
- 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
Damage caused by chimney fires
Coal soot chimney fires can create temperatures up to 1000 degrees centigrade inside the chimney.
Wood tar chimney fires can create temperatures up to 1200 degrees centigrade inside the chimney.
Clay liners - a chimney fire will often cause clay liners to crack and therefore the chimney will probably need to be relined (you may be able to claim for this under your household fire insurance). Contact us for advice or call your insurance company for specific coverages.
As the chimney heats up during the chimney fire, it expands - this causes plasterwork to crack and even blow off and can cause structural damage to the chimney.
On one chimney fire job I observed the headboard of the bed that was against the chimney breast it had been scorched and the plaster looked like a underground subway map. On another job there had been a wood tar fire to the stone-built chimney. The stones inside the chimney had a glassy sheen as the high temperature inside the chimney had vitrified them!
Worst case scenario chimney fires
Chimney deposits are intumesce and expand when heated. In the worst-case scenario they can expand to the extent that they block the chimney. The chimney fire will then seek oxygen from the nearest available source - usually the stove or fireplace - which means that the fire can come out of the bottom of the chimney.
In extreme cases where the integrity of the top of the chimney is already compromised the top courses of brick can blow off due to the pressures inside the blocked chimney.
Heat from the chimney fire can transfer into joists and weaken them through smoldering and cause them to catch fire. Sparks and debris flying out of the chimney can also set fire to the roof if there are tiles or shingles missing.
Call Jeffrey L. Decker today for all your chimney needs.
Working Together to Protect Your Home and Family