Chimney Fires/Relining 

Chimney fires are not a normal occurrence but a sudden unexpected event and normally covered by insurance for the repairs . In fact the less frequent the better! A chimney fire is a fire that burnt up the inside walls of the flue, or chimney. It is very similar to what I imagine a jet engine sounds like. There is lots of raw fuel lining a round chamber, an inlet and outlet, and heat from a wood-burning fireplace or wood stove down below. This really sets up a rather ideal scenario for high temperatures and out-of-control burning! Few flues are able to come through a chimney fire unscathed. There is no such thing as a "friendly" chimney fire that will safely clean out your flue. It can have a roar like a freight train, or be so quite you don't know you're having one. It will usually crack's your flue liner and/or chimney and can spread to the structure of the house.

  • dirty chimneys cause fires
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What causes Chimney to Fires Start?

Chimney Fires start when regular usage of a fireplace or wood stove results in build up of a highly flammable buildup called class 3 along the inside walls of the flue, or the inside of the chimney. Class 3 creosote can be black or brown in color. It can be crusty and flaky…tar-like, drippy and sticky…or shiny and hardened. Class 3 will catch fire under the right conditions and cause a chimney fire . THC will need to look at your chimney because all instances of fire and chimney construction are different and that way we can decide what the best path of resolution for repair of your chimney.THC installs chimney liners for all type of fireplaces and venting appliance sun lined chimneys and chimney fire damaged or faulty built flues. THC relines where chimney fires have occurred and damaged the terra cotta flue tile.Relining after a chimney fire is normally covered by homeowners insurance and we can work with you and your insurance company to restore your chimney to better than before the damage occurred. Chimney fires burn can burn as hot as 2100° at that high temperature terra cotta cracks.

Chimney fires are the result of fires being burnt to small and from that is where class 3 develops. When the fire is out the residue left as the picture shows I is puffed up and light and fluffy.


“Puffy” or “honey combed” creosote is what's left after fire has burned out or was put out.

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 Discolored and/or distorted rain cap

Heat-damaged TV antenna attached to the chimney 

Creosote flakes and pieces found on the roof or ground Roofing material damaged from hot creosote

Cracks in exterior masonry from the 

Evidence of smoke escaping through mortar joints of masonry or tile liners 

Depending on the situation, you may need to have your old liners removed and a new liner installed, or just have a new liner system installed or an entire chimney rebuilt. No matter the situation THC will take care the repairs for you no matter how unique you want to ensure that it is repaired and THC has over 35+ years making sure that you and your family are safe. Contact THC today!

Here are more examples of class 3 creosote showing what to be on the lookout in your chimney. Class 3 can't be brushed off and has to have one of several clashing cleaning methods preformed to remove it. The further you get away from where your fire is burning the more chance you have of forming class 3, so if you see it down in living area like the firebox you are going find allot up near top and need to call THC.


Gas and Oil Appliance Linings

THC often gets calls from customers asking does their gas logs and gas appliances need to be lined or relined. For the most of the calls the answer is yes. Knowing that each day, without showing any signs, acid produced by your gas appliance may be eating away at the inside of your chimney. Having your chimney inspected each year as called for by the National Fire Protection Association.

A thorough annual inspection of your chimney, as recommended by the National Fire Protection Association you can know if to your chimney is in good working order or not. You can then take the appropriate steps to correct the problems. But allot do not realize that all vented gas appliances require a chimney for proper venting of the gases produced from normal operation of that appliance from water heaters to gas furnaces. Although gas appliances don't produce visible soot for the most part. Gas appliances produce highly corrosive gases. These gases are highly acidic and will destroy your masonry chimney without you seeing any external symptoms until the repair of damage has become greater than if you would have had your chimney inspected and problems found earlier. Today's more efficient furnaces get most of the heat from combustion to add in heating your home. Because of that there is less heat to use for proper draft. Heat plays a large roll in proper draft of the venting system. Gas appliances are sold under the impression that they are clean burning throughout the country. Under perfect conditions when appliance and vent are perfectly matched for the most part that's true. Air used for combustion carries acid in the form of chloride within it some picked up from everyday cleaners from cleaning products in and around your home. That air mixes with moisture and hydrochloric acid is formed and from that point other acids may be picked up in your vent pipe or flue. When your venting system is not properly matched to your appliance a tremendous amount of moisture forms in your flue and that acidic liquid will deteriorate your flue. Once the lining begins to break down it's only a matter of time before your chimney is blocked and your home is invaded with carbon monoxide.

deteriorated flue


*Paint peeling off walls
*White staining on outside of chimney
*stains on ceiling*mortar that's eroded on chimney
*crumbling bricks
*Damp patches on interior walls or exterior walls and or peeling wall paper

These examples are due to the high moisture laden gases getting out into living area due to unlined or improperly lined chimneys.


If the chimney was properly lined the conditions for this to take place would not have been there. An oil furnace needs a chimney liner. The purpose of any chimney liner, or flue, is to keep the smoke, fumes and toxic gases from penetrating the chimney mortar and entering the living space. The fuel used in an oil furnace creates an oil mist. If this by-product is not correctly vented, the substance will build up on surfaces around the home; the process is called “puff-back.” Cleaning up the mist can be costly. Also, a chimney liner protects the framing and walls of the structure from extreme heat and prevents fire. New high efficiency oil-fired appliances require smaller flue sizes than older units. Where an old unit may require an eight-inch flue, the replacement unit’s installation instructions may call for a five-inch flue. This is a 60% reduction in flue size. Couple that with lower flue gas temperatures of new units and the flue size becomes much more critical to the proper operation of the present day oil-fired appliance. In cold, over sized masonry chimneys, the less-hot flue gases of modern appliances quickly expand and cool even more. Draft is drastically reduced because it depends upon the buoyancy of the hot flue gases. The cooler the gases become, the slower they move up the flue and the more the draft is reduced. This will reduce an appliance’s efficiency and increase fuel consumption. The longer the flue gasses remain in the flue, the greater the risk of leakage into the home.

removing lining

The Importance of Draft

A proper heating appliance/venting system match will help ensure adequate draft in the system. Draft is important for a number of reasons.Inadequate draft can reduce the efficiency and safety of the appliance.Complete combustion requires oxygen – combustion of one cubic foot of natural gas requires more than 10 cubic feet of air to provide sufficient oxygen. Adequate draft ensures that enough air is pulled into the appliance for complete combustion. Chimneys that are unlined or lined with Terracotta materials are must often found to be unable to perform their intended function in Portis head present condition, and according to the National Fire Protection they should not be used until corrected. Make sure that your gas or oil furnace was installed according to the manufacturer’s installation instructions and the National Fire Protection Association Standards. The two most important NFPA standards that apply to gas appliances are NFPA 54 and NFPA 211. Your appliance’s installation manual should give you all the necessary information.Dangerous carbon monoxide gas can be forced into your home through open mortar joints, cracked flue liners and flues blocked by debris. Deterioration of the flue liner can occur when venting oil fired appliances or gas furnaces. Chemical compounds such as sulfur residues from the oil and chlorides from the laundry area, when combined with water, form highly aggressive acids capable of causing considerable damage to flue tiles in masonry chimneys.The purpose of any chimney liner, or flue, is to keep the smoke, fumes and toxic gases from penetrating the chimney mortar and entering the living space. How can these problems be solved? Installing a UL Listed liner system , properly sized and properly installed is the most important and easiest way to prevent these problems.A properly sized chimney lining system will insure correct draft by preventing the flue gases from expanding and cooling more than they should. Properly-sizing a chimney liner will greatly reduce condensation within the venting system. The hot and buoyant flue gases will remain hot, exit the flue quicker, cool less and be much less likely to condense on the chimney or liner walls. By using a watertight flue liner any condensation that might form is contained within the liner, thereby avoiding further damage to the chimney from freeze/thaw cycles and corrosion from the highly acidic condensation.

A Final Point Concerning Equipment Performance and Efficiency

A new chimney lining system for your oil-fired or gas-fired appliance can improve its performance and increase the life of your chimney. Increased oil burner efficiency means less oil is required to heat your home. This reduces your fuel bill. Call THC to insure everything about your heating system is correct.