The following problems are some of the most commonly encountered problems with chimneys, stove flues and open fireplaces. Many of these problems are the result of inefficient, poorly maintained or deteriorating chimneys.

The fire is not drawing properly

This is usually the result of a cold (flues take a little time to warm up and work correctly) or an obstructed flue or it may even be because of an insufficient height compared to the ridge of the roof or an nearby building. Sometimes double glazing and very efficient draught excluders around doors, etc, may prevent an adequate flow of air for the fire to work correctly. If no other work has taken place and the fire suddenly does not draw properly you should have the flue checked for obstructions and probably swept at the same time.

The fire creates a large amount of soot

This usually means you have an inefficient flue. This may be because the flue is not the right diameter for the fire or stove, or may it not be satisfactorily insulated so that the fumes do not rise fast enough and therefore create soot deposits on the inside. Excessive soot and tar can be a considerable fire hazard, particularly if the chimney structure has deteriorated or where, on the older house for example, the floor joists have been built into the stack,. In this case the whole house can be at risk. Again, the first step would be to have the chimney swept and ask a qualified chimney installer to check the flue – possibly by carrying out a smoke test to make sure that the fumes will rise swiftly and efficiently.

Mortar or brick is falling into the fireplace

Bits of brick or mortar falling down the flue indicate a serious deterioration in the chimney structure. Such deterioration normally occurs from the inside of the flue but if there is any indication of weakness on the outside of the chimney then attention is obviously necessary. You should use an experienced builder to check the structure of the chimney, preferably one that is used to working on chimney construction and will use the correct materials,  and not a general jobbing builder who is more prone to cut corners.

There are fumes or smoke in the room

These may not be easily detected on closed appliances such as stoves although if, with an open fire, the chimney smokes back into the room they are then obvious. Fumes contain carbon monoxide and are dangerous (Carbon Monoxide fumes from a blocked chimney may be fatal). Where there are leaks in the chimney the fumes can find their way into upstairs rooms and attics. Sometimes a tell-tale smoke stain around the edge of a carpet shows the presence of fumes. The presence of Carbon Monoxide can be checked for by buying a CO tester (either a strip or an alarm that resembles a smoke detector).

The chimney breast feels hot

This means that the chimney has deteriorated and may be dangerous. A hot wall in the room above the fireplace may be a similar symptom. If stains also appear on the chimney breast this is a sign that tar or acids have condensed and are eating into the chimney mortar and brickwork. As with the comments about mortar falling into the chimney, you should use an experienced builder to check the structure of the chimney, preferably one that is used to working on chimneys and not a general jobbing builder. It may be possible to line the existing flue with a new flue liner rather than have to knock out the whole chimney stack and have it rebuilt.

And finally

If you think that you have problems with a chimney in your house – always get it checked out especially if the problem suddenly happens, the risk of fire or carbon monoxide poisoning is very real.


Carbon Monoxide produces the following effects on people exposed to the concentrations shown below :

Concentration of CO in air Inhalation time and toxic developed
50 parts per million (ppm) This is a safe level as specified by the Health and Safety Executive
200 PPM Slight headache within 2-3 hours
400 PPM Frontal headache within 1-2 hours, becoming widespread in 3 hours
800 PPM Dizziness, nausea, convulsions within 45 minutes, insensible in 2 hours

Carbon Monoxide poisons you by entering the lungs via the normal breathing and displaces oxygen from the bloodstream. Interruption of the normal supply of oxygen can result in the symptoms shown above and even in death.

Please note that the information in the above table is for a healthy adult. Persons suffering from heart or respiratory problems, infants and small children, unborn children, expectant mothers and pets can be affected by CO poisoning more quickly than others in the household and may be the first to show symptoms. If you have ANY doubts you should open a window or door to let the fumes escape, leave the room and get the appliance checked.