How often do you look at your chimney? It is easy to forget it is there, especially if you don’t have an open fire, but a simple inspection could pinpoint potential problems and prevent them turning into major repair and reconstruction jobs.

If the stack is leaning, this will be obvious from ground level. You may also be able to detect other problems, such as large cracks in the stack, just by looking up. However, small fissures, deteriorating flaunching, or loose chimney pots would only be visible at close range on the roof. Contact a roofing contractor to carry out this kind of detailed inspection, as it is dangerous to work on the roof if you are not professionally trained and do not have specialist equipment. For safety reasons, UK legislation requires that most chimney repairs should be carried out using scaffolding. You could save money by having chimney and other roofing repairs done at the same time.

There are several reasons why chimney stacks start to lean. Often, unsuitable modern mortar has been used to repair damage to the pointing. Porous 19th century bricks require re-pointing with lime mortar. A hard cement-rich mortar could make the bricks loosen more quickly, causing instability. The weather is another damaging factor. The prevailing wind can dry out the mortar on one side of the stack, making it shrink. On the other side of the stack, the moisture in the mortar will make it expand, and the tension that results causes the stack to lean. Working chimneys risk being damaged internally by hot gases rising through the flue, while unused chimneys may be endangered structurally if the chimney breast has been taken out. If you notice any leaning, you should always seek professional advice as to whether the chimney needs to be removed or reconstructed.

Damp causes all kinds of problems. Moisture can enter through small cracks in the mortar, so the brickwork may need to be re-pointed. In working flues, damp can be caused by condensation. Allowing wood to dry out before burning can reduce condensation, or just install a flue liner. Cap a redundant flue to stop rainwater coming in, but keep air moving through the flue to let any moisture evaporate. Water can also enter the stack via faults in the flashing – the metal seal between the roof and the bottom of the stack. The flashing needs to be a good height, so if water is coming through, you may need to add more. Loose flashing should be re-fastened to the roof and any damaged strips replaced with new flashing.

Flaunching – the protective layer of mortar around the top of the stack that keeps the pots secure – is susceptible to frost damage. Cracked and crumbling flaunching should be replaced by a roofing contractor. Secure unstable pots, as these pose a danger to the public.

Many roofing companies are experienced in dealing with chimney repairs, so don’t leave it too late before seeking professional help and advice.