It is true; most chimney damage is actually caused by water. Far more damage is caused by rain than by chimney fires. Not to discount the danger of a chimney fire when it happens, but the rain – especially in the rainy parts of the year can cause serious problems with chimneys.
Whether your chimney is masonry or factory-built, long term water exposure can eventually cause cracks or gaps in chimneys where creosote can accumulate and will increase the risk of a chimney fire or even provide passage for dangerous carbon monoxide gases to enter your living areas of home.
What are the clues to a potential problem? If a factory built chimney then rust stains are one significant clue. These could be on the outside or the inside. If they are in the fireplace then the risk can become even higher – if you see it in the fireplace then it is likely a lot worse up the chimney.
Another clue may be any standing water or where you see water dripping – water anywhere near your home is never a good thing. Your chimney does not like water and neither does any other part of your home – water is their #1 enemy.
Look for bent, damaged or missing flashing. The metal flashing around your masonry or factory built chimney (as well as the caulking as well) are designed to keep water out. They must be intact and in good condition to work well. These can become warped or damaged over time and cause water intrusion and eventual water damage.
If you don’t have a rain cap get one now. If there is not one there is a considerable increase in risk of damage.
If a masonry chimney – consider having waterproofing applied to the outside – a proper material will allow moisture to escape out but prevent it from entering the masonry. Never use any paint or non-vapour permeable water sealer not designed for masonry – as it will make it worse and actually can hasten masonry deterioration!
Call a Certified Chimney Sweep to perform any recommended jobs – the Certified Chimney Sweeps are the top level of the industry’s professional standard.