Chimneys and stacks have only one function: dispersing flue gas into the atmosphere. In the process of
fulfilling that function, they are exposed to harsh environments, both inside and outside. Flue gas, with its
abrasive and corrosive characteristics, can damage the structural materials of the chimney or liner.
Climatic conditions, ranging from high winds to extreme cold, place extreme stress on the structure itself.
From inside -Mortar or flashing can deteriorate with age and be in need of repair or replacement. It is useful to inspect the ceiling after a long period of rain, as the source of a leak is easier to trace. If stains are found, try tracing the source of the stain as it is not always directly overhead.
Check inside the roof space for signs of dampness. Water can penetrate the roof surface and travel between the roof and ceiling level before finding its way through the ceiling.
Water staining on the ceiling or on the chimney breast walls will indicate dampness getting through. Dampness here indicates problems with the flashings causing the water to penetrate and run down the walls. If there is water staining inside a room near a fireplace lower down the walls, then the problem could be due to the flue and the fireplace being completely sealed.
Dampness inside the home can sometimes indicate problems associated with the chimney stacks.
Outside at ground level -Outside, check the roof by inspecting at ground level. If chimney pots are broken, cracked or missing they are easy to spot. Only the edges of the flaunching can be seen, but check for deterioration or cracks in the mortar holding the pots in position.
Use binoculars to scan the surface around the stack as carefully as possible, from all angles - front, back and sides where applicable. Look for mortar missing from between bricks on the stack itself.
Check that the stack is still in a vertical position and not leaning. Look out for bulges in masonry or blown rendering or pebbledash.
At the roof level -If you are using a ladder, always make sure it is set up correctly and long enough - at least 3 rungs above the gutter. Always work with someone standing near by when you are working at a height. See our Ladder Users Guide for details on how to use a ladder correctly and safely.
Once at the roof level, only access the surface of the roof using a roof ladder. This is a purpose built ladder that has wheels to allow you to push it up the sloping roof without dislodging or damaging the slates. When the wheels reach the top of the roof ridge, by turning the ladder over a hook securely lodges on the ridge. Roof ladders can be hired.
Otherwise, there are wheel and hook sections available to buy which fit onto conventional ladders. If you are going to be working on the house, perhaps a scaffold tower would be worth hiring.The chimney stacks could be too high to work on from a roof ladder and there is chimney scaffolding available which is specially designed for this type of work. This type of scaffolding is also useful for more difficult jobs like removing and replacing pots on tall chimneys.