In terms of building regulations, it does not state that you necessarily have to have your chimney lined. However, there are consequences to deciding to not have it lined especially if it has not been checked to ensure that it is safe and meets certain requirements. Generally the following list should be adhered to in order to ensure that your chimney is safe:
- It can be regularly swept
- It can be proven to be sound using a smoke test procedure
- It has the suitable dimensions for a stove
- A stove fitter can properly connect to the chimney in a way that will fit all building regulations
- The stove can draw in the ways which the manufacturer guarantees
- All building regulations surrounding it are properly met
If this list cannot be properly met then there are a number of possible consequences that could occur, putting you and your home in danger.
If it cannot be properly swept and cleaned then it is likely that a chimney fire will start. This would be far less likely and much more easily contained if your chimney was properly lined as it would be contained within the inner metal flue tube.
If your chimney is not proven to be sound using the smoke test procedure then the smoke and carbon dioxide created by fire can easily travel into your home or surrounding homes and can kill you. Having your chimney lined ensures that the smoke properly exits your property in a contained manner.
As everyone knows, hot air rises but what happens when the chimney is not hot enough to allow the smoke to rise and exit to property? If your chimney flue contains cold and non-smooth surfaces the smoke will eventually drop and seep into your property bleeding through the walls and damaging any wallpaper/paint you have. If the smoke slows down too much it will dampen your flames and mean that your fuel is not burning properly which in turn creates creosote and will eventually cause a chimney fire.