Chimney stacks are commonly found on older buildings and help to punctuate rooflines and provide visual interest. For the purpose of keeping open the choice of fuel, houses should be provided with Class I flues and chimneys. 

Traditionally, chimneys play an important architectural role in the composition of houses, and should therefore be of suitably massive construction. This will also enable them to contribute to the structure of the building. 

They should be positioned on the ridge line of the roof, centrally on a gable end or against an outside wall, and should have pots. In the case of small dwellings without fireplaces, gas flues or soil and vent outlets can be combined into chimney structures. 

On flank gable ends, chimney stacks should be flush with the wall or else project sufficiently that the stack appears strong enough to stand unsupported.