Flues in Chimneys

Modern chimneys are built fully lined with a corrosion-resistant, rectangular, precast concrete flue suitable for any fire. If you have an older chimney, it may have an unlined flue. If there are cracks in the mortar you should have it lined. Seek advice from a professional — they may recommend installing a concrete or metal flue liner compatible with your fuel type.

Unlined Flue
Basic chimney constructed of brick or stone.

Courtesy of © 2007 Dorling Kindersley Limited

Lined Flue
A chimney with a concrete or metal liner in it.

Courtesy of © 2007 Dorling Kindersley Limited

Chimney Caps

Chimney pots provide a decorative finish and raise the top of the chimney above the roof line, where the airflow draws combustion gases out. A chimney cap is often attached to the top to improve ventilation and keep out rain and animals. If any damp problems are associated with a chimney, check that the flashing and pointing are intact, and that a cap has been installed. Different cap designs are used with different fire types, so make sure you have the right cap. If you are opening up an old fireplace, you should enlist professional help to check that the top of the chimney has not been blocked and is fitted with the right type of cap, and that the chimney is in good repair. They may also install or replace a flue liner.

Standard Chimney Cap
If your chimney is well-situated and has no significant downdraft problems, a basic chimney cap will prevent entry of rain, hail, animals and birds.

Pamper Cap
This type of chimney cap can be adjusted to fit most chimney pots. It is designed to prevent downdrafts from blowing smoke and fumes back into the house, and to prevent entry of rain, hail, animals and birds.

Revolving Chimney Cap
Chimney caps that revolve are designed to encourage airflow in chimneys that don't draw air well and are prone to downdrafts.