Retrofitting Traditional Buildings: Chimneys

In our fifth blog in our TBHC Retrofit series, Callum, SCHT Heritage Trainee, takes a look at Chimneys, there importance to traditional buildings and some Retrofit options.

Many traditional Scottish buildings feature chimneys. Chimneys were developed as an effective means of drawing the products of combustion away from the fireplace to the external environment. The main parts of a chimney include the hearth, firebox, flue, cope, and pots:


  • The hearth is the floor of the fireplace, which is normally formed of stone or brick and projects into the room where the fireplace is located.
  • The firebox refers to the area surrounding the fire, where fuel is burned.
  • The chimney flue is the vertical shaft which runs from the firebox up to the top of the chimney, through which the products of combustion pass.
  • The cope is a flat structure formed of slabs or stone, which sits atop the head of the flue. The cope has a larger area than the flue beneath and incorporates drips at its edges. This detail protects the flue from water ingress by shedding water away from the flue.
  • The chimney pots are hollow structures which allow smoke and other products of combustion to pass through them to the external environment. Chimney pots raise the overall chimney height, increasing the chimney’s updraught.

To ensure traditional buildings can operate efficiently, it is important that chimneys are kept in good condition and that any problems are identified and resolved quickly. The installation of specific retrofit measures to chimneys can increase the overall energy efficiency of a property.


Retrofit Solutions for Chimneys

Chimney Cowls

Chimney cowls are a capping device which can be installed on top of a chimney pot. A chimney cowl provides protection to the pot below and prevents rainwater from entering the chimney structure. Chimney cowls are commonly formed from clay or aluminium, with many modern chimney cowls being ventilated to ensure air can still circulate within the flue, preventing a buildup of damp, stale air. The installation of a chimney cowl can also boost the energy efficiency of a building, as they help to improve the airflow through the chimney, causing fuel to burn more efficiently and at higher temperatures. The type of cowl you require will depend on whether the connected flue is still in use.


Chimney Balloons

Retrofit solutions can be used to minimise chimney draughts whilst still maintaining adequate ventilation. One solution is a chimney balloon, an inflatable sack inserted into the chimney flue from the fireplace, then inflated once in position. When inflated the device is shaped to create a small gap which maintains ventilation of the flue. Inflation of the device effectively seals the flue, minimising heat loss. Chimney balloon devices are easily reversible, as they are held in place through friction. There are also solid chimney blocking devices, which work in much the same way as chimney balloons. Whilst effective, chimney balloons or other similar devices must be removed prior to using the chimney.


Flue Linings

Over time, the gases created through burning fuel can cause flue masonry to degrade, which may eventually result in significant damage to the chimney. Damaged chimney flues may negatively affect the energy efficiency of a building as worn flue masonry will fail to retain heat as effectively. Flue linings will not improve the condition of a chimney’s masonry, so a chimney which is in poor condition may need repaired or even rebuilt, before a flue lining can be installed. If masonry requires replacement, you should also consider the embodied energy of replacement sections. To prolong the lifespan of chimney structures and improve their energy efficiency, a retrofit flue lining may be a suitable solution. A flue lining is applied to the inner surface of the flue which prevents harmful gases from attacking the masonry. Flue linings can be poured, tiled or metallic. Whilst flue linings will require professional installation and can be costly, the benefits to the building may be substantial.


Fireplace Draught Excluders

When not in operation, open flues may contribute to draughts within buildings and could be a significant source of air leakage. To minimise the negative impact of chimney flues on energy efficiency, the installation of a high-quality fireplace draught excluder may be beneficial. Fireplace draught excluders are made from a highly insulative material and consist of a square or rectangular section which can be fitted over the fireplace opening when not in use. Certain proprietary fireplace draught excluders incorporate magnetic strips to ensure draught excluders remain securely in position when fitted. When properly installed, fireplace draught excluders can significantly reduce the volume of warm air escaping from a property, boosting its energy efficiency noticeably.

Read our other Retrofit Blogs

Further Information

More information relating to chimneys in traditional buildings, commonly encountered issues and solutions can be found at the following links:

Retrofit Blogs

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