Guide to Conversion of Traditional Buildings

Preface to standards 3.18, 3.19 and 2.20 for combustion appliances

These three standards are concerned with features such as chimneys, flue pipes, the size and design of flues, the location of flue terminals and the relationship of chimneys, flue pipes and appliances to combustible materials. Standards 3.18 and 3.20 are standards that must be met in a conversion, while Standard 3.19 is one that must be met as close to the requirement in so far as is reasonably practicable. Therefore, in attempting to alter these existing features to comply with the standards, there is a risk that the works may impact on the historic character and cultural significance of a building.

Original chimneys are important features of historic buildings, and chimneystacks and pots are essential to the character of the roofscape of both individual buildings and groups of buildings. These features should always be retained, and reinstated or (where necessary) repaired using traditional methods. Over the life of a building, original chimney pots are often replaced with pots of modern design which detract from the character of the roofscape. Broken or unsuitable chimney pots should be replaced with ones that match the original or are of a local pattern. Redundant chimneys are sometimes demolished to save on maintenance costs or because they have developed structural problems. However, their contribution to a building’s character is such that efforts should be made to retain and repair them, perhaps finding a new use in venting rooms, appliances or roof spaces.

Where possible, the opportunity should be taken to rebuild previously altered or demolished chimneys using traditional materials that match the original if this will restore the appearance and character of the building. Sometimes chimneys have been rebuilt using brick with a rendered finish. Render tends to have a short life in exposed rooftops, and the condition should be addressed as a priority for public safety and to stop water ingress to the building. The opportunity should be taken to rebuild the chimney in its original materials although it is important to carry out research to ensure that any new build or repair work accurately reflects the original design and materials. Before rebuilding original chimneys, a review of similar properties in the area and consultation with any surviving photographs and drawings should inform their restoration. It should be noted that many harled or rubble Scottish buildings had brick chimneys so it shouldn’t be presumed that these are a replacement.

The installation of new flues for modern appliances will be a common requirement and must be designed in sympathy with the character of the building. Modern flues installed either within the building or fixed to an external wall can damage historic fabric and impact on a building’s traditional character. Similarly, poorly sited modern flue terminals projecting above the roofline can be unsightly and not in sympathy with the historic nature of the building.