chimney repointing at Ulster Folk Museum,

Restoration work was recently completed on six chimneys at Ulster Folk Museum, with a focus on preserving both structural integrity and historical authenticity.

All chimneys were carefully raked out to remove deteriorated mortar before being repointed using Natural Hydraulic Lime (NHL). The original mortar had reached the end of its serviceable life, and replacing it with lime was essential for the long-term health of the masonry. Unlike modern cement-based mortars, lime allows the structure to breathe. This breathability lets trapped moisture evaporate naturally, reducing the risk of internal damp, frost damage, and brick decay. Concrete mortars, by contrast, are dense and rigid — they trap moisture and can force it to escape through the masonry itself, often leading to cracking and accelerated deterioration, particularly in historic buildings.

The existing chimney hunching was also removed and replaced with new lime capping across all stacks. This provides improved weather protection while maintaining compatibility with the original materials.

One chimney was found to be structurally unsafe and had to be carefully dismantled. It was then fully rebuilt using the original bricks, bedded and pointed in lime mortar to retain historic character and ensure appropriate movement and flexibility within the structure.

Following completion, the chimneys were wrapped in hessian for a controlled curing period. This traditional method protects fresh lime work from drying too quickly, allowing it to cure gradually and develop maximum strength.

The result is a sympathetic restoration that protects the chimneys while respecting traditional building methods.