Conservation in action: Holmwood steps

As with many buildings constructed around the same time in Glasgow (including Alexander Thomson’s own house), Holmwood and its front steps were constructed using local Giffnock freestone. The details of the materials used during the construction of Holmwood are largely found in Blackie’s Villa and Cottage Architecture of 1868, including a description from Thomson on the masonry works:

‘The material of all external walls is free-stone, from Giffnock quarries, distant about a mile. It is set as irregularly coarsed rubbble, hammer-dressed on the face; and the joints are pointed with cement, line-drawn and finally painted with white lead. The dressings are tooled: rubbed or polished work have been avoided throughout. A course of Caithness paving-stone is built into the walls to prevent the rise of damp. There is a considerable amount of decoration to columns and piers, and in incised lines and ornament.’

A recent condition survey of Holmwood identified urgent repairs were required to maintain the structural integrity of the plinths and steps, and to prevent further deterioration and saturation to the stonework. We received funding from Historic Environment Scotland to help address some of these issues.

The survey had identified failures to the upper surface of the front entrance steps. With the exception of the bottom step, the steps are bedded into each plinth and rest on a central supporting wall. There is no evidence that the ground around this was made up to offer additional support. Therefore, a likely cause of deterioration is the supporting wall subsiding, which is removing the central support to the steps and thus increasing stress in the centre of each tread.

Interestingly, the final/outermost step is constructed differently. It is T-shaped, locking into the void below rather than into the plinth, and it isn’t indicated on any of Thomson’s published drawings of Holmwood (or on the above perspective in Villa and Cottage Architecture). It is visible, however, in the early 20th-century photographs of the house. This stone step was also causing us concern, as it had moved out of position by 5cm and needed additional support to keep it in place.

Remedial works included removing the stones and treads to enable the dwarf wall to be repaired and to form a new, solid foundation for the outermost step. We then reinstated the stonework, and indents were carried out to the areas that had deteriorated beyond repair.

We also tackled the plinths that were showing obvious signs of deterioration. The photographs below show the heavy staining, blackened stonework and orange lichen that had resulted from the high moisture in the stonework. This is perhaps unsurprising, given the lack of perimeter drainage coupled with an overflow from the roof channelling water on to the surface! The use of cementitious pointing mortar also trapped moisture in the stone and created the ideal conditions for the growth of lichens.

To prevent further erosion of the original stonework in the plinths and the loss of definition, the biological growth has been removed through gentle stone-cleaning methods. The stonework has been re-pointed in a vapour-permeable lime mortar. We’ve also improved the drainage around the base of the plinths, to prevent future saturation to the sandstone. We hope to run a future project to investigate if the roof run-off can be relocated.

The remedial works to the front entrance are now complete, preserving the structural integrity of the steps and plinths, and restoring the aesthetic of the main entrance to the building. It is through your support that we are able to continue essential repairs and maintenance to the buildings we look after, and protect our unique structures such as the ornate detail that can be found in Thomson’s original design at Holmwood.