Stair Tread Restoration at the Basilica of Our Lady Immaculate
January 14, 2020
Heritage Brick and Stone completed remedial restoration work on the monumental exterior staircase at the Basilica of Our Lady Immaculate in Guelph, Ontario.
Located at the head of Macdonell Street, the Basilica is one of Guelph’s most recognizable landmarks. Construction began in 1876, and the church was dedicated in 1888. Its twin towers were completed in 1926. The building is an exceptional example of High Victorian Gothic Revival architecture and was designated a National Historic Site in 1990.
Existing Stair Construction
The Basilica had recently undergone extensive interior and exterior restoration when Heritage Brick and Stone was retained to address deterioration affecting the lower section of its main exterior staircase.
The staircase consisted of precision-cut natural sandstone treads installed over a concrete block foundation. Each tread incorporated a raised lip at the rear, helping protect the horizontal mortar joint between adjacent stones from direct wear and water exposure.
Despite these design considerations, the bottom course of sandstone had deteriorated more rapidly than the upper steps. The relatively soft stone was particularly vulnerable to weather, moisture and exposure to winter road salt from the street below.
Selecting a Durable Replacement
The damaged sandstone treads required replacement, but the new units also needed to blend with the remaining natural stone.
Texture- and colour-matched precast concrete treads were selected to provide greater durability in this highly exposed location. The replacement units were manufactured to closely reproduce the appearance and dimensions of the existing sandstone.
Removing and replacing the lowest treads presented a significant technical challenge. The staircase was constructed as a series of overlapping units, meaning the lower stones could not be removed without carefully managing the weight and position of the surrounding treads.
Controlled Removal
The mortar joints surrounding each damaged tread were carefully saw-cut to separate the unit from the neighbouring stones. This reduced the amount of force transferred into the surrounding sandstone during removal.
Because the existing stone was relatively soft, Heritage Brick and Stone fabricated custom steel corner protectors for use around the tread edges. These protected vulnerable surfaces while power tools and lifting equipment were being used.
A vacuum lifting system was then employed to remove the treads. The equipment created suction through a large rubber gasket placed on the surface of each unit, allowing the stones to be lifted without drilling holes or wrapping them with straps.
This method provided controlled handling while minimizing the risk of damage to the remaining masonry.
Installation and Joint Finishing
The deteriorated treads were removed and replaced systematically, one unit at a time. Each new tread was positioned to within approximately 1/32 of an inch, maintaining consistent alignment across the staircase.
Once installation was complete, the joints between the treads were reinstated and tooled to match the surrounding masonry. Careful attention to joint width, profile and finish allowed the new work to integrate with the existing staircase.
Project Outcome
The completed restoration preserved the architectural character of the Basilica’s main entrance while improving durability at the most exposed section of the staircase.
By combining controlled removal procedures, specialized lifting equipment and carefully matched replacement materials, Heritage Brick and Stone delivered a precise and visually compatible repair suited to one of Guelph’s most significant landmarks.
