Tower repair and viewing platform:

Inverness Castle North Tower

Inverness · 2017

Our role: Principal contractor
Client: The Highland Council
Value: £0.5m to £1m
Programme: 2016 to 2017, 36 weeks
Scope: Sandstone repair and replacement, cornice and string course renewal, descaling, lime repointing, lead capping and cornice coverings, new sandstone access ramp and steps, spiral stair and glass viewing enclosure, internal upgrades, hard and soft landscaping

Inverness Castle stands on a mound above the River Ness, built in red sandstone in 1836 to designs by William Burn, with the North Block added in 1848. The Highland Council appointed us as principal contractor to repair the North Tower and carry out the building and landscaping works that turned it into a public viewing platform for High Life Highland, with new access, a shop and a stair to the roof, while the Sheriff Court continued to operate in the rest of the building.

Inverness Castle North Tower, Castle Hill, Inverness — photograph 1

Inverness Castle North Tower, Castle Hill, Inverness — photograph 2

Inverness Castle North Tower, Castle Hill, Inverness — photograph 3

Inverness Castle North Tower, Castle Hill, Inverness — photograph 4

Inverness Castle North Tower, Castle Hill, Inverness — photograph 5

The challenge

The soft red sandstone of the tower had decayed badly. The large curved cornice and string course bands were eroded, the face of the stone was scaling, and the whole tower had been pointed in hard cement, which was trapping moisture and accelerating the loss of stone. The project also had to deliver a working visitor attraction: a steel spiral stair and a glass enclosure had to be lifted onto the tower roof in the middle of the city, the internal rooms had to be brought up to current fire and access standards, and a new access ramp and path had to be built up the steep castle mound, all without disrupting a live court building.

Our solution

Defective stonework on the North Tower was repaired or replaced in matching red sandstone, including new sections of the large curved cornice and string courses. Where the face was friable but replacement could be avoided, the stone was carefully descaled back to a sound surface. All cement pointing was raked out and the tower was repointed in a traditional lime mortar so the sandstone can breathe and the rate of decay is slowed. The tower capping and the cornice details were given new lead coverings to throw water clear of the replaced stone. The spiral stair and the glass viewing enclosure were craned into position over a series of early Sunday mornings to keep the city centre and the court unaffected. Inside, the rooms were rewired, the heating overhauled, and new sprinklers, fire doors, ceilings, stairs and accessible toilets installed to meet building control and fire requirements, with noise and dust controlled throughout because the court remained in use. Outside, a new public access ramp and steps were built in stugged red sandstone ashlar with sandstone copes and metal handrails to match the existing walls, finished in Caithness stone slabs. The grounds were relandscaped with a resin bound path and purpose-made railings up the winding approach, the battlement terrace was re-graded and slabbed in Caithness stone with interpretation plaques, and the remaining areas were turfed.