Protecting the Past: Restoration of Heritage Structure
Twistfix products are often used as part of remedial plans to renovate and restore listed buildings. One such building is Hall Place, a Grade II listed building located in Portsmouth.
Portsmouth, in Hampshire, along with other exposed areas on the south coast such as Dorset and West Sussex, was one of the first regions in which cavity wall structures became widely adopted. Hall Place, which was built in 1796, is the perfect example of an early cavity wall structure in the UK: when a system of repairs and cavity wall tie replacement was proposed for the structure, Twistfix was the first port of call for the contractors, 1st Master Wall Ties.
Hall Place is built using yellow buff bricks, a prestigious material, sourced from nearby in Dorset. Comprising a 9" structural inner wall and a 4.5" outer façade of Flemish bond brickwork known as 'snapped header', the front elevation of Hall Place features a solid parapet wall. Careful inspection showed that the outer leaf of the cavity wall was out of plumb and exhibited a series of undulations between levels; the soldier course lintels had also failed, leading to cracked brickwork above windows.
The leaves of the cavity wall were reconnected, and the soldier course lintels pinned, using Twistfix helical cavity wall ties. As it was essential to maintain the appearance of the façade, our self-tapping cavity wall tie replacements were used: these ties are installed into the smallest possible pilot holes (just 6mm in diameter) which are subsequently filled to make them practically invisible.
Above the window openings, helical bars were installed. This bed joint reinforcement formed a series of deep masonry beams, enabling all vertical loads to be properly distributed on either side of the brickwork, repairing the cracks and preventing any further movement.