Atholl Crescent, in the Scottish city of Perth, is in a prominent location and contains a long terrace of architecturally significant Georgian properties that are all Category A listed. Around the pilaster at the junction of two office properties, a bulge had developed in the front walls that required stabilising. As both contain busy offices that could not be closed, it was important that the structural repairs caused minimum disruption to both businesses, as well as leaving the building fabric visibly unaltered.
Constructed with ashlar faced rubble-filled solid walls, the lateral movement of some 50-70mm in the front elevation was identified after a period of heavy rain. Delamination resulting from water ingress was determined as the cause of the problem and had to be resolved before the structural repairs could take place. Having established that all internal joists were sound and that there was no separation between internal and external walls, SDM in conjunction with Helifix devised a suitable repair specification.
Lateral restraint was provided across the front elevations, especially at the pilaster junction of the two properties, to secure the delaminated masonry. As a Helifix Approved Installer, we installed grouted CemTies to stabilise the rubble-filled walls and the pilaster and HD BowTies which tied the elevation to noggins/dwangs between the first floor joists. On the internal party wall at ground and first floor levels, stainless steel HeliBars were bonded into the mortar beds at three levels and embedded at an angle 500mm into the front elevation. This was done on a room by room basis to minimise disruption.
Once the concealed Helifix repairs had been completed and made good, the pilaster and front elevations were completely stabilised and the aesthetics of these Grade A listed buildings had been fully maintained.