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Cracked unstable parapet walls repaired and secured

Client:	Kingston University
Location:	Surrey
Approved Installer:	ASRS
Reference No:	PR227

On the Campus of Kingston University in Surrey, the parapet walls on the west and south west elevations were displaying extensive horizontal cracking and consequent lateral movement. Caused by moisture expansion of the clay bricks, normal thermal activity and the lack of any expansion joints, a reliable stabilisation solution was required to secure the parapets and avoid any possible masonry collapse.

The two and three storey flat roof adjoined faculty buildings, with 9" thick solid parapets, were built around the end of the 19th century as part of the Technical College and later housed the Kingston School of Art. Project engineers, Watts Group PLC, working for the main contractor, Walter Lilly Construction, specified Helifix repair products to secure the parapets.

The Helifix repair scheme, carried out by Approved Installer ASRS, involved bonding double stainless steel HeliBars into the mortar beds at three different levels of the parapet walls across the entire front elevation of all the buildings. These formed masonry beams which reinforced and tied the masonry while also stitching cracks. Combined with the 300m of HeliBar, fully grouted 1.2m long CemTies were installed vertically down through the parapets either side of every upper floor window, extending a minimum of 200mm past the window heads. To prevent future problems, new vertical movement joints, filled with flexible mastic and secured horizontally with moveable DryFix ties, were cut in all panels of masonry longer than 20m.

The non-disruptive and fully concealed Helifix repairs were completed quickly and with minimal disruption to every day campus life, to restore full structural integrity to the parapet walls and provide an economical and engineered alternative to taking down and rebuilding.