The subject building was a substantial purpose built library constructed in the mid-1930s of brick on a concrete foundation.
Visible cracking and lifting movement noted to the window openings to the top floor front and two side elevations. A total of 20 windows.
The external brickwork soldier course formed a flat arch above the window openings. The flat arches were built on a 50mm × 50mm mild steel angle that was found to be heavily corroding and delaminating.
Severe corrosion of the embedded mild steel support angles and its resulting expansion had caused severe distress to the adjacent brickwork.
The internal brickwork was being supported by an independent concrete lintel.
AWT completed a remedial scheme, introducing bed joint reinforcement beaming, fenestration lintel repair, grout tie injection and resin bonded ties.
1. Bed joint reinforcement beaming: The introduction of two rows of twin cord reinforcement, forming a composite deep masonry beam – as indicated with red double dotted lines on our proposal images.
2. Fenestration lintel repair: To the underside of the fenestration openings head, we drilled for, and injected, grouted 8mm helical stainless steel pins through the brick arch, passing into the line of the composite deep masonry beam installed within the existing masonry – as indicated with green parallel lines on our proposal images.
3. Resin bonded ties: Within the area of the beaming we drilled for (wherever possible to the centre of a brick), and resin bonded, new 6mm stainless steel remedial ties (four per square metre) above window openings, then re-pointed disturbed areas only with coloured sand and cement mortar.
After the proposed reinforcing works had been completed the windows were removed (by others) to enable the removal of the mild steel angles and making good of the brickwork.