How is spalling linked to the Periodic Structural Inspection?
The PSI engineer must record signs of structural deterioration, including spalling concrete and corrosion of steel, assess their seriousness and recommend remedial actions. Where spalling is observed, the engineer must carry out simple tests such as tapping in other areas. BCA's standard report template treats localised spalling under 300 mm as a minor structural defect and spalling over 300 mm as a structural defect.
From the RRD Field Guide, checked against the sources cited in Concrete Spalling in Singapore: Causes, Risks, Repair Methods and Who Must Fix It. General information, not advice for your project.
The fuller picture
Spalling concrete is concrete cover cracking and breaking away because the steel reinforcement inside has corroded, usually after carbonation or chlorides destroy the steel's natural protection. Small patches can be repaired by removing loose concrete, cleaning and priming the steel and patching with polymer-modified mortar. Extensive spalling, beams, columns or cantilevers need a Professional Engineer. Owners repair inside HDB flats; MCSTs repair common property.