Concrete Cill and Mullion Repairs, Office Conversion, Guildford

The problem

A commercial client had around 50 individual repair areas across spalled cills and mullions on an office building being converted to residential use. The client came to us with repair instructions from a structural engineer who had specified the repair method and products.

The cause

Cills and mullions are exposed to weather on every side and older commercial buildings often have less generous concrete cover, which is why corrosion had progressed across so many separate points rather than staying isolated to one or two areas — the kind of widespread damage that often only comes to light during a full conversion.

What we did

1. Trade co-ordination. The conversion had multiple trades working simultaneously across the building. We had to work and liaise with other contractors throughout to ensure our repairs were carried out safely and in the right sequence.
2. Steel treatment. Exposed reinforcement at every repair area treated with Fosroc Nitoprime Zincrich primer, as specified by the structural engineer.
3. Reinstatement with Fosroc Renderoc. Every repair area rebuilt using Fosroc Renderoc structural repair mortar. The Fosroc specification was chosen by the engineer — we worked to it.

The result

One of our longer concrete repair programmes, running for approximately a month given the scale of the conversion. Working on a live construction site with multiple trades required active co-ordination throughout — not just concrete repair skills but site management and communication.