Building 1000, Lakeside North Harbour, Portsmouth

Perega was instructed by Avison Young to conduct an initial visual survey to the rooftop plant rooms which were constructed with RAAC. The main structure of Building 1000, built in the 1970s, utilised a traditional reinforced concrete construction. The inspection ascertained that the two plant rooms, including the roof, external wall cladding and internal partitions, were all of RAAC construction. For safety in the short term, we recommended temporary propping at regular points, plus anywhere planks had been cut for service ducts, or where there was spalling.

We then carried out further investigations, including a laser scan of the soffit to establish the level of deflection of the RAAC roof panels, this highlighted a high number of defects related to the RAAC panels including: Water ingress to roof and wall panels; Excessive deflection of roof panels; Services passing through roof and wall panels without additional support; Significant cracking and spalling of roof and wall panels; Insufficient bearing length of roof panels; Exposed reinforcement to roof and wall panels. The long-term solution included the replacement of damaged RAAC panels with a lightweight cladding, and remedial strengthening works to wall and roof panels where required, due to damage and to overcome insufficient bearing length.