London child centre uses Celcon Thin-Joint

Contractor Balfour Beatty has made substantial savings on a GBP6.4 million Child Development Centre in Hackney, East London by using the Celcon Thin-Joint System from H+H UK

The project comprised two L-shaped buildings in a '69' layout with a central courtyard.

One building is two stories high with glass curtain walling, the other is four stories with solid, Thin-Jointed aircrete walls using Celcon Plus blocks 200mm thick.

The two buildings take up the whole of the site.

The original specification for the four-storey building was dense block externally with a render finish.

Balfour Beatty project manager Steve Penwill had used Celcon blocks with Thin-Joint technology on an extension to his home and had been pleased with the results, so he decided to look at the system for this project.

The solid wall was finished with insulated render on the exterior and dry-lined on the inside.

This was the first major project on which Balfour Beatty had used the Thin-Joint System.

H+H helped with the development of the design, advised on acoustic solutions and produced U-value calculations.

An excellent U-value of 0.30 W/mK was achieved.

Detailed advice was given on the use of bed joint reinforcement that both reduced the amount of reinforcement needed and enabled the number of windposts to be reduced, resulting in a significant reduction in costs.

H+H also provided advice on waste minimisation and the recycling of aircrete block off cuts.

By accepting that buildings settle and move and concrete constructions such as blockwork can create their own movement joints that are not critical structurally, the engineers' design of the blockwork allowed any movement to be hidden behind internal and external finishes.

This also enabled the structural engineers to 'value engineer' the wall - to save costs without compromising performance.

Bed joint reinforcement was used in certain areas, such as above and below windows.

Despite the expense of this reinforcement, if used correctly, it reduces the need for windposts and so cuts costs significantly.

The use of an insulated render also allowed the structural engineers to design out a significant number of wind posts that would otherwise have been necessary to provide lateral support.

The Celcon Thin-Joint System enabled the building to be built faster and to a better quality, allowing follow-on trades to start work sooner in a weatherproof environment, while retaining the flexibility of on-site construction.

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