Case Studies - Kindergarten extension to Bury Grammar School: Top driven steel piles

During the last three months of 2006 we installed the piles, ground beams and floor slab to a new kindergarten extension at Bury Grammar School, Bury.

For three months from September through to November 2006 we undertook one of the largest contracts we had carried out. Working for and in conjunction with Priory Loft Conversions we installed the piles, reinforced ground beams and floor slab to the Kindergarten Extension at Bury Grammar School.

Installation of the piles began on the second week of September 2006. The piles on the Kindergarten extension were a 177mm diameter steel tube with a thick wall of 10mm driven to depths varying across the site from 5metres to over 9metres. All 246no. piles were successfully installed very quickly over a period of 10 days by one of our top dive rigs.

Excavation of the ground quickly began once all the piles had been driven. In order to keep costs down trenches were dug below pile platform level to form the ground beams and pile caps required. The excavated ground help up very well and therefore any costs involving formwork were very low. The piles could now be cut down to the correct level.

Our groundwork division began to install the reinforced steel cages in early October and began to pump concrete in phases to the ground beam. The ground beams were 600mm x 600mm with T12 links and 4no T20 bars top and bottom. Throughout the remainder of October the ground beams were completed.

Once all of the ground beams were in place the perimeter brickwork for the floor slab was built. Construction of the first phase of the 200mm floor slab began in the middle of November and consisted of a single sheet of B785 mesh to the bottom with additional local reinforcement where required. 

The first phase of the floor slab was poured on the 30th November using a total of 252 cubic metres of concrete to cover the 1295 sqm area. The smaller 387 sqm second phase was completed a week later.