After several redesigns, the engineers settled on a system of 12 piles and a reinforced slab. It was a bit of a saga getting to that point, because although we are next to a pond, there was nevertheless more water in the trial borehole than the experts expected.
The initial plan by the contractors was to auger the piles, to avoid using a pile driver near an old building. However, this was vulnerable to water inflows, which proved excessive, which would have made it hard to be sure the concrete would set properly.
So we were advised to switch to steel-cased piles, with the first three metres augered. With hammered piling starting three metres below ground, it was hoped that the vibrations in the old house would be reduced. This proved the case, though we checked the house carefully every hour or so to make sure there was no damage. Continue reading “Foundations”