Screw Piling: Piled Underpin For Subsiding House

THE CHALLENGE

This project was very unique, as it was our first screw piling job. The supplier of the “Digga” screw driver & piles was kind enough to deliver them, and give an induction on how the process works.

What made this project more challenging than a typical screw piling job was the fact it was an underpin: securing and rectifying a failed foundation (causing subsidence) by driving piles very close to the existing concrete, and installing a bracket to lift the building back to where it should sit.

WHAT WE DID

Piling

We began with excavating to reveal the pre-existing foundation in eight positions, creating enough space to accommodate the piles and brackets. We then drove each of the eight piles to a depth of four metres each, achieving set refusal. This proved tricky at first, as the drill needed to sit extremely close to the house’s brickwork, but became much easier once the first pile had set.

Steel Ring Beam

As this is an underpin, there was no ring beam or metal reinforcement necessary. Once the piles had been driven, a bracket was installed on top with two threaded bars and nuts that, once tightened, secured the existing footing and bored its weight on the piles.

Concrete

Once the brackets were tightened and the foundation secured, the excavated sections were shuttered and backfilled. We employed Rhino Concrete for this job, as it required installation via wheelbarrows. Grade C35 concrete was installed quickly, with a tidy finish on each of the eight underpins.

THE OUTCOME

Before Rhino was involved, this house suffered from serious subsidence, likely due to being underpinned poorly before. Now, after just three days on site, this property is sat on secure foundations back in its original position.

If you have a similar problem, get in touch with us via phone or email, we would be delighted to hear from you.

Phone: 0161 706 0365 | Email: enquiries@rhinopiling.co.uk