Piled Basement; Nottinghill, London W11

before piling nottinghill

Project brief:

As main Piling contractor on this project, we were required to provide a Contiguous Piled Retaining Wall around the perimeter of the property. The property is a five storey end terraced house in the heart of Nottinghill. The side access to the garden was 2.5m wide, which restricted the size of Piling rig we could use onsite.

The basement on this project will be two levels, with the first level as living quarters, and the second as plant and storage rooms. This meant that the retained depth changed where we stepped down for the double basement, so our Contiguous Pile depth ranged from 8.0 – 15.0m. And as we are a smaller company, with a hands on attitude, our engineer was onsite to over see most of the Piling works. This enabled us to sort out any problems quickly, keeping the programme within time scale.

The whole house is to be put on a transfer slab extending the basement, beyond the footprint of the house. This required us to install temporary Bearing Piles to take the load of the house while the basement is being excavated. There are also a number of internal and external Tension Piles and internal Compression Piles to take loadings of 200kn at sub basement level.

Scope of works:

*Site welfare and Health and Saftey set out by Main contractor.

*Mobilise T5000 Auger Rig and 300mm dia solid stem augers to reach design depth.

*Steel and safe area for making cages was set up.

*Dumper for concrete with a chute.

*Lifting frame with 110v winch to safely lower cages for Internal Piles with minimum headroom of 2.3m.

*Complete all external Contiguous piles and Tension Piles.

*Install Contiguous Piles to form sub basement, which will join up with deeper external piles.

*Install Temporary Piles which will support the transfer slab while Sub basement is being excavated.

*Install Bearing Piles with a design depth to take 200kn.

*Clear site and demobilise T5000 Auger Rig and all other equipment.

Engineer checking dimensions

On our first visit to site our engineer checks access and the centre lines of piles, so we can decide which Rig would be most efficient onsite.

T5000 Internal contig wall

T5000 Auger Rig with outriggers and 300mm dia lead flight with a cutting head for London clay and mudstone.

Restricted access to contig wall piles in basement

All the walls had been underpinned by the main contractor, the Contiguous Piled wall had to continue between the remaining walls supporting the house which proved to be very challenging. This was particularly challenging underneath the stairs to the front door, where we had to install 4 Piles at our minimum working headroom 2.25m, which meant boring and casting 2 Piles a day.

lifting frame and 110v winch

All of the steel reinforcement for the Contiguous Piled Retaining Wall had 6H16 @ 2.2m long in a H8 helical – 200mm O/D (overall diameter) and pitch of 150mm (distance between helix). The design depth for these piles was 15.0m, so we had to connect and lower 10 cages in each open bore before casting the pile. Our custom winch and lifting frame has a SWL of 500kg and makes this job very safe.

Sub basement Contg wall

Contiguous Piles installed, cut and broken down ready for capping beam.

Dumper with concrete chute

Advanced Mini Piling Systems operative, with a concrete dumper, is far more efficient than using wheel barrows. Also a lot cleaner than using a concrete pump, which requires a lot of water to clean, which becomes difficult in winter.

capping beam on contig piled retaining wall

As you can see from the photo the reinforcement has not been cut down, saving the main contractor time and money when casting the capping beam. We care about what we do, and we work with the client, not for them.

finished retaining wall

Part of the finished retaining wall to the basement, underneath the bay window, also acting as a fire escape.

Get in Touch