House built next to busy road with piled foundations

Project Overview

The site is on the corner of a busy junction through the heart of a picturesque village. Both roads are in constant use by very large, heavy farming machinery. The biggest challenge during construction was the likelihood of collapse caused by of excavating a 3.5m hole next to a road. For this reason contiguous piled foundations were used to support the excavation.

This basement was a technical challenge for many reasons. If you have a similar project, take a look below as to how we carried this out, or contact us for more information.

Project Details

Description

Categories:
Client: Langton Homes Ltd.
Location: Ashley, Market Harborough
Surface Area: 85 square meters
Completed: 2013
Architect: BRP Architects
Link: Visit project
Click here to see plans of the basement
Click here to see sections of the pile foundations

Stage 1

Piled foundations & excavation

To ensure the road would not collapse into the basement, the side adjacent to the road was supported using contiguous piles. 300mm holes were drilled to 10m deep, filled with steel reinforcing and concrete. All these individual columns of concrete were set right next to the previous, creating a continuous barrier of concrete columns.

The top of each pile was cleared away and linked with all of the others using steel reinforcing and concreted. This pile cap beam supported the top whilst undisturbed ground below the excavation supports the bottom of the columns.

The excavation could then begin, extending all the way to the face of the piles. Perforated drain then was laid around the perimeter and linked to a sump allowing the site to be constantly de-watered. A layer of concrete was laid to give the site a dry, clean base on which to build the basement.

Site next to roadGround leveledHard standing made for large piling equipmentPiled foundations drilledConcrete and steel cast in piled foundationsPile heads joinedPile tops joined with steel and concrete to create pile cap beamExcavation safely taking place next to roadOnce complete the excavation exposed the top third of the piled foundations and the cap beam
Piled foundations and excavation lined & dewateredExcavation completeBase layer cast to allow clean dry work spaceBase layer cast to allow clean dry work spaceBase shuttering beginningBasement slab steelCreating upstands to link walls and floorCreating upstands to link walls and floor across the piled foundationsInternal ground water sump cast and reinforced"Kicker" being constructedSlab ready for concreteConcrete pumped in to basement slabBasement slab and kicker completeExternal wall shuttering and steelWalls cast in two halvesShutters supported to take the load of concreteWalls ready for concreteTop of piled foundations forms the top of the structural wallSecond half of walls being constructedWalls finished & stripped off

Stage 2

Basement construction

With the piled foundations and excavation completed, the sides were matted and drained the work could begin on the slab. The perimeter was set out with preformed aluminium shutters set to the correct height of the slab. A sump was installed for the internal waterproofing and steel reinforcing laid.

The steel had two layers sticking up through the floor to link the walls and floor together. Finally, a small upstand was created, known as a kicker, this creates better waterproofing. The kicker is the bottom 150mm of the walls but is cast at the same time as the floor.

Once the slab had been cast in concrete and all shuttering removed, the walls were constructed. The external face of the shuttering was erected and supported and steel reinforcing installed within the walls, connected to the bars coming through from the base. The internal shutters are then erected and supported fully to bear the weight of the concrete.

Stage 3

Waterproofing & finishing

This basement has two independent waterproofing systems

Type A – Barrier Protection

A cementitious slurry was applied to all external faces and linked with the perimeter drain and sump that was installed as part of stage 1.

Waterproofing materials supplied by Koster UK

Type C – Cavity Drained Protection

A cavity drainage membrane (CDM) was installed internally to all external walls and the floor and linked to the ground water sump. Within the sump, two pumps and a high-water alarm were installed.

Waterproofing materials supplied by Triton Systems

External walls coated with type A cementitious slurryExternal walls coated with type A cementitious slurryBasement backfilled, external sump left accessible for future maintenanceExternal viewMain room in basementStaircase to basement barBasement wine cellar

Take a look at some of our similar previous retrofit basement projects. Or click below to contact us and get a quote

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