Our expertise lends itself to creation of basements below existing buildings or adjacent to them. We can undertake a complete package to form the “structural shell” ready to handover to a builder to fit out the new basement to create a habitable area. The structural shell can include the waterproofing.

Support of the building above

We often find that the safest and surest approach is to support the existing building at ground floor level and then excavate below to form the basement. Support of the building above is usually carried out by use of sacrificial stools as described for structural openings to create a series of beams or a slab at ground floor level. This will span onto piles or underpinning previously installed as appropriate to the project.

Earth retaining structure around the building perimeter

This can be contiguous piles, underpinning or a combination of the two systems. Maximum space is gained with use of reinforced ‘L’ Shaped underpinning following the profile of the wall above. Sometimes it is possible to provide the same plan area as the building at ground floor level but slightly off-set so that contiguous piles can be used to create the support. This often proves to be the most economic route.

Excavation and Formation of the Structural Box

Use of conveyors is often the best means of removing material from site. For the concrete lining wall we have used water-proof concrete to avoid the necessity to apply an independent water-proofing system. When the building is particularly vulnerable to moisture ingress then a double system can be used such as waterproof concrete and a cavity drain system.

Clients feed back leads us to believe that it is difficult to find a contractor prepared to come into a building to install a single new lift shaft or modify an existing one. The work is very intricate and involved but limited in its scope. We are always keen to undertake other work in the building at the same time but we are equally willing to install the lift shaft as a “oneoff” project.

New Lift Pits

The techniques described for basements are equally applicable to the creation of a new lift pit. We are sometimes asked to form a shaft capable of accommodating an hydraulic lift ram some 450mm diameter. Depending on the access conditions this can be achieved using a piling technique or an open site underpinning technique. In the latter case a shaft is hand dug and a sealed steel casing is offered into the ground. The casing is then concreted into position with adequate provision to prevent floatation.