Cellar & Basement Construction, Excavation and Conversion Services

Performance Foundations provides expert services for basement construction, including piling, retaining walls, underpinning and all associated works.

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Performance Foundations provides a range of basement construction services for residential and commercial projects

Basements are an excellent way of adding space to your home, and making the most of your plot of land. They can provide additional living space, a home cinema, gym or office, a garage, extra room for any number of other uses. They also broaden the appeal of your home and increase the market value.

There are similar advantages for commercial property, including garaging, work space and storage. Basements are a genuine asset for all kinds of buildings.

What work will Performance Foundations do?

As experienced basement building contractors, we will supply clear and detailed quotations for all of the work that is needed to renovate, extend or build a completely new basement.

Alternatively, we will quote only for those parts of the work you want us to undertake. We have a long track record of working successfully with other professionals and contractors. We pride ourselves on working with a personal touch and we are committed to delivering what our clients want.

What type of basement do you want?

Depending on your site, your aim may be to improve an existing basement or cellar. Alternatively, your plans may be for a completely new basement to be created under your property. Single level basements are the most common type of project we undertake, but there are options on dual level basements, and basements which extend outside of the footprint of an existing building to run under garden and patio areas.

Performance Foundations are piling contractors who support all types of basement project on homes of all sizes as well as commercial properties.

Basement projects begin with the site being cleared to allow access to existing foundations.

For any enlargement work on an old basement or for a new basement, soil needs to be excavated by either mechanical or manual means. If access is possible, a conveyor can be used to bring soil out of the area, but on certain sites manual removal by barrows is the only option.

By excavating below ground, support for the structure above ground is weakened.

Underpinning strengthens and stabilises the ground through the use of piling and grouting. Piling involves boring holes in various ways, and filling the cavities with concrete to provide a strong, permanent support for walls, blocks and beams. 

What are the different types of piling?   

As specialist piling contractors we are experts in using different types of pile foundations to provide effective structural support for different types of construction and different site conditions. Piling rigs are used on site to drive drilling machinery.

CFA piles and auger bored piling

An auger is like a giant corkscrew which drills down into the earth and excavates soil through the screw action. We frequently use CFA (continuous flight auger) piling in confined spaces. CFA operation is continuous, making this a highly efficient piling technique.

Mini piling

Where space is limited we use our specialist mini piling rigs to drive smaller piles into the ground. By using the right number of mini piles, we create a strong and stable structure for your basement and above ground building. 

Rotary piling

Rotary piling is used for larger piles. It works by a large auger screw being lifted from the cavity every five or so turns, with the soil, rubble and other material being removed before the auger is repeatedly lowered for further excavation.

Bottom driven piling

For poor ground conditions where deep foundations are not possible, we use bottom driven piling. Steel lining tubes are pile driven by a drop hammer striking a dry mix concrete plug. The tubes are in-filled using workable high strength concrete or grout.

Find out more about our expert underpinning and piling services.

Retaining walls

Basement developments need retaining walls to create clear space for the basement, and to form a permanent building structure. There are a range of different approaches to retaining walls which are largely site specific.

Contiguous piled walls

Contiguous piled walls are constructed by drilling piles close together to form a very strong retaining and supporting structure. We use them for safe excavation and ground stabilisation, especially on sites with limited access.

Reinforced concrete retaining walls

Where site access is less restricted we use reinforced concrete to build retaining walls, particularly for sloping sites which need excavation. Concrete is poured into cavities created by temporary shuttering (such as plywood) which is removed after the concrete is set.

Sheet piling walls

A further option is the use of interlocking steel sheets to form retaining walls. The preformed sheets are driven into the ground and together form a robust wall. They are particularly suitable for large sites and quick installation.

See more types of retaining walls, including gravity retaining walls, cantilever retaining walls and anchored retaining walls.

See more retaining walls

Waterproofing basements

Basements can be blighted by damp. Moisture collection and humidity can usually be addressed by improving ventilation, but the problem is more serious if there is a weakness in the basement structure. When we build basements we use different types of waterproofing depending on the water risk to your basement. There are three principal types of waterproofing:

  • Barrier (eg cement coating)
  • Integral (fully bonded membrane)
  • Drained (drainage built into the structure)

Basement floors and walls

The most common approach to basement floors is to use poured concrete. Some projects have involved using steel grids as a base material for floors, as well as block and beam construction.

Further options include installing underfloor heating and drainage work for basement toilets and washing facilities.

Basement walls can be finished with concrete, brickwork or pre-formed panels with the same finishing options available as for the rest of your premises. 

Next steps for your basement project

We work on basement construction with homeowners, national builders, architects and civil engineers.

Get in touch now to discuss your basement project