The process of building a basement

Initial consultation

You will sit down with your basement specialist or architect. You will discuss your needs for the proposed project. You will then be given an indication of the costs involved. You will also be offered a quotation for the structural and fit-out work.

Design and planning

A full survey of the property is carried out. A design for the proposed basement is then created. Once a design has been agreed, the planning permission application is submitted. This should take approximately eight weeks.

While you wait for planning approval, a party wall surveyor is appointed. Your basement specialist or architect does this. The surveyor will serve notice on the neighbours. They will also obtain the party wall award. Once the Party Wall award and planning permission are obtained, your specialist contacts you. You will receive an idea of the timeframe for each phase of the project. You will also get the final time for completion.

Building

Work on the basement is started by digging and removing any soil. Any underpinning works are carried out. Reinforced concrete and timber or steel beams are erected as required. They support the structure of the existing house. This follows the guidance of a structural engineer. The basement excavation will involve supporting the existing foundations and the internal loadbearing walls. It will also involve supporting floors. Any concrete pads that may be supporting an existing extension need support too.

This will then be followed by waterproofing the structure. Drain runs and existing manholes are reconfigured. This ensures that you are left with a waterproof shell. It is ready for the next stage of fitting the basement out.

Fit-out

The fit-out starts with the insulated, screed-covered floor. This then takes carpet, wood flooring or tiles. After that come the electrics, the plumbing, and the first and second fix items. These include joinery, doors and painted finishes. All of them have to comply with Building Regulations. Then the lighting scheme, and finally the furniture.

Every square foot of living space is at a premium in London. Digging down is often the only direction left. NU Projects excavates, converts and builds basements under occupied London houses. We coordinate the planning and the party wall process. We also coordinate the structural design, all in the same contract.

Before you appoint anybody, read the ten checks worth making. To talk about a specific property, tell us about it. To price the work, use the cost calculator.