Guide to basement construction

Building a basement is an exciting and rewarding project. For the right property it will represent a sound investment, with the value added to the property significantly exceeding the cost of the work. However, you should first consider the following questions:

  1. Will the planner allow changes to the property (especially lightwells)?
  2. If you own a leasehold property, will the freeholder allow the construction works?
  3. Are you prepared for the inconvenience?
  4. Is the timescale acceptable?

Initially, you may wish to consult your local authority. Planners will often deal with matters on the telephone and most have a walk in facility where you can discuss your project on an informal basis. Generally, most houses and ground floor flats are suitable for the addition of a basement (and one easy way to tell is to see if any other houses nearby have basements), but there may occasionally be exceptions.

Your first contact with Basement Force
When we first speak, we will ask you some questions about the property. This will enable us to give you an indication of cost. We will need to know:

  1. Where you live and the size and style of the property
  2. If you have an existing cellar or basement, its size and current headroom
  3. What you are hoping to create (usage and size of rooms together with requirements for natural light)
  4. Your budget

The last question is not leading. We fully expect you to obtain alternative quotations and we will be as competitive as we can with our figures. The reason we ask the question is to help you establish if, given the information you provide, your expectations are realistic.

Site visit and quotation
We will meet you at the property to talk through your requirements and take measurements to enable us to calculate costs in more detail. Following this we will prepare a detailed quotation, which is generally grouped into categories (such as waterproofing, carpentry and electrics) to aid your understanding and to provide greater transparency.

This first quote provides a good indication of the cost of the project. We will then address the following issues to enable us to agree an accurate project scope and final contract:

  1. Production of architectural drawings and details
  2. Assessment of the structural loads and calculations
  3. Resolution of any issues associated with party walls or adjacent buildings
  4. A ground investigation usually comprising the excavation of trial pits

In the event that you decide not to proceed, or if you elect to use another contractor, then you would only pay for the work we have carried out for you.

The construction of the basement
Once we have agreed exactly what will be built, planning permission and building regulations approval are obtained, and party wall consents are in place, we will be ready to start.

The file will be handed over to one of our engineers to run the project. Following this handover the engineer will call you to arrange to visit the site and discuss any concerns or issues you might have. We will indicate our proposed programme for the works and give you a provisional start date.

The works will be undertaken on site by a team of between two and six men working under an experienced foreman. The foreman will work under the supervision of a Basement Force engineer.

For each phase of the project, the team will have been issued with a written schedule of works. The schedule will describe in detail the scope of work and the timescale. The engineer will usually meet the foreman on the first day and go through the works, and there will be frequent inspections to ensure that everything is being constructed as planned.