Basement conversion: a step by step guide

The idea of more space is tempting for many Londoners. You might want an extra bedroom, a home cinema, or a games room. A basement conversion is one answer to the lack of space. For ideas, see our basement solutions. Here we set out the process of getting a basement done in West London.

1. Site visit with a surveyor

First, you choose a design and build construction company for your London basement project. Then a surveyor will visit your home to carry out the site survey. This is one of the most important steps. Surveyors advise you on what type of basement and layout suits your home. They will take the measurements required for the quote as well.

Quotations are usually split into two parts. One for the structural part and one for the fit-out costs.

2. Contract

You need to be happy with the quote. You also agree a budget with the design and build company. Then you will need to sign a contract and place the deposit. Once you have paid the first instalment, the planning can start.

3. Design and planning

At this stage, an architectural designer will visit your home. They take the measurements the planning application needs. Design and build companies, like NU Projects, handle the planning permission for you. That includes soil drilling and testing, and the structural engineering calculations. It also covers flood risk assessments and eco home assessments. They will assign a project manager. That person oversees the whole process of your basement project. You may have appointed your own architect. If so, construction companies will quote you for the construction part of the basement.

4. Party wall agreement

Each neighbour will have to be informed before you start your construction works. Obtaining a Party Wall Agreement is also required in one case. That applies when your home shares a wall with another property on either side. You may own a detached house. You still have to apply for a Party Wall Agreement in one case. That is if the basement conversion comes within 3m of your neighbours’ property. Each London borough has its own regulations. Companies like NU Projects can help you obtain a party wall award. They can also help with other documents. This saves you time and money during the process.

5. Building phase

First you need all the permissions and documents required for a basement conversion. Then the building phase can start. A basement conversion can take six to ten months. It depends on the basement’s size and what goes into the fit out.

The typical phases of the building process are

Structural works

Waterproofing

Contracting the shell and core

Glazing

The design and build company will assign a trusted site foreman. The foreman stays for the whole basement conversion. They will be in charge of keeping your project on time and budget.

6. Interior design

Most basement contractors focus strictly on delivering the shell and core of a basement. They do not include any fit-out or interior design service. You might sign up with a design and build construction company like NU Projects. Then you can include the fit-out and interior design in your basement conversion project. The interior design steps include picking

• wall formation, finishes, colours
• sanitary ware, tiles, paint colours
• windows, external and internal doors
• light fittings, lamps
• plumbing
• heating, ventilation, air conditioning (HVAC)
• joinery
• furniture
• decoration

A professional interior designer can help you make the most of the new space. They can also save you from costly mistakes.

7. Completion

Once the basement is complete, you receive all the relevant certificates. NU Projects hands over a guarantee and a warranty on the finished work. We also come back for the defects period afterwards.

Do you have a question about a basement conversion? Call us on 020 7731 6841 or email info@nuprojects.co.uk. You can also book a site visit.