FAQs

The first thing to consider – is it financially viable for you? We can give you a no obligation quote for your basement shell before you commit to any financial outlay.  You can then decide if the project is feasible. If you decide you’d like to proceed, you will need an architect to draw plans and submit a planning application for you. Depending on which borough you live in you may need a structural design, site investigation, traffic management plan and construction method statement to be submitted with your planning application.  We can advise during this quotation phase to ensure you have all your bases covered.

Most basements do require planning permission. Certain schemes can be carried out under permitted development but most schemes that involve alterations to the external appearance of the property will need to go through the planning process. You need to allow up to 8 weeks once the local authority has received your planning application for a decision.

Building a basement is not cheap but neither is moving to a bigger property. It often works out cheaper to pay for the additional space in your existing property than moving. It is best to investigate the ceiling price of properties in your road or area and speak to estate agents to get some budget valuations to see if this works for you.

Your new basement space can be used for anything.   Over the years, we have built basements for gyms, cinemas, swimming pools, saunas, hammam spa rooms, steam rooms, games rooms, media areas, music studios, utility rooms, extra bedrooms and bathrooms, kitchens and family rooms, plant rooms, the list could go on.

We can build a basement on almost every property, as long as there is a form of access to get materials delivered and spoil removed. There are also additional restrictions to be considered on some listed buildings that your architect can advise on.

Usually a single storey basement will have a finished floor height of between 2.4m and 3m. We can build more than one storey should your planning permission allow. When considering ceiling height it is important to remember that additional depth will have an impact on cost.

When you think of a basement you may think of a dark damp area below your property where you store your junk but times have changed!   The key to any basement build is to get as much natural light as possible.  With good design choices, you can get light from front lightwells, side lightwells, and rear stairwells with sunken terraces. There are many new and inventive ways to maximise the light in your basement.

If you live close to or are adjoined to your neighbours a party wall award will be required before works start. You will need to appoint a party wall surveyor to go through this process with you. This can be a tricky but we can advise should you wish to proceed with your basement.

Firstly, decide if you want a full turnkey service or to split the works between structural shell and fit-out. BaseSpace London can offer you the shell package and offer advice on all elements of the build.  We can put you in contact with our trusted partners for the fit out phase or you can use a builder you know.

Basements are a complex and specialist type of construction and you must employ a contractor with vast, verified basement experience. It is not worth taking the risk with a cheaper, less experienced contractor, who may save you money here and there – but could cost you a lot more in the long run.

It is also important to get references and not to rely on a fancy website. Ask your potential contractors to visit a site/sites in progress to see how they work. If the site looks a mess and the health and safety is not good, the works are likely to be sub-standard too.  We welcome and encourage clients to spend time at our sites to understand the process and see our teams at work.

Unfortunately, there is not a simple answer to this question. There are so many variables that can affect the cost of basement construction. Costs can vary depending on the size and depth of the footprint.  There are fixed costs with any build so generally, a smaller basement will cost more per sqm metre than a larger basement of the same depth.  The height of the finished basement is a big factor, as well as access to site, ground conditions and the local authority you live in. London boroughs have their own rules on vehicle access and different costs for parking suspensions and licences, which can also affect costs.  We have worked with most London boroughs and can advise accordingly.

We have found that many basement companies quote competitively to win business but then add to the quote during the build.  It is something to be aware of as extras can add up considerably.

Once we receive all the information and plans from your architect, we will be able to give you fixed quote for your structural work, and you will see what is/isn’t included. The only additional costs that could be incurred are for unforeseen circumstances, such as, finding hidden concrete beneath your property that would need to be broken out and disposed of.

If any changes are made to the design or plans, this would also need to be re-quoted for. We will advise up front of any additional costs and get your prior agreement, before any extra work is undertaken.

There will be no hidden costs with BaseSpace London as we offer transparent quotes. When choosing a contractor is important to know what you are paying for, and that costs are not going to spiral. Every part of the works will be itemised in a written quotation and explained to you prior to agreeing the works.

We recommend speaking to your current insurance company to see if the work will be covered by your current policy. It is possible to take out non-negligence insurance but this will be at an additional cost

This really depends on the scope of work you require.  If you are only having basement works carried out, then it is more than likely you can stay in the property. It can be a bit noisy and dirty, but it will save on any additional property rental costs.  We create a hoarding that will conceal the works and keep the outside areas pristine for you and your neighbours.

If you are having works done to the basement and the upper floors it is advisable to move out until such time that at least some of the property is liveable.

We would advise, and always welcome any potential clients to come and visit a site in progress. It will give you confidence that we know what we are doing and that we work in a clean and safe environment. You will get to meet our site managers and the teams, which will give you a good indication of who we are and who you are potentially contracting for your basement works.

We are specialists in structural work and stick with what we are experienced in. We leave the fit-out to experts in that field. It can be tempting to a ‘turn opt for a ‘turn-key solution’, but we have seen many basement companies take on fit-out work over the years and it doesn’t guarantee expertise in every aspect of the project. We work closely with many fit out contractors and can recommend the most suitable company to you, based on budget and specific requirements. The best team to fit-out a cinema room may not be the best fit-out team to build a swimming pool. We are also happy to work with your own fit-out contractor and we will we work together with them to give you your dream basement.

This is dependent on the size and complexity of the scheme. A standard basement shell on a terraced property can be done in 4 months but it could take up to a year or more for a large basement.

We will be able to give you a timescale with our budget or confirmed quotation.

Once we start work, you will be introduced to your team and site manager, who will stay on your site until completion. We do not move teams around from different sites and intermittently carry out works.  It is in everyone’s best interest to finish the work as quickly as possible. We will have a dedicated experienced team on hand to complete in the fastest and safest way possible.

All our sites will have an experienced, dedicated site foreman with the relevant health and safety certificates to carry out the works. Our project managers will also visit site every day to ensure the design and procedures are being followed.

The local authority building inspector or approved building inspector will sign off all the major aspects of the structural work and ensure all aspects of the design have been adhered to.

Basement work can be difficult and challenging from a health and safety prospective. We begin every project with a health and safety meeting to ensure that the site is set up properly from the outset.

All of our teams also have the relevant health and safety certificates to carry out the tasks required.

We pride ourselves on our excellent health and safety and employ an external H & S company to audit every site at least once a month. They issue a report outlining any items that need addressing. It is important to have this extra pair of trained eyes to visit our sites and point out anything we can do better.

This is possible, but not recommended as it will nearly always incur additional charges and slow the process down. It also depends on what stage of the build we are at.  We always do our best to accommodate our client’s needs, but we strongly recommend focussing on the planning stage to ensure you are 100% happy with the plans. If we have constructed major structural walls or installed main steel beams it can be expensive to change, and we don’t recommend  deviating from the design too much. We can usually make minor internal layout changes, but we will require the details before any pumps or under slab drainage are installed.

We often carry out works to the upper floors of the property in tandem with the basement works. This is usually beneficial to the programme rather than waiting for the basement to be completed, then starting the superstructure.

We can also work in conjunction with other contractors on site, as a sub contractor, as long as we all follow the correct health and safety procedures.

This is one of the most important aspects of your basement build. As Delta Membrane registered installers, we have vast experience in basement waterproofing. We treat the concrete structure with the necessary products to ensure that there is no ingress of water prior to installing the membrane system. This 2-tier approach to basement waterproofing will give you, and us, confidence in our work.  We are very happy to take you through the waterproofing in more detail if you require it.

We are well aware that basement building can be disruptive to your neighbours but we try to minimise this as much as possible.

Prior to commencement, we will send a letter out to neighbours, outlining what we are doing, how long it will take, any contact details for emergencies and concerns they may have and try to reassure them we are a responsible company and that we will try and complete the works as quickly as possible.

We will ensure the road is clean and safe for passing pedestrians and traffic with dedicated labour to carry out this task.

We can also work with your neighbours to schedule quiet work if they have an important meeting or event on at home. We do try and be as accommodating as possible without putting the programme behind.

Not if you get the right experienced contractor for your project.

Prior to work commencing, we write and compile site-specific method statements, risk assessments and a full temporary works design by structural engineers with an extensive knowledge of basement design. This design must be followed and any changes agreed by the structural engineer prior to works being carried out.

We offer a 10-year company guarantee on the structural works and a 30-year product guarantee on the waterproofing system. A registered installer must issue the waterproofing guarantee.

It is possible to get a 10-year insurance backed guarantee on the waterproofing system. This is not generally included in the initial quotation but costs can be provided on request.

If you get in touch by phone or email as soon as you have any issues we can deal with them straight away. If it is something that needs a site visit, we will send someone round within 24 hours to assess the situation and remedy anything that needs addressing.

Prior to your fit out contractor starting works on site, we will have a handover meeting to go through all the work we have done and explain what they need to do to coincide with our works. We will swap contact details and be on hand to visit site to go through any queries they have. We are always at the end of the phone during the entire build.

You will require a pump-commissioning certificate for any pump systems you have in the basement. We will arrange the commissioning of the pump systems for you and this will be included within our quotation.

In addition, you will need to take out an annual service agreement with a pump company to make sure you keep the pumps in good order.