If you’re planning a basement conversion you may have some questions in mind. We’ve put together a list of some of the things we are frequently asked by our customers

1. Why Should I Use BasementWorks?

BasementWorks are a part of OLBC Group which has been building basements in and around London since 2002. We have seen the others come and the others go. We have seen loft conversion companies turn themselves into basement experts.

With our unblemished insurance track record coupled with in-house design & planning department as well as our proven project management skills we are the obvious choice for the home owner.

Above all else when you walk into a BasementWorks basement you know you are going into something a bit special and timeless. Why not give yourself the BasementWorks advantage?

Simply give us a call and we will tell you if we are able to undertake your project and give you an estimate of the likely costs. If you want to proceed we will then come out and carry out a survey and give you a very clear idea of the structural costs.

There is no obligation in any of this: just clarity of purpose and process.

2. My existing basement/cellar has limited headroom and feels cramped - when we saw a BasementWorks basement conversion this didn't seem to be the case: why is this?

We typically design a basement to have at least 2.7 metres of finished headroom, more than your average London basement company would typically propose. We feel it is important to preserve the perspective of room size and height from the existing floors above so the new space doesn’t appear confined in comparison.

Equally important is that the height of the basement is balanced and proportionate to general size and width of the property: excessive height can look out of place. In the end it is up to you the client to choose the height that your require and suits your budget.

3. Why do modern basements not have the musty smell that old fashioned basement had?

Waterproofing technology has come on leaps and bounds since the early cementious tanking systems were used to ‘block out’ the natural passage of water. Most modern conversions use a plastic cavity membrane system that allows the moisture to run uninterrupted behind the membrane into a sump beneath the floor, which is then pumped away into the drainage system. This means that no differential pressure is created either in the structure or across the membrane, and also that a vapour barrier as well as a water barrier is created between the earth and the structure.

4. Do I need plans for my basement conversion?

For large structural projects detailed plans and specifications are a must as these enable us to provide accurate timescales and costs. They are also required for planning permission and for the engineer to work from.

5. How do I find out what permissions I might need?

Planning permission is usually required for large structural alterations or additions to existing buildings, and the erection of new buildings. Planning permission is not required for all types of works, as some works are classed as ‘permitted development’. In the first instance, your council planning officer will be able to advise you as to which controls your work will be subject to. If we are contracted to undertake all pre-works arrangements for you, we will look after these issues and obtain all relevant permissions on your behalf.

If your house is more than 170 years old or of special architectural or historical significance it may be Listed which means you will also require Listed Building Consent in order to carry out works. Such buildings are described as being either Grade I, Grade II* or Grade II in significance. This Listing potentially covers both the external and internal aspects of the structure. We will be able to advise you and seek the relevant permissions on your behalf. OLBC has expertise in these areas and we are a particularly good choice for your project if you have any specific concerns with regard to the safeguarding of any material of your property, or require any advice on sensitive restoration or conservation work.

6. Should I hire an architect or engineer for my conversion and how do I find one?

If you have not already commissioned plans or a structural engineer, we would encourage you to come direct to us for the entire conversion package. Not only can we offer you a cost-effective end-to-end service, we can free you of the responsibility of introducing professionals who may not have worked together before and may not share the same working approach. With our complete service the responsibility for delivering your project to site rests with our professionals who are experienced at working together to arrange basement excavation projects.

7. How long will it take to complete my basement conversion and when can we start?

The ‘pre-works’ element which is necessary to complete before work begins onsite will generally take from 3 to 4 months. In this time, we need to survey the site, agree plans for the basis of the new basement space, create a full quotation and specification, acquire planning permission, engineering, Party Wall awards, apply for street license and notify Building Control.

When on site the basic rule of thumb is to allow 16 weeks in the digging phase and around the same again for the structural and complete fit-out. There are many factors that can influence this average timescale, and you will be kept fully informed both before and during the project as to the timescale.

8. Will we need to move out during the excavation and conversion? If we stay, will there be much disruption?

If you are just excavating a basement in a house with suspended timber floors in most cases it is feasible to live in the house. If we are undertaking works beyond the basement, we usually recommend that the client vacate the premises. This has a positive effect on coat and duration, and is much nicer for the client. If we are only working underneath the house, it is highly likely that we can work with you in place. In this case we will seal any gaps in your ground floor to minimise the occurrence of dust, and keep all work areas screened off with our hoardings. Any work noise will be limited to our normal working hours. It would be unrealistic to suggest you wouldn’t notice we were there, but you should be able to continue using your ground floor as usual so disturbance should be minimal.

9. Does there have to be an existing cellar prior to the basement conversion?

It is quite normal to construct a basement where there is no existing cellar.

10. Do I need to advise my neighbours about the proposed basement conversion?

Yes you will need to notify them via the Party Wall process. This is the only part of the process that BasementWorks cannot carry out for you as the Party Wall surveyor is, by law, appointed by the property owner. BasementWorks can put you in touch with Party Wall surveyors with extensive basement experience.

11. What insurances are required for excavating a basement?

BasementWorks has the very highest levels of insurances for specialist basement excavation and basement conversion works. We are very proud that we have never had a claim against us in nearly 15 years of carrying out basement excavations and we can evidence this. We will put you in touch with an experienced broker to make sure that you home insurance is also correctly set up during the course of the works.

12. What guarantees are offered on the completed basement?

Waterproofing materials have a manufacturers guarantee of 30 years, waterproofing workmanship is guaranteed for 7 years. for All of our structural works are guaranteed for 7 years. We are able to offer marker leading bespoke underwritten warranties at very reasonable prices for the ultimate peace of mind.

13. Is it possible to take a basement construction beyond the footprint of the house?

Yes, we can continue the construction of a basement below front or rear gardens, including paved driveways, ground conditions and planning allowing.

14. When I have seen BasementWorks basements they appear light and airy and the space flows: how do you do that?

BasementWorks take great pride in the feel and appearance of our basement. Our experienced interior design team just design basements and they know what works. In short properly thought out design is the key to success.

15. Ten Top Tips for Planning & Designing Basement Conversions in Your Home

1. First decide how the basement will be used.

The key is working out what you need the basement for. It’s important not to create a room that can only ever be used for one purpose. By creating open plan, flexible spaces the room can be adapted to suit your family’s requirements. A cinema/games room would work just as well as a private annex for an elderly parent in a couple twenty years down the line. The charm of a basement is it’s multifunctional use.

2. Good preparations and planning can maximise value for money.

Understanding the fabric of historic buildings at this early stage is invaluable to the success of the project.

As part of the planning process we run several surveys, which are absolutely necessary in order to unearth what could potentially cause issues later down the line, and avoids expensive hiccups.
If you have all of the issues presented in front of you then you can find practical solutions from the offset. There is always a way to get around things. If the approach to the basement isn’t methodical it causes stress, expense and time for the client.

3. You don’t need an existing cellar.

It is often an existing cellar that sews the seed in client’s minds to consider going underground. People often think that it will be easier and cheaper if there is an existing cellar, but this is generally not the case. To make an existing cellar habitable the floor of an existing cellar the perimeter walls will still have to be underpinned. We usually need to excavate to 3.2 m to provide a standard room ceiling height of 2.7m. If you don’t have a cellar, a basement is still a viable option.

4. Basements cause less disruption than other work on a house.

In most circumstances, a basement can be dug underneath a house whilst the occupants remain there. We start by digging a light well at the front, and then progress under the house from there. It is possible to not enter the house until the very end, when the staircase and finishes are required to join it with the ground floor. Basement conversion companies are restricted to carry out construction works during set working hours and work must take place behind a contained hoarding enclosure. Also as the majority of works are carried out underground, the noise impact is significantly reduced to comparison with, for instance, a loft conversion, where the noise is external and not contained.

5. Arrange living spaces and bedrooms near lightwells.

Light wells provide natural light and ventilation, which is why bedrooms and living spaces work really well positioned next to them. Light wells will be positioned to the front and/or rear of a property, providing a connection between the internal and external area. Even seeing greenery through the window can create a sense of openness. If you are fortunate enough to have a side passageway then we recommend opting for a third light well here too in order to maximise the amount of natural light.

6. Place ancillary room in the mid-section.

Ancillary rooms less needy of natural light, such as laundry rooms, shower rooms, plant rooms and storage areas, as well as staircases, are usually best placed in the mid-section.

7. Embrace the modern- don’t replicate the floor above.

A basement is an opportunity to start your design from scratch in terms of style. A continuation of styles, and attempting to replicate architectural details came come off as pastiche. It’s an opportunity to add your own sense of fun and modern style without having to worry about matching existing architectural features. Embrace modern design and create a subterranean elegant decor that will add another dimension to your home.

8. Use glass balustrades to establish entrance into a new space.

A solid oak or walnut staircase with glass balustrades, very simple doors and square-profile moulding will signal your entrance to a very different space and establish a new character.

9. Angle the staircase so you arrive in the centre of the space.

People often underestimate the importance of the hallway. Although you don’t spend a lot of time in there, other than passing through it, it should be one of the principal concerns because it is the first area you reach. You want to have a sense of openness as soon as you enter the basement. First impressions count.

Consider angling the staircase or twisting it so that you are put into the centre of the space, rather than facing a solid wall. Avoid a design, which features a long thin underground tunnel with box rooms leading off it, creating a rabbit-warren effect!

10. Create the impression of increasing space by using a canted hallway.

Depending on the architecture of the house, you may be able to introduce a canted wall to the hallway to create the impression of increasing space, while floor-to-ceiling glass panels move light around and create a feature in the hall.

Sometimes the most spectacular area of an otherwise ordinary home is at its subterranean level – a trend that’s set to continue.