We have evolved a method of planning, preparing and executing this work that involves a marriage of consultation, creativity, technical expertise and uncompromisingly high standards of workmanship.
Our tradesmen are carefully chosen and work exclusively for the Big Basement Company, so they have a ‘stake’ in the successful completion of each project we undertake. We believe our commitment to the tradesmen we employ generates a level of pride in their work that translates to customer satisfaction unrivalled by other firms.
We are fully familiar with the working practices of professionals such as architects, engineers and party wall surveyors who will be involved in the creation of your basement and we are happy to introduce you to these professionals, if you have not already employed the services of your own choice of firm.
Many of these companies have worked with us for a number of years and through that we have evolved a methodology which ensures a prompt and efficient service. Our professional partners are completely independent, ensuring that you receive entirely impartial information and advice.
As you will quickly realise there are many facets to building a basement and many choices to be made. The advice contained within this website will assist you in understanding the costs and processes associated with the completion of your project.
Over the years, The Big Basement have completed many basement projects, of varying sizes and complexity, so you can be assured that we are ready, willing and able to deliver your dream.
AREAS WE OPERATE IN
We are based in West London and operate in a large area covering London, Middlesex, South Buckinghamshire, South Hertfordshire and Surrey. Other surrounding areas will also be considered dependant on the type of project.
SERVICES
The Big Basement Company prides itself on the quality of its work and all the people involved in operation.
We can provide access to all the key professions so that design, planning and party wall awards are handled quickly and efficiently.
Throughout the entire process we aim to keep the client fully informed of developments and activity to ensure that their aspirations regarding costs and timings are met.
During the construction phase each project is allocated a dedicated foreman who is responsible for all the day to day running of the operation and can provide the first line of communication with the client. The foreman is also responsible for ensuring that the site is kept clean and good neighbourly relations are maintained.
Each project is also overseen by a Contracts Managers who will visit the site daily and will work closely with the designers and engineers on a matters arising.
Throughout the build, the client will have access to a 24hour contact number which can be used if they have any concerns relating to the works.
CONSTRUCTION GUIDEThere is a lot of information contained within this guide but we feel it would be worthwhile for you to read it all, that way there will be no surprises and you will be able to tell friends, relatives and your neighbours about what is going on.
We look forward to the opportunity of working with you to build your ideal living space.Before you can progress with your plan to have a basement, there are some issues that need to be resolved in terms of you getting permission to build. These are largely to do with the sort of property you own, what you want to use your basement for and how the appearance of your home will be affected. Identifying potential restrictions now may save disappointment further down the line.
Leasehold Properties and Shared Buildings or Grounds
If your property is a shared building, has shared grounds or you are a leaseholder, it is necessary to serve the appropriate notices on all the other parties as part of the planning application. The freeholders ‘consent in principle’ should be obtained before applying for planning permission. Most leases do not allow structural alterations to be made without this so refusal would make the whole project impossible.
You will also need to ensure that any proposed light wells are on land owned by you and do not impinge on the common parts of the grounds or obstruct a right of way.
Creating a Separate Dwelling
Many local authorities do not view the creation of additional dwellings favourably, particularly where it is not a common feature of houses in the same street. This does not entirely rule it out but it may be worth talking to your local planning department in advance of spending any money, to obtain even a verbal consent in principle.
Conservation Areas
If you live in a conservation area, you will need to find out whether there is a general objection to basements in the area and if not, what guidelines have been laid down relating to external appearance.
Assuming that these matters do not present an obstacle, you can move on to the next stage.
LEGAL & ADMINISTRATION
Planning
The purpose of the planning system is to protect amenity and the environment in the public interest. Within a framework of legislation approved by Parliament, councils should try and ensure that development is allowed where it is necessary, while ensuring that the character an amenity of the area are not adversely affected by the changes.
Most basements projects are considered to be uncontentious forms of development as they have little visual impact on the way a house looks, they don’t overlook neighbours or take away natural light.
However, in some areas there are rules to be followed if you are to obtain planning permission and some London boroughs have gone as far as to publish guidelines. These rules usually apply to the design of the light well and are aimed at maintaining the look of the street, especially where the houses are terraced or semi-detached.
Whilst the planning application can be undertaken by an individual we would always recommend the use of an architect.
For further information on planning topics check out www.planningportal.gov.uk
Party Wall Awards
The ‘Party Wall Act 1996’ came into force on 1st July 1997 and applies throughout England and Wales. It provides a framework for preventing and resolving disputes in relation to party walls, boundary walls and excavations near neighbouring buildings. Anyone intending to carry out works of this kind must give adjoining owners notice of their intentions.
Adjoining owners can agree with the building owner’s proposals or reach an agreement on changes in the way the works are carried out or their timing.
Usually the building owner will pay all costs associated with drawing up the award if the works are solely for his/her benefit.
For further information on party wall award topics check out www.odpm.gov.uk/partywall-1996
Formal Contract
In most cases this will be in the form of a JCT Home Owner Contract, where no architect is involved, or a JCT Minor Works Contract which is produced by an architect. Whilst these industry standard documents are relatively easy to understand you should examine them thoroughly if you have any doubts at all then we would suggest that you consult a solicitor with experience in this field of work.
Once you have signed the contract, all the permissions are in place and you have paid the relevant fees, we are ready to book a date to start work.
Health & Safety
Prior to commencement of the works a full health & safety review would need to be carried out and documented. As part of this process, method statements, risk assessments project specific information would be collated for the contractor and any other interested parties.
Household Insurance
You will need to notify your household insurer that you are having a basement built before the work starts as your requirements for cover will change during and after the construction period. Where necessary, we can provide copies of all insurance documentation for your insurer’s records.
AFFILIATES
Throughout the planning and building stages you will come into contact with a number of affiliates, all of whom have specific tasks and responsibilities. Below we have listed the most common but this list is not exhaustive.
Architect
The architect will be responsible for the submission and progressing of your planning application whilst handling any specific local authority requests regarding flood risk assessments, conservation and tree preservation.
If required the architect can oversee the project throughout the build, liaising with all the necessary personnel and confirming valuations.
Structural Engineer
When a structural engineer is appointed he will inspect the house and based on the architects design, recommend a scheme to support the existing structure. Before a scheme can be finalised, you may need to obtain a ground survey and this could entail digging a ‘trial hole’. The engineer will be constantly involved throughout the build and his final drawings and calculations will be used to obtain Building Control approval.
Party Wall Surveyor
Your neighbours will need to be informed about your intention to have a basement and if you share a wall on any side of your property then the co-owner of the party wall will have to consent to your method of development. The party wall surveyor will prepare documentation to be submitted for your neighbour’s agreement. Should your neighbours contest the application, the party wall surveyor will handle the dispute on your behalf.
Basement Contractor
The contractor is responsible for construction of the basement (shell & core) and where applicable the fit out and finishing.
The Big Basement Company would work with all the individual professionals during the planning, development and building of the basement to ensure that the client’s aspirations are met.
Your basement project would be overseen through construction by an on-sight foreman, supported by a Contracts Manager.
Interior Designer
Once planning permission has been granted you will need to consider the fit out and finishing of the project, this can be done by either your architect or a specialist interior designer.
Using the services of an architect or interior designer will save you stress, time and in the long term, money. They will consult with you about your ideas and wishes and produce a detailed layout. They will also do all the research and show you pictures, drawings and examples of finishes and products. They will liaise with the structural engineer if necessary and with contractor to ensure that all the features you want are accommodated. They can also be available to manage any issues arising during the fit out of your basement.
A complete interior design service could include detailed designs and specifications for specialist joinery, flooring, staircases, windows, bathroom and kitchen layouts, wall coverings and furniture, ironmongery and sanitary ware, built in audio visual units and lighting, decoration and external items such as protective grilles or railings.
District Surveyor
Employed directly or indirectly by the local authority, the surveyor’s responsibilities are to oversee the project to ensure that the works are carried out in accordance with the design, agreed building methods and current building regulations. At the end of a the project the surveyor will issue a Completion Certificate in accordance with building regulations.
The timeframes for getting a project to the start on construction can vary immensely from property to property with the principal influencing factors being the planning process and the party wall notices.
The process can take up to between four to six months from your initial inquiry, if all parties act promptly, but you should be aware that this timeframe can be affected by many different factors.
Planning Permission
Under planning guidelines, the local authority should decide on your application within eight weeks of receipt. If this cannot be achieved they will usually seek your written consent to extend the period.
This eight week period does not take into account the pre-planning work that may be required by the various local authorities such as flood risk assessments, detailed drawings and building calculations.
Party Wall Notices
Wherever possible, party wall notices should be issued at least two months before you anticipate the commencement of works.
Whilst most party wall awards will be concluded within an eight to twelve week period delays can arise where there are multiple applications (in the case of flats), the owner is difficult to locate or the project is particularly complex.
Throughout this process the surveyor may require additional information from any one or more of the contractor, architect, structural engineer and health & safety advisor.
It should be noted that party wall notices remain valid for one year only.
Design Amendments
During the pre-construction stage the project design could be changed for a number of reasons:
All of these will potentially impact on timings if they are not communicated and acted upon efficiently.
The construction stage covers the main structural elements of the project and is also referred to as the ‘shell and core’. Below we have listed the key parts to this stage.
Hoarding
Before work is started on your basement the site will be enclosed in a hoarding. This will make the site secure so that the contractors equipment is kept safe and your home is protected and secured. It will also contain the site, minimising the impact of dust, noise and general disruption to you and your neighbours.
Excavation
The excavation starts by digging a hole beneath the front elevation of your house to provide a route out for the debris from the dig. Digging under your house may sound, and look, a bit alarming but this is an established procedure, used to create hundreds of basements.
Initially the dig is straight down, then in under the wall or bay window and as the hole gets bigger, the structure is supported with steel props. When the cavity is big enough, a conveyor belt will be introduced to bring out the soil to street level where it is deposited into a skip. The site should be left clean and tidy at the end of each day.
Underpinning & Structural Reinforcement
Underpinning is a technique usually used when a building is affected by subsidence and it works by extending and strengthening the foundations, so that movement of the surrounding land will not compromise the structure. In your build, the foundations of the house will be extended downwards to accommodate the headroom requested whilst providing a stabilising ‘toe’ at the bottom. The underpinning is carried out in sequence around the perimeter of the excavation as instructed by the Structural Engineer.
Where the house is supported by lateral walls or pillars, ‘Rolled Steel Joists’ (RSJ’s) or other structural supports will be introduced, as specified by the Structural Engineer.
Drainage & Sump
Once structural support is complete, the floor of the excavation is levelled and trenches dug to allow for drains to be laid. These drains will take away the waste water from lavatories, sinks and showers and they will be served by a ‘foul’ pump which discharges waste into the sewage system. From this part of the process you can start to see how important it is to have the final layout and location of appliances agreed at an early stage.
A ‘sump’ will be dug, which is a cavity set below the level of the floor that will hold any ground water that has been directed there by the membrane surrounding the basement. The sump will contain a pump to discharge accumulated ground water into the drainage system.
Concrete Slab Floor
When the drains have been laid in their trenches, a layer of concrete is poured to provide a level concrete slab floor. Access points to the drains, sump and pumps will be provided for maintenance purposes. This forms the basis of your specific floor structure.
Membrane
The main method of keeping a basement dry is to use a membrane system. The purpose of the membrane is to keep the moisture caused by ground water out of the basement and to prevent strain on the walls. The moisture is kept out due to the design and impermeable nature of the membrane, resulting in water build up being directed to the sump.
The outward facing surface of the membrane is dimpled, creating a space between the concrete face of the foundations/underpinning or slab floor and the membrane itself. Thus, the water is free to flow down to the lowest point in the structure which is the sump. Once a certain amount of water is collected in the sump, a float activated pump starts up and pumps it into the main drainage system.
Insulation & Under Floor Heating
A thick layer of insulation is laid on top of the membrane which is an essential energy saving measure. Without this layer, the basement could become rather cold and use up excessive heating resources.
Where under floor heating is to be installed, the networks of pipes which carry the hot water are laid on top of the insulation.
Screed
Screed is a dilute concrete mix which is poured in a thick liquid consistency. This means that it will find its own level and although it takes time to dry out, it will always result in a perfectly level floor. Once it has been poured and dried, we have completed the stage we call ‘Shell and Core’ and we are ready to start to fit out the interior of your basement.
FREQUENTLY ASKED QUESTIONS
What can I use it for?
Your basement can be used for many different applications although some local authorities may advise specific restrictions. The most common uses are entertainment rooms, play rooms, kitchens, bedrooms, study or office, utility room and leisure facilities such as gyms, sauna’s, steam room and swimming pools. The area can also be made into a self contained living area for a relative or au pair but there may be some planning issues if you want it to be a completely separate dwelling.
Should I move instead?
Moving house is always an option, as long as a suitable property is on the market and you are happy to deal with the upheaval of moving. However the cost of moving could outweigh the cost of building a basement once you take into account price differential, stamp duty and associated fees. A substantial basement, dependant on size and finish, could cost considerably less than that amount.
Must I have a cellar already?
In the vast majority of cases, we can create a basement from scratch, but if you have an existing cellar, the process may cost less to complete.
What headroom can I have?
The Big Basement Company recommends a minimum of 2.4 metres (approximately 8 feet) headroom but if you wish, we can increase it to suit your needs. Where a property has existing steps on the ground floor it may be appropriate to have differing head heights to ensure that the floor space is on one level.
How will it affect my lifestyle?
Any sort of building work on your home will cause some disruption in terms of noise, but as we are building underneath it, we will not be traipsing through your house all the time. Once excavation starts, access will be direct from the street.
What about security during the works?
The front of the site will be enclosed with a hoarding and access from the site to your home will be impossible until the stairs have been installed. If you simply continue with your usual security routine, you will be as safe as ever.
Do I need planning?
Yes. All basements require planning consent from the local authority and from other bodies if you live in a conservation area. The Big Basement Company will deal with all consent required on your behalf should you wish us to do so.
Must I consult my neighbours?
Unless you live in a detached property, standing in its own grounds, you will need to reach an agreement with you neighbours over "Party Wall" matters. You do have a right to develop your property but the correct notices must be issued and consents obtained. The Big Basement Company can introduce you to the appropriate professional to ensure that this goes smoothly.
How long will it take?
Obviously this depends on a lot of factors including the size and depth of the excavation, the type of soil your property stands on, the seasons, what facilities you want and the type of finish you require. But a basic basement under a West London terraced house could be complete, to a structural finish, within as little as 3 months after all planning and other consents are obtained.
How safe is a basement structurally?
A basement itself is very safe and the construction methods we use may actually enhance the structural integrity of your house.
Do you use sub contractors?
Everyone who works on your site will be employees of The Big Basement Company. We find that this instils a team spirit and a pride in the finished job that is second to none.
The exception to this is the professionals, ie: Architects surveyors, structural engineers who are independent. This ensures that you will receive impartial professional advice and information at all times.
Can I see a completed one?
Yes. If you would like to see a completed basement, we have many satisfied customers who would be proud to show around their new space. You can also arrange to visit works in progress by appointment. In addition, our gallery contains pictures of schemes we have undertaken.
How much is it going to cost?
There are so many variables that it would be meaningless to give a minimum or average cost per metre. Contact us and we will be happy to visit you to give you a rough quote with no obligation.
What form of guarantees do you provide?
All works undertaken by The Big Basement Company are given an ASUC insurance backed, 12 year guarantee whist the membrane system is covered for 30 years.
How do I arrange a quotation or further information?
You can contact us on 0207 096 7000 or email using the link below.
CONTACT DETAILS
The Big Basement Company Limited
Unit 2
158 Dukes Road
London. W3 0SL
Telephone: +44 (0)207 096 7000
Fax: +44 (0)207 096 7007
E-mail: enquiries@bigbasement.co.uk