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APT Renovation Basement Conversions London – Basement Company London

We can take care of all aspects of basement conversion project throughout whole planning stages and design process, excavation to construction of the core base and waterproofing finalizing with fit-out and completion. APT Renovation offer a complete basement conversion and renovation service. Our own construction team will undertake the whole fit-out phase of the basement conversion project. The major benefit of our service that you can work with a single team of specialists under one roof. These Include:

Design Consultants, Architects, Structural Engineers and Builders who have over 10 years of experience as a team in modelling, designing and building beautiful homes across London. We can also take care of all aspects including planning applications, project cost estimation, development of detailed designs, and specification of fine materials and finishes.


basement conversion entertainment room
basement conversion gym

APT Renovation is basement specialist in London who has extensive experience and able to deliver basement conversion requirement on time, budget and meet your expectation.

Frequently Asked Questions (FAQ).


Our clients always ask this question, as they would like to get a rough idea regarding the cost. However, the reality is that the answer is never straight forward because each individual project will be different and will depend on a number of aspects. We need to closely look into multiple factors such as the materials needed, the clients’ vision, the budget and the timeframe before we can give a clear quotation. With that being said, we can give a rough estimate during the site visit meeting. From our previous experience in basements, we can give some understanding of what you might expect:


£4700 – £6720 PER SQ M APPROX.

This figure is a rough idea at what cost a basement conversion in the Wandsworth area will be. The range is a correlation between the different level in finish. There is always the possibility of other costs being incurred when looked at in greater depth.


£1200 – £2400 PER SQ M APPROX.

We use Delta membranes for damp proofing. Depending on the state of the walls and the ground, Damp proofing membranes can be used to full or medium coverage.

Is planning permission obligatory?

For the most part, you will not need a planning permission for a basement excavation, as the changes do not breach the area of your building plan and usually wont exceed outside your building structure. However, there are times when parts of the basement conversion project may require planning permission if it does goes outside of the building plan. Your local council is the first contact point when it comes to the planning permission.

It is always recommended that you should be familiar with basement conversion requirements before you start planning your project.

Do I gain financial benefits from a conversion?

Not only does adding additional space improve the scale of a living space and boosts comfort, market research shows that you will also gain financial benefit if you wish to sell your property in the future. Basements can be transformed to amazing living spaces such as wet rooms, spas, pools and entertainment rooms with proper ventilation and heating.

It’s important to remember that the value of your property can skyrocket after a basement renovation.

We will visit you at your premises to discuss what you would like to create within your new or existing basement space. We are happy to answer all essential questions you may have during our initial visit.

We offer a full service which includes submitting plans right through to the very last detail, or we can just create your basement conversion project from your existing gained plans. APT Renovation will send you a quotation within 4 days.


Free a No Obligation Site Visit / Consultation

APT Renovation will visit you at your premises to discuss what would you like to create within your new or existing basement space. We are happy to answer all essential questions you may have during our initial visit.
APT Renovation can offer a full service which includes submitting plans right through to the very last detail, or we are happy to just create your basement conversion project from your already gained plans.
APT Renovation will ensure to send you a quotation within 4 days.

Design Service

If you require a Planning and Design service for your basement conversion project, our in-house Architects, Structural Engineer, and Party Wall Surveyor are at hand to help you visualise your plans and go through them with you until you are completely happy with the final ideas. Our primary concern is to make our clients happy, so every process will be explained to you from beginning to end.

British Standard 8102:2009

British Standard 8102:2009 is the ‘Code of practice for protection of below ground structures against water from the ground’. In essence, it is the primary design guide for structural waterproofing in the UK, with the recent update being released in November 2009. If you are producing a waterproofing design, or you have advisors that are designing on your behalf, this document should cover every consideration possible. If you have further questions in regards to the BS8102, please feel free to contact us.

basement conversion tanking


Tanking, or ‘Type A barrier protection’ (BS8102 definition), is a specific form of waterproofing, although it is a common term applied to all forms of waterproofing. In the true sense of the word, tanking means blocking water out of a structure by employing a barrier product which is installed internally, sandwiched within, or applied externally to a structure. Tanking is still widely employed in new construction, but has declined in popularity in recent years where retrofit protection is required for existing basements.

basement design and build excavation


An intuitive construction process of all basement conversion projects is monitored and overseen by managing director, Andi Pepaj, and managed by our project managers onsite.

APT Renovation has over 17 years experience in underpinning and basement excavation following basement standards at very high level finish.

You will be advised by your Project Manager who will be on site all day, every day and will be your first point of contact.

health and safety during basment excavation

Health and Safety on every stage

Health and Safety is of the utmost importance on every site that we work on, as it not only concerns all of our staff members, but everyone else in the vicinity; including you, your neighbours and even passers-by. Due to the nature of our work, there is always the risk of injury or even death, as ladders, tools and various other materials can be hazardous. Basement conversions in particular are technically very challenging, and can pose a number of different risks, with a large proportion of these projects in London regularly failing safety checks. Unguarded excavations and unprotected floor openings represent serious dangers to all those concerned. That is why our staff are expertly trained and will always diligently adhere to all necessary Health and Safety procedures and issues.

basement conversion waterproofing


Waterproofing is a very important aspect in basement conversion, particularly as the UK experiences a very high level of rainfall each year. A lack of waterproofing will eventually result in damp on walls, which not only look bad, but smell bad as well, and can cause significant damage to the paint job, the plastering and the finish. Worse still, damp can also lead to breathing problems and other health issues, so it is something that should be nipped in the bud.

APT Renovation have had huge success over the years in waterproofing with Delta Membrane Systems and pumps. For basement waterproofing, the Delta sealed system ensures that all membranes are expertly sealed and secured, as well as any protrusions or crevices. Delta Systems are incredibly effective in dealing with adverse water conditions and especially basements that have the propensity to flood. There is an offer of a 30-year guarantee on all Delta membrane systems.

Visit the Delta website

basement conversion fit out


Our construction team will be ready to make the rooms or space in your basement that you have been dreaming of, come to life. Our dedicated and experienced tradesmen will work tirelessly to complete your project on time with no stone being left unturned. Our aim is for you to be completely happy with the work, and we will only sign off the project once you have deemed it necessary to.

Insurance and Guarantees

APT Renovation hold public liability insurance, and an all risks cover. This will cover you and our builders. APT Renovation Ltd offer a 15 year warranty on all structural work.

With hundreds of basement conversion projects completed to date, APT Renovation has an outstanding reputation for being basement conversion specialists, dedicated to creating state of the art spaces, with immaculate attention to detail.

With over hundreds of basement conversion project completed to date APT Renovation has an outstanding reputation for being basement conversion specialist, dedicated and attention to detail driven.

Book a Site Visit

APT Renovation team are always happy to hear your thoughts about your project, either on the phone or in person.

If you’d like to know more please arrange a FREE no obligation site meeting you.

Call Us: 0207 223 6417

Email Us: [email protected]

Office Opening Hours

Mon   08:00 – 17:00
Tue    08:00 – 17:00
Wed  08:00 – 17:00
Thu   08:00 – 17:00
Fri     08:00 – 17:00

Outside of these hours, please leave a message and we will call you straight back.

If you are an existing client and need to contact us urgently, please call the mobile number of your Project Manager

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A Building Inspector will visit at regular stages throughout the project, their job is to make sure that we are adhering to all the latest building regulations. Upon completion of works The Building Inspector will make a final visit and you will be issued with a completion certificate.


Upon final completion of basement conversion project the client will receive following documentation where applicable:

Gas Safety Certificate, Electrical Sign Off Certificate, Drainage Layout, Plans as Built Drawings, Manufacturers Instructions For Appliances, Manufacturers Guarantees For Appliances, 10 Year Structural Guarantee

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