Basement Conversions

Convert Your Cellar Into a Habitable Living Space With a Basement Conversion
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London Basement Conversions & Extensions

Building Vision London specialist builders can transform your empty underground or partially underground basement from an under-utilised storage area into a brand new, valuable living space whilst also increasing the value of your property. We can also extend your existing basement footprint under your garden area, with a 'walk-on' roof-light if space allows.

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partial underground basement conversion livingroom and sittiing / diningroom with highlevel Clerestory style windows providing daylight
kids basement playroom with full height folding glazed doors to a sunken garden patio
a fully underground basement extended under te garden with a walk-on rooflight showing the basement conversion below the garden

Don't Move! We Make it Easy to Add an Extra Room in Your Basement

Building Vision London can help with every aspect of adding a habitable extension to your home—from a loft conversion to a single or double-storey extension and a more specialised and complex basement conversion.  Working together with architects, interior designers, and local building regulation and planning officers during the detailed design, planning and budgeting phase, we handle every aspect of the construction, water-proofing and finishing of your new basement conversion and extension. 

A Basement Conversion Can be a Great Economic Investment While Adding Extra Living Space

No Room To Extend? If your garden is too small for an extension, your loft is not suitable for conversion, and moving house is not an option, a basement conversion may be the solution you seek. A basement conversion can add significant value plus extra living accommodation, especially in London, where building land is scarce plus property values are high.

We have worked on many London basement conversions to expand and improve existing cellars. We can dig underneath your property to lower existing cellar floor levels to improve ceiling height and even horizontally below gardens.

The list of potential uses for basement conversions is many and varied. Basements make an excellent entertainment/games room, wine cellar, bar, man cave, gym, kids' playroom, home office, utility room, home TV theatre, granny annexe (complete with living room, bedroom, kitchen & bathroom), and even underground swimming pools.

The Typical Basement Conversion Process

For most straightforward projects, here’s how we transform your basement into a luxury living space under your feet.

  • All existing floor and ceiling coverings are stripped out and removed
  • If ceiling height is insufficient, the existing floor is dug out and lowered
  • All rubble is removed, via an existing window or doorway if one exists
  • If required, a channel is dug and a sump + drainage system is installed
  • If required, new steelwork to support floors and walls is erected next
  • Above ground openings are optimised for light + to provide a fire escape
  • First fix plumbing and electrics are installed and rerouted as required
  • Water-proofing + a cavity drainage membrane system is fixed to external walls
  • A framework is installed to accommodate insulation + cover electrics and pipework
  • New internal plasterboard walls are installed + a new staircase to upper floors
  • All ceilings & walls are insulated to prevent heat loss + receive 2 coats of plaster
  • Staircases are upgraded + new windows. lightboxes and doors are installed as required
  • Finishing touches e.g. radiators, flooring, painting & decoration and light-fitting installation
  • If the new basement extends outward under your garden we handle all landscaping required
  • Finishing touches include installing kitchens, bathrooms, telecoms + home cinema systems

Typical London Basement Conversion Costs

Depending on the complexity of the conversion project—e.g. does a cellar pre-exist, how much digging will be necessary, how you plan to use your newly converted basement—a host of questions need answering to provide an accurate price. But as a guide, basement conversion costs in London are likely to cost in the following range:

  • Conversion of an existing cellar will cost from £750 – £1,500 per square metre
  • To lower the floor level + underpin an existing cellar costs £1,500 – £2,000 per square metre
  • Digging a new basement space + underpinning will cost: £2,000 – £3,000 per square metre

Get a Quote For a Basement Conversion in London

If you are considering converting or extending your southwest London basement but need more information on the process, options and costs involved, we would be happy to visit you to inspect the property and discuss your needs without charge or any obligation.

We can also advise on building regulations and whether planning permission would be required. For example, if you want to add a multi-level basement, extend your basement horizontally beyond the footprint of the main building, or install a swimming pool in your basement—budget permitting.

We can also advise on fixtures & fittings, appliances, carpentry, doors, staircases and fire escapes. We have specialist lighting design knowledge and supplier connections for high-level Clerestory and roof-light windows for basements that are only partially underground.

Following our chat, we provide a free quote for your basement conversion During construction, our project manager will liaise with any other professionals involved in the design, planning, and project execution from start to finish. We can also recommend architects and interior designers with specific experience in basement conversions if you don't already have these professionals involved.

What We Do

From major construction projects to small building works, our experienced Builders can take care of all your building needs.

Looking for a new home? Why not build one! Get the dream home you really want, with a custom-designed New Build house development project.

Growing family? A new Extension can improve your existing house layout and increase living space, without the need to move home.

Create an extra bedroom with ensuite shower room, or a games room in your unused attic space, with a Loft Conversion customised to your needs.

Our basement conversion specialists will convert your cellar into a habitable living space customised to your needs.

Modernise and improve the comfort and funcionality of your home, while also increasing its market value, with a full Refurbishment.

Our Roofers can handle all of your domestic and commercial roofing installations and repairs—hipped, pitched, flat roofs, gutters, soffits & fascias.

Our Glaziers provide all types of new & replacement double or triple-glazed window & doors in all types of material (timber, metal, UPVC, composite) and styles.

Our Electricians handle all your electrical needs—from sockets to rewiring, domestic appliance installations + 24-hour emergency electrician cover.

Our professional Painters & Decorators will ensure your property is finished to the highest standard.

Our Kitchen Fitters can upgrade your existing kitchen, or design and install a new dream kitchen for you.

Our Bathroom Fitters can upgrade your existing bathroom, or install a new bathroom shower or wet room for you.

Our Gas Safe Plumbers handle all your kitchen & bathroom plumbing, and 24/7 emergency plumbing repairs.

Our boiler and central Heating Engineers are fully HVCA qualified and Gas Safe registered.

Our Drainage Contractors can deal with any blocked or slow-moving drains, both inside and outside.

Not just windows & doors—our Carpenters & Joiners can build bespoke furniture to your exact needs.

Our Garden Services team provide landscaping and regular garden maintenance for residential and commercial properties across London.

Our Handyman Team undertake the ‘to-do’ list you've been meaning to complete for ages, but never got around to.

basement livingroom bar
a well-lit basement tv room with large cinema / home theatre style TV
a basement living / gamesroom with staircase to upper floor and a bar area
bvl certifications

Ready To Start?

Building Vision London are Federation of Master Builders members, and fully accredited with all industry professional bodies. Our electricians, plumbers & heating engineers are City & Guilds BS7671 Level 3 qualified and certificated and Gas Safe Registered—in accordance with industry regulations.

Don't hesitate to get in touch with our friendly team. We'd be delighted to discuss your building construction and maintenance needs, offer free advice and suggest a few options. To find out more, give us a call on 0203 302 6361 or 07871 647667. Or to request a free no-obligation quote, email us below.

0203 302 6361 GET A QUOTE