Cellars · Basements · Lower ground
Basement & cellar conversions in East London
We convert existing cellars and basements into usable rooms across East London and Essex, with waterproofing, insulation, lighting, ventilation and a full finish.
Prices
| Item | Price | Notes |
|---|---|---|
| Cellar conversion (existing cellar) | from £1,800 per m² | Waterproofing, insulation, electrics and finishes. Lowering or underpinning priced after survey. |
Starting prices. The final price depends on size and condition; we measure for free and quote in writing. We are not VAT registered, so no VAT is added to our labour; where a price says “+ VAT”, that is the VAT our supplier charges on the materials, passed on at cost.
How much does a basement conversion cost?
Converting an existing cellar costs far less than digging a new basement. The price depends on head height, how much waterproofing (tanking or membrane) is needed, whether the floor must be lowered or walls underpinned, light wells and windows, drainage and pumps, and the finish. Lowering floors and new basements need structural design, Building Regulations and often planning permission. We survey for free and give an itemised quote.
Converting a cellar or digging a basement: the difference
Many Victorian and Edwardian houses in East London have a cellar under the front room or hallway. Converting one means keeping the existing walls and floor, or lowering the floor a little, then waterproofing, insulating and finishing. Digging a new basement, or extending a cellar under the whole house or garden, is major structural work. It involves underpinning, temporary propping, a structural engineer, party wall notices to both neighbours, and usually planning permission. We are clear at the free survey about which kind of job yours is.
Keeping water out
Ground water is the main risk below ground, and the British Standard for below-ground waterproofing is BS 8102. Designers usually choose from three approaches, often combined:
- Tanking (Type A): a waterproof coating or render applied to walls and floor that holds water back.
- Structural waterproofing (Type B): the concrete structure itself is designed to resist water. Used mainly in new basements.
- Cavity drain membrane (Type C): a studded membrane lets any water that gets in run to a drainage channel and sump pump, then out. Common in cellar conversions because it copes with damp old walls.
A pumped system needs a power supply and servicing, and many people add a backup pump or battery. We explain which system your cellar suits and what looking after it involves.
Regulations for a habitable basement
Turning a cellar into a bedroom, living room or office needs Building Regulations approval. Inspectors look at the waterproofing, insulation, ventilation, ceiling height over the stairs and, most of all, fire escape. A basement room usually needs a protected route to an exit, or an escape window or door to a light well. Electrics must meet Part P. If you are lowering the floor beside a neighbour's foundations, the Party Wall etc. Act 1996 applies. Light wells at the front of a house usually need planning permission, so check with Redbridge Council or your local authority.
Light, air and use
A cellar with no windows suits a cinema room, gym, utility or storage better than a bedroom. Adding a light well or enlarging a front window makes it feel like part of the house. Mechanical ventilation keeps the air fresh and stops condensation. Underfloor heating works well because the floor is being rebuilt anyway.
How a cellar conversion runs
- Survey of head height, walls, floor, water level and access.
- Design of the waterproofing, structure and fire escape, and Building Regulations approval.
- Clearing, stripping old finishes and any floor lowering.
- Waterproofing, drainage channels and sump pump.
- Insulated floor, stud walls, electrics and ventilation.
- Plaster, flooring, decorating and a test of the pump before handover.
Areas we cover
Ilford, Gants Hill, Barkingside, Seven Kings, Goodmayes, Chadwell Heath, Hainault, Woodford, Wanstead, Redbridge, Romford, Barking, Dagenham, Chigwell, Loughton, Newham and the rest of East London and Essex.
Questions people ask
How much does a cellar conversion cost?
It depends on head height, waterproofing, any floor lowering or underpinning, windows, drainage and finish. We survey for free and give an itemised quote.
Does a basement conversion need planning permission?
Converting an existing cellar often doesn't, but new basements, light wells and lowering floors usually need planning and always need Building Regulations approval.
How do you stop a cellar getting damp?
With a waterproofing system designed to BS 8102, usually tanking or a cavity drain membrane with a sump pump, plus good ventilation. The right choice depends on the walls and the water level.
Can a cellar be used as a bedroom?
Yes, if it meets Building Regulations, which includes a safe fire escape route or an escape window, ventilation and enough head height. Cellars without windows suit gyms, cinema rooms or storage better.
Do I need to tell my neighbours?
If you lower the floor or dig near their foundations, usually yes. The Party Wall etc. Act 1996 requires notice before work starts.
Visit or contact us
SK Design & Construct Ltd, 6 Spurway Parade, Woodford Avenue, Ilford IG2 6UU. Call or WhatsApp 07774 944042 or email info@skdesignconstructltd.com. Registered in England and Wales, company number 16582978.