Basement Builders London

Bloom Builders are London’s specialist basement builders. We offer complete design and build packages, the full build or shell only to our London clients.

As part of our basement service, we cover:

  • The Dig - including;

    • Underpinning

    • Excavation

    • Temporary works & propping,

    • Organising skip, and hoarding licences

    • Rubbish removal

    • Conveyor belt install and licensing.

    • All labour and materials.

  • Waterproofing

    • Delta Membrane installation on floors and walls - 30 year guarantee

    • Ground water and foul water pumps with alarms and battery back ups.

  • Fit out

    • Stud walls and partitions

    • Plastering

    • Electrics and heating

    • Bathrooms and kitchens

    • Painting and decorating

    • Joinery.

  • Legal

    • Party wall awards & neighbours

    • Licence to alter and freeholder consents

    • Health and safety

    • CDM

For an instant quote on your basement project, use our instant quote tool

All our projects come with

  • Fixed Price Contracts

  • Full Project Management

  • Design & Build expertise

Contact us

Basements

In order to build a basement, you underpin the existing masonry wall or form a retaining wall in the garden to the desired depth of the basement. Once the building above and garden around is stable, the main area is excavated down and a new concrete slab is poured. The concrete box is then wrapped in waterproof membrane and a pump system is installed. Ready for fit out.

Please see our basement FAQs below:

Basements FAQs

  • A typical half basement takes around 4 month to dig out and under pin. A full basement takes around 6 months to dig and underpin. Once structurally complete, the waterproofing is installed along with a perimeter stud wall to protect the membrane, this takes around 1 month to complete. Then it is standard above ground works which could take between 2 and 6 months to complete depending on teh complexity of the project. In summary, we expect basements to take just over 6 months for a half basement and just under 12 months for a full basement, start to finish .

  • Prices for new basements are approximately £3,000 per sqm for the shell only. For a full fit out the prices are approx. £6,000 per sqm. It is worth noting that the cost of basements depends hugely on depth and current conditions of site and it could be higher or lower than these numbers.

  • Yes! Almost all houses can have basements done.

  • The biggest basement you can achieve through planning must leave 50% of the front and rear gardens unexcavated.

  • There are a few determining factors involved but most basements have a comfortable ceiling height of 2.50-2.70m

  • Our basements usually include a playroom, guest bedroom, wine rooms, media rooms and gyms.

  • If you basement design includes rooms that do not have means of natural ventilation you will require a HVAC system, mostly in the form of a recuperator or heat exchange unit to provide fresh air to the rooms.

  • The lightwells to the front and back should provide enough daylight and fresh air to the rooms, so we always aim for a depth of at least 1.2m but urge more. It may be tempting to skimp on this section but we recommend the lightwell goes to the floor level of the basement as it is very difficult and very unlikely that you will go back and lower it later but the increased height will add more light into the basement for the life of the structure.

  • We use Type A Waterproofing which is based on membranes provided by the market leader Delta Membranes. With this method the perimeter of basement will be lined with a non-permeable membrane to allow any water to be safely drained away before it reaches the internal finishes.

  • It is beneficial and cost saving to have an existing cellar, basement extensions can be built without one.

  • You can dig under your kitchen slab but you most likely will need to change your floor build up from a slab to a suspended stucture. This usually means at the very least the floor is changed which means the kitchen will have to come out and go back in again.

  • There needs to be some sort of access on the ground floor to allow removal of soil, so at the very least your front room will be affected to allow for a conveyor belt to be installed.

  • The depth of the basement (and storeys involved) is dependant on ground conditions, planning permissions and neighbouring properties. Due to changes made by London boroughs it is unliely that more than one storey will be permitted.

  • A full basement build is a very intrusive project and we recommend that our clients do not live in during the work. However we have worked with clients in the past who decided to stay in. Be aware that there will be significant dust, noise and vibration nuisance.

  • Yes, planning permission is required if you are digging out a new basement or adding new lightwells to the property. Our partner firm Malone + Pike can help obtaining the required permissions.

  • Planning permission is required for new basements as well as Party Wall Awards with your neighbours

  • You will get planning for an under garden basement if you leave 50% of the front and back gardens un-excavated.

  • Building work is covered by a 6 year warranty. The water proofing membrane comes with a 30 year product guarantee. If you wanted to insurance back these guarantees, you can do for an additional fee but it is not cheap.

  • We are covered by our standard Employer's Liability and Public Indemnity insurance whilst our specialist basement contractors are covered by specific basement insurance covering every project individually.

  • We charge a mobilisation deposit to book in the works and arrange the first weeks on site. Once the project has started we will raise fortnightly valuations based on progress on site. This way you will always be sure that your budget is monitored and you will never pay too much. The payments are split between us and our contractors.

Get in touch.

To get in touch, please fill in the form on the right or email us. Alternatively you can call 0207 585 2020 or call and whatsapp 07765 948 069. We’ll get back to you as soon as we can.