| Refurbishment |
Alterations to existing space below ground |
May require lowering the floor to increase head room; underpinning adjacent walls; improving ventilation and lighting. Typically involves improvements to, or new, waterproofing system; and new finishes and fixtures. |
- Adds value and desirability of property
- Additional usable space
- Addresses potential existing damp problems
- Provides opportunities for new activities in property e.g. games room/gym/storage
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Building regulations approval will be required for any works. Planning permission may be required, depending on extent of works and extended use. |
| New garden basement |
New basement adjacent to existing property, usually in a garden space |
New structure below ground, with planted green roof or terrace at garden level. Access from main house via new external covered staircase. |
- Adds value and desirability of property
- Additional usable space
- Provides opportunities for new activities in property
- Potential for natural daylight. and ventilation through roof lights
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Planning and building regulations approval required.
Likelihood of need for structural support to existing house is reduced as distance from the house increases.
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| New basement under new housing |
Basement space built as part of a new build development |
Arrangements of windows and internal and external access vary. Designed to suit current and future use requirements, site conditions, cost, and constructability. |
- Adds value and desirability of property
- Future adaptability
- Usable space for sustainable technologies and recycling
- Potentially reduces footprint of house
- Increases thermal performance
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No additional building or planning regulation requirements, provided it is included in the initial application. |
| Retrofit |
New space created through excavation below ground floor of an existing property |
Allows creation of additional space below business or homes, which benefit from staying in the same location.
Preservation of existing building possible (e.g. listed building). Underpinning works required
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- Adds value to property
- Additional space for business to develop in same location or family to expand
- Releases potential of empty property
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Planning and building regulations approval required.
Specialist work. Generally only economically viable for high land value properties
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| Deep basements |
Spaces below one storey deep |
Frequently used for car parking, plant services space, and storage below larger residential development and other uses including commercial, retail, or mixed use schemes in urban areas. |
- Building footprint and development potential optimised above ground
- Parking and space for deliveries possible
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Refer to The Concrete Centre guide 'Concrete Basements'
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