Types of basements

Basements can be broadly sub-divided into five categories, depending upon their location, time of construction relative to the main property and depth. A brief summary of the differences, and the key issues related to each is outlined below.

Type of Basement





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

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


Planning and building regulations approval required.

Likelihood of need for structural support to existing house is reduced as distance from the house increases.

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

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

- Adds value to property

- Additional space for business to develop in same location or family to expand

- Releases potential of empty property

Planning and building regulations approval required.

Specialist work. Generally only economically viable for high land value properties

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

Refer to The Concrete Centre guide 'Concrete Basements'