Sandpit Lodge basement: APP/J1915/X/23/3329462
Sandpit Lodge, Essendon, Hatfield: appeal APP/J1915/X/23/3329462 is a useful lawful development decision on whether a new basement can fall within Class A permitted development.
The Inspector found that Class A was capable of permitting the basement and, on the particular facts, the excavation, underpinning and support works did not amount to a separate engineering activity of substance. The appeal was allowed and a lawful development certificate was granted.
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- Neutral citation
- APP/J1915/X/23/3329462
- Court
- Planning Inspectorate
- Judgment date
- 25th September 2025
- Judge
- D A Hainsworth LL.B(Hons) FRSA Solicitor
- Case number
- APP/J1915/X/23/3329462
The proposal
The appeal concerned Sandpit Lodge, a detached house in its own grounds at Essendon. The proposed works included single-storey side and rear extensions, a basement beneath the existing ground-floor rooms and a detached outbuilding.
East Hertfordshire District Council accepted the side and rear extensions as permitted development but refused a proposed lawful development certificate for the basement and outbuilding.
Can Class A permit a basement?
The Inspector considered the words “enlargement, improvement or other alteration of a dwellinghouse” in Part 1 Class A capable of permitting the addition of a basement.
He also recognised the important qualification identified in R (Michael Eatherley) v London Borough of Camden [2016] EWHC 3108 (Admin): excavation, underpinning and support can reach the point at which they become a separate engineering operation requiring planning permission.
Whether that point has been reached is a matter of fact and degree for the decision-maker in the circumstances of the individual proposal.
Why the basement was permitted development
The basement was to sit directly beneath the existing ground-floor rooms. Access would be formed by reconfiguring the existing hall and staircase arrangement inside the house.
Excavation would be necessary and the works would probably require underpinning and structural support. However, the Inspector found that they would not alter the external appearance of the house or grounds and would have no impact on neighbouring properties.
As a matter of fact and degree, he concluded that the engineering works were not an activity of substance separate from the enlargement, improvement and alteration of the house.
The appeal was allowed
The Inspector concluded that the basement was permitted by Class A. He also found the proposed outbuilding permitted by Class E, rejecting the council’s reliance on its size relative to the dwelling as determinative of whether it was required for an incidental purpose.
The appeal was allowed and a certificate under section 192 was issued confirming that the proposed operations would have been lawful on 7th April 2023.
What Sandpit Lodge means for basement projects
This decision does not establish that every basement beneath a house is permitted development. It is valuable because it demonstrates how the fact-and-degree test can operate after Eatherley.
A basement directly beneath an existing dwelling can fall within Class A where the works amount to an enlargement or alteration and the necessary engineering works are not a separate activity of substance. More extensive excavation, including works extending beyond the footprint or involving more substantial engineering operations, requires its own assessment.
For the wider planning position, see our guide to basement planning permission.
Read the Sandpit Lodge appeal decision
The complete six-page Planning Inspectorate appeal decision is hosted locally and is available to Gold Members.
Case Law Page Created: 26th September 2026