Who Owns the Subsoil under a Maisonette – Leaseholder or Freeholder?

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English law presumes that landowners also have title to the air above their properties and the subsoil beneath them, right down to the centre of the earth – but what happens if a property is horizontally divided into two or more units? The High Court considered that issue in a guideline decision concerning an urban maisonette.

The maisonette was located on the ground floor of a terraced house and included a basement. The property’s long leaseholders had obtained planning permission to extend the basement downwards by four feet so as to create a habitable space. However, the property’s freeholder, who also owned the upstairs maisonette, objected on the basis that the lease did not extend to the subsoil under the house. The freeholder’s arguments succeeded before a judge.

In ruling on the leaseholders’ appeal against that ruling, the Court accepted that, when the lease was signed, the freeholder owned both the air above the house and the subsoil beneath it and was thus able to demise the latter to the leaseholders. The difficulty in deciding whether such a demise had in fact been made lay in the fact that the house had been divided horizontally, rather than vertically.

In dismissing the appeal, the Court noted that, in defining the demised premises, the lease referred to the ground floor, cellar and foundations of the building, but not to the underlying subsoil. The freeholder also reserved the right to run services and conduits through and under the maisonette and that implied that the demised premises had a lower limit.

On a true interpretation of the lease, the leaseholders’ rights did not extend to the subsoil and, however desirable the basement development might be, they could not proceed with the project without the freeholder’s permission. The latter was entitled to claim compensation in return for granting any such permission.

Gorst & Anr v Knight.

Felix Clarke