The case of Gorst v Knight  looked at whether the tenant could extend the flat by excavating downwards and increasing the height of a 5 foot cellar. In this case if the subsoil was part of the tenant’s demise, the landlord could not unreasonably withhold consent to the alterations under the terms of the lease, but if not they had complete discretion to refuse.
Freehold land ownership usually includes the airspace above the property and the land beneath the surface but the situation is different with leasehold land, as there are no presumptions and the extent of the demise will depend on the definitions within the lease and the way that it is drafted. Here the Court was also keen to emphasise that it may be necessary for the subsoil and foundations to be treated differently from the airspace given the need for them to support the building.
The Court found that although “the foundations and the void or cellar below the ground floor” were specifically included in the detailed description of the demise, the lease used language that indicated that the subsoil itself was not included. This was supported by the fact that the landlord reserved rights for passage of services through the service conduits beneath the demise and to repair the foundations if the tenant did not do so. As the extension therefore required works to be carried out outside of the demised property the landlord had no obligation to act reasonably and was free to refuse consent.
This is yet another example of the need for a lease to be clearly drafted and for a detailed description of the demise itself to be included, specifying how far the demise extends above and below ground. In particular this will be especially important if there is any scope for future development or expansion. Our experienced Commercial Property team are used to dealing with these situations.