• Ownership of freehold land will normally carry with it such airspace above it as is necessary for the ordinary use and enjoyment of the land and the structures on it
  • Different principles may apply to leasehold land, where the scope of the demise will be determined by the terms of the lease  
  • Leases which include airspace should be carefully drafted to ensure that the height of the demised airspace is defined  

In central London, space is at a premium. Homeowners who need more room may prefer - particularly in the current climate - to extend, rather than to move.

One might imagine that the potential for expansion to a sixth floor flat was limited. However, this is what happened in Rosebery Ltd v Rocklee Ltd.

A block of flats had eight storeys. The block narrowed at the sixth floor, so that the flats on the first to fifth floors projected further than those above them. The result was that the tenant of a sixth floor flat had a flat roof outside its flat - the roof of the fifth floor flat below. The tenant of the sixth floor flat obtained permission from the landlord to build an extension, in the airspace above the fifth floor flat. It was granted a lease of the airspace (the additional lease), and the extension was duly built.

The owner of the seventh floor flat above subsequently obtained a lease from the landlord of the roof of the sixth floor extension. It maintained that this was done to preserve its privacy, as the bathroom window of the seventh floor flat overlooked the new roof.

The sixth floor flat-owner argued that its additional lease demised not only the airspace up to the height of the sixth floor flat, but also the airspace above that, including that which adjoined the seventh floor flat. The effect would be that the sixth floor flat-owner would be entitled to use the roof of its extension as a roof terrace, or even (subject to landlord's consent) build on it. Alternatively, argued the owner of the sixth floor flat, even if the demise of the additional lease was restricted vertically to the height of the sixth floor flat, it still owned the roof of the extension which had been built. On that basis, neither the landlord nor the owner of the seventh floor flat would be able to use it, and the lease to the seventh floor flat-owner could only take effect in reversion.

The court therefore had to decide what was demised by the additional lease. The property was described as "the terrace adjoining [the sixth floor flat]". The plan attached to the additional lease identified the footprint of the terrace but did not give any indication of how far the space extended vertically.

Airspace above the extension

The court ruled that there is no presumption that a lease which includes a roof will extend upwards to the full height of the airspace available to the landlord. It held that the additional lease did not extend to the airspace above the roof of the sixth floor extension. This was because:

  • The natural expectation, where a sixth floor terrace is added by a supplemental lease to a sixth floor flat, is that it will occupy only the sixth floor, and not (unless otherwise specified) upper floors
  • The inclusion of the additional air space would have been unusual in a building of that kind. It would have been of great practical and commercial importance to both parties and, as such, the parties to the lease would be likely to spell out expressly (if it were the case) that additional airspace was to be included  
  • The description of the demised premises was the terrace "adjoining" the sixth floor flat. The airspace from the seventh floor upwards could not be said to adjoin the sixth floor flat  
  • The sixth floor flat-owner's construction of the lease was unlikely. To permit one tenant of a block of flats the use of space outside the bathroom window of the tenant of an upper floor would be likely to lead to trouble, and was unlikely to have been intended by a responsible landlord.

Roof of the extension

The court ruled that the roof of the extension would become part of the freehold. The question was whether it was also to be part of what was demised under the additional lease. The court noted that there were skylights in the extension roof. These precluded the building of an extension at seventh floor level. If it had been intended that the roof of the extension should be available as a terrace at that level, one would have expected to see some protection in the plans for the skylights, to ensure safety and privacy.

The court held that the natural inference to draw, where an extension is to be built by a tenant within the space demised to it, is that the whole of it is to be within the demise unless otherwise stated. The additional lease was therefore to be treated differently from the lease of the fifth floor flat below, where the roof was part of the original structure of the block of flats when it was built, and was never demised.

The court concluded that the roof of the extension was included in the additional lease, but not the airspace above it.

Things to consider

This case concerned a lease of part of a building, where tenants were effectively competing for the same airspace. However, it is just as important to consider whether airspace is demised on a letting of a whole building. A tenant wishing to erect telecommunications masts, or install air-conditioning equipment, on the roof of its building will not be able to do so as of right unless the lease includes a sufficient amount of airspace above the building. If no, or an inadequate amount of, airspace is demised, the tenant will have to negotiate with the landlord for additional rights - which may well come at an additional cost.

The court's decision that the roof of the extension was nevertheless demised to the tenant may lead to difficulties when repair work is required to the remainder of the building's roof, as the landlord will no longer have control over all exterior surfaces.