Crane oversail and airspace rights on tight sites

A tower crane jib that swings over the neighbour's land is a trespass, and planning permission does not make it lawful. That is the whole of the problem in one sentence. A crane oversail agreement is a private licence negotiated with the adjoining owner, and on a tight urban site it needs to be in hand before the lifting strategy is fixed, because the alternative is a court injunction at the worst possible moment in the programme.

Oversail is a property matter before it is a planning one

A landowner's rights extend into the airspace above the land to the height necessary for the ordinary use and enjoyment of the land and the structures on it. Swinging a crane jib through that airspace is a direct trespass, and the courts have granted injunctions to stop it: the leading decision on crane jibs over adjoining land, Anchor Brewhouse Developments against Berkley House, established that the oversailing itself can be restrained whether or not any damage occurs.

Two consequences matter commercially. The neighbour does not have to show harm, which removes the argument that a jib passing 20 metres above a flat roof affects nobody. And the usual remedy is an injunction rather than damages, which means the neighbour can stop the work rather than be compensated for it.

That gives an adjoining owner a strong negotiating position, and the position strengthens the later you leave the conversation. A developer whose crane is already erected is negotiating from a position everybody in the room understands.

The remedies a neighbour actually has

Set out plainly, so that the risk can be priced.

• A prohibitory injunction preventing the oversail, which can be sought urgently.
• Damages for trespass, which in practice are negotiated rather than assessed.
• An injunction requiring removal where a structure encroaches permanently.
• A claim in nuisance for consequential effects such as dust, noise or loss of light, separate from the trespass.

Nothing in the Party Wall etc. Act 1996 authorises oversail. A party wall award deals with notifiable works to and near the shared structure, and an owner who has served notices and obtained an award still has no right to swing a jib over the adjoining land. Mixing the two is a common and expensive error.

Negotiating the licence

An oversail licence is a commercial agreement, and the terms are more detailed than people expect. What a competent neighbour's solicitor will ask for, and what you should offer before they do:

The free slewing point defeats many draft licences. A tower crane out of service must be left able to weathervane into the wind, so a licence that permits oversail only between eight and six, and forbids it overnight, is unworkable and both parties need to understand why before it is signed.

Offer a schedule of condition without being asked. It costs little, it reassures the neighbour, and it protects you from claims about cracks that predate your site. The same logic applies to the pre-works records discussed in our note on demolition and asbestos surveys in the planning submission.

Where planning conditions control crane position

Planning does not grant oversail rights, but it does regulate the crane in several ways.

Conditions requiring a construction management plan are standard on constrained sites, and the approved plan commonly fixes crane position, base location, hours of lifting, lifting over the public highway, hoarding lines and delivery arrangements. Breaching the approved plan is a breach of condition, so do not submit a plan showing a crane position that depends on a licence you have not obtained. Put the crane envelope and the oversail requirement in the Construction Management Plan, with the position shown on a drawing.

Where deliveries and lifting affect the street, the transport side is dealt with separately in the Construction Traffic Management Plan, including any temporary lane closure for crane erection and dismantling, which needs the highway authority's agreement in its own right.

Height matters too. Where the site lies within an aerodrome safeguarding zone, the crane's height and position have to be agreed with the aerodrome operator and aviation warning lighting may be required, and that agreement takes time.

Highway and rail proximity

Two neighbours have statutory muscle rather than merely private rights.

Over a public highway, section 178 of the Highways Act 1980 prohibits placing or maintaining any beam, rail, pipe, cable, wire or other apparatus over a highway without the highway authority's consent. Highway authorities grant consent on terms, and those terms generally prohibit carrying loads over the carriageway or footway while open to the public, which drives the sequencing of lifts and sometimes requires temporary closures.

Beside an operational railway, the infrastructure owner's asset protection process governs. Expect a formal agreement, an exclusion zone, a prohibition on oversailing the railway with a load, slew limiting where the geometry allows, method statements reviewed in advance, and a long lead time. Any work that could foul the line is planned around possessions, which are booked months ahead.

Both regimes sit on top of the health and safety duties under the Lifting Operations and Lifting Equipment Regulations 1998 and the Construction (Design and Management) Regulations 2015, which make crane selection and lift planning a designer and principal contractor responsibility rather than a crane hirer's.

Alternatives that avoid oversail

Worth testing early, because the least costly licence is the one you do not need.

1. A luffing jib crane, which can be parked at a steep angle and has a smaller out-of-service radius than a saddle jib.
2. A crane positioned so that the out-of-service radius falls entirely within the site, accepting a longer reach or a taller mast.
3. Mobile cranes on a lift-by-lift basis, which suits lower buildings and reduces the oversail period to defined days.
4. Mast climbing work platforms and hoists instead of crane-served access.
5. Offsite manufacture and larger, fewer lifts, which shortens the oversail window.
6. Reversing the construction sequence so the perimeter rises first and the crane stands within the footprint.

Each has a cost, and the comparison with a licence fee is a straightforward commercial exercise once the neighbour's likely terms are known. Temporary works on constrained sites interact with other site constraints as well, as covered in our note on temporary works and tree protection on tight sites.

Building the risk into the programme

The sequence that works, and the order matters:

Identify every adjoining ownership from title before the lifting strategy is chosen, including airspace interests held separately from the ground. Approach each owner early, while you still have design flexibility, with a clear description of what you need and the protections you are offering. Price the licences in the cost plan rather than treating them as a contingency. Make the crane strategy in the construction management plan consistent with the licences you expect to hold. And diarise the licence expiry against the programme, because an overrun converts a licence into a negotiation.

Where a neighbour refuses outright, the answer is a design change rather than a gamble. An injunction obtained in week three of a tower crane's life costs more than every alternative on the list above. Our note on crane oversailing third party land covers the negotiation itself in more detail.

Enter your postcode on PlanScope to see which construction stage documents a constrained site is likely to need, then get the oversail licences moving in parallel.

This is general guidance, not legal advice. Oversail is a private property matter with remedies including injunctions, so take advice from a solicitor and your principal designer before relying on it.