Deep Basement Excavations
The defining local project. Digging well below and close to neighbouring foundations almost always triggers the Act, usually with several notices.
Section 6Party Wall Services. Handled by Professional Surveyors.
Planning works on a Mayfair home, or just received a Party Wall Notice from a neighbour? LENIO Party Wall Surveyors handles the whole process for you.
Looking for a party wall surveyor in Mayfair? LENIO Party Wall Surveyors works across Grosvenor Square, Berkeley Square, Mount Street, Shepherd Market and Park Lane, on both sides of the wall.
This is part of our Central London coverage, and a prime party wall area of townhouses and mansion blocks. Most basements, underpinning and refurbishments here engage the Party Wall etc. Act 1996.
Most owners here ask this before a basement, underpinning or refurbishment, usually when an architect or engineer raises it. Whether you need a notice depends on the works and how close they sit to your neighbour.
This guide sets out exactly which works are notifiable, how proximity to the boundary matters, and what to do if you are uncertain.
On these prime townhouses and mansion blocks, works usually affect a shared wall or dig close to a neighbour's foundations. That is why most projects are notifiable, and the party wall notice Mayfair projects require is the first formal step. Our guide on whether you need a Party Wall Notice covers it in full.
Mayfair is as prime as London gets. Grand Georgian townhouses and mansion blocks surround Grosvenor Square, Berkeley Square and Mount Street, and many are listed. The projects here are large and carefully run.
With no room to build outward, owners build down, often several storeys. Deep basements and underpinning are the signature works, and both put serious load on neighbouring foundations.
That makes excavation the central party wall concern in Mayfair. A careful notice and record protect a very valuable neighbour.
Most Mayfair projects engage the Act through one of four works. Each triggers a different notice.
The defining local project. Digging well below and close to neighbouring foundations almost always triggers the Act, usually with several notices.
Section 6Strengthening an older townhouse's foundations is notifiable work to a party structure, especially where it adjoins a neighbour.
Section 2In a mansion block or townhouse, cutting into, thickening or altering a shared wall is notifiable work to a party structure.
Sections 2 & 3Digging foundations within three or six metres of a neighbouring building can trigger the Act, even when the party wall is untouched.
Section 6The most common mistake we see in Mayfair is assuming that, on a large scheme, the project team has already served the party wall notices. With a project manager, architect, engineer and contractor involved, the party wall step is easy to assume is in hand.
Each consultant covers their own piece. Unless a party wall surveyor has been appointed for that role, the notices may not have been served at all. The duty still sits with the Building Owner.
On a prime project, a missed notice can stop a very expensive site. We confirm the party wall position early, so it is owned by someone, not assumed by everyone.
Wherever you are in the process, LENIO Party Wall Surveyors covers it for Mayfair owners. The work breaks down into a handful of clear services, whether you are the Building Owner or the Adjoining Owner.
Working out which notice a Mayfair project needs, and serving it correctly on the right Adjoining Owners, is where the process starts. Get this step right and the rest tends to follow.
Explore Party Wall Notices →
We photograph and document the neighbouring property before anything begins. That record is what settles any question about damage later, for both sides.
Explore Schedule of Condition →
When a neighbour dissents, we draft the Party Wall Award that allows works to proceed, covering hours, access and the condition record.
Explore Party Wall Awards →
Planning the works yourself? We act on your behalf, handling the notices and running the process so your Mayfair project does not lose time.
Explore Building Owner Surveyor →
Received a notice from next door? We represent you, protecting your property and your rights, typically at the Building Owner's cost.
Explore Adjoining Owner Surveyor →
If both sides are comfortable with a single impartial surveyor, LENIO can take that role for both. It is usually faster and cheaper than two separate appointments.
Explore Agreed Surveyor →Three terms Mayfair homeowners ask about most, and what each one actually means for your project.
A Party Wall Award is the document surveyors prepare when a neighbour dissents to your notice. It sets out how the works are carried out, the working hours, access arrangements and a Schedule of Condition. You only need one if your neighbour dissents, or does not respond within 14 days. If they consent in writing, the works proceed on the notice alone.
Many owners say party wall agreement when they mean either written consent or the Award that follows a dissent. A verbal yes gives no protection. If your neighbour consents in writing, that written consent is the agreement Mayfair owners rely on. If they dissent, the Award becomes the formal agreement that governs the works.
Before works begin, a party wall survey records the condition of the neighbouring property in photographs and notes. On these listed townhouses and mansion blocks, where the dig sits close to next door, that baseline is what settles any later question about damage. Both owners hold the same record, so neither side can argue about what the property looked like before the works.
In most cases, a short look at your plans is enough to confirm whether you need a notice, which one applies, roughly how long it will take, and what happens next. LENIO Party Wall Surveyors offers this initial advice for free, with no obligation to go further. For Mayfair, that usually starts with a look at how your deep basement excavations sits relative to the boundary.
A party wall surveyor working in Mayfair earns their fee by doing more than issuing a notice. That means confirming exactly what your project requires, serving the right people, and resolving disagreements quickly enough that your start date holds.
LENIO Party Wall Surveyors is a specialist practice, led by a Chartered Civil Engineer and Member of the Institution of Civil Engineers (ICE). The lead surveyor is also a Chartered Building Engineer and Member of the Chartered Association of Building Engineers (CABE). On Mayfair deep basements, underpinning and prime schemes, that mix of engineering and party wall knowledge is exactly what the job needs.
LENIO knows the local prime stock and its major schemes well, and handles the process end to end. We keep your neighbour relationship calm while the works go ahead. LENIO is the party wall surveyor Mayfair homeowners call first.
Chartered Civil Engineer, Member of the ICE
Chartered Building Engineer, Member of the CABE
LENIO is based in central London and covers Mayfair and the wider Central London area in person. We attend for the party wall survey and the Schedule of Condition, so wherever your project sits in Mayfair, a chartered surveyor comes to you.
Call LENIO TodayParty wall matters are procedural far more often than they are adversarial. The aim is simply to carry out the works properly and protect the property next door, while keeping the relationship with a long-term neighbour intact. A specialist party wall surveyor in Mayfair takes care of that cleanly. Here that most often means deep basement excavations, so it is usually the first thing we ask about.
The downside of getting this wrong is not abstract. An invalid notice has to be served all over again. Without a Schedule of Condition, you have little to point to if damage is alleged later. And a neighbour who feels overlooked is considerably more likely to dissent and slow things down.
LENIO Party Wall Surveyors leads with a calm, reassuring approach. The first conversation is free, and once we have reviewed your drawings you will have a clear quote.
Still working through a party wall question? These guides answer the most common ones in full. Start with the one closest to your situation, or explore the full library.
Which works are notifiable, how proximity to the boundary matters, and what to do if you are uncertain.
Explore The Guide →If your neighbour dissents, your project is not blocked. The surveyor route, the Award, and how long a dissent adds.
Explore The Guide →What each one is, when each applies, and how a notice can lead to an Award, so you know which applies to you.
Explore The Guide →The timeline stage by stage, what makes it longer or shorter, and how serving notice early keeps you on schedule.
Explore The Guide →Typical fee ranges for notices and Awards, who pays, and how to keep your party wall costs down.
Explore The Guide →What it includes, when you need one, what it costs, and how it protects both sides if damage is alleged.
Explore The Guide →Yes. LENIO works across the whole of Mayfair, from Grosvenor Square and Berkeley Square to Mount Street, Shepherd Market and Park Lane. If your street is not named on this page, a quick call confirms that we cover it.
We travel to you for the party wall survey and the Schedule of Condition, as part of our Central London coverage.
Yes. A project manager, architect and engineer each cover their own role. None of them serves the party wall notices unless a surveyor is appointed for it. The duty stays with the Building Owner.
We confirm the party wall position early and act for you, so nothing is assumed and the site is not stopped.
Yes, almost always. A deep basement digs well below and close to neighbouring foundations, which triggers the Act, usually under several notices. The deeper the dig, the greater the risk.
Because of that, the Award is detailed, and a surveyor who reads the engineering is essential.
No. Listed-building consent controls the building, but it is separate from the Party Wall Act and your neighbour's rights. A party wall notice in Mayfair is still required for notifiable works.
We run the party wall process alongside your listed and planning consents, so nothing holds up the scheme.
There is no single price, because the cost depends on how your neighbour responds and how many owners are involved. A consented notice sits at the low end, while a party wall award in Mayfair, after a dissent, costs more.
LENIO gives free initial advice and a clear quote after reviewing your drawings. You will know the cost before any work begins.
Whether your own project is underway or a neighbour has just served you a notice, LENIO Party Wall Surveyors covers Mayfair and the wider Central London area. Get in touch for free initial advice and a quote built around your project. Deep Basement Excavations is the project we see most often here, so we usually know the ground before we start.