Party Wall Agreement for Flats and Leaseholders

Richard Hourican | 28-08-2026

Flats, maisonettes and converted London houses can make the Party Wall process more complicated than a standard terraced-house extension. Even where there is no garden boundary issue, a flat may share walls, floors, ceilings, roofs, staircases, chimney structures and foundations with other owners.

This means a Party Wall Agreement for flats may involve more than one adjoining owner, more than one notice, and separate leasehold or freeholder consent alongside the Party Wall etc. Act 1996 process.

This guide explains when the Party Wall Act can apply to leasehold flats, who may need to receive notice, how freeholders and managing agents fit into the process, and what London flat owners should check before works begin.

Quick Answer: Do Flats Need a Party Wall Agreement?

Flats may need Party Wall Notices where works affect a party wall, party structure, separating floor, ceiling, shared wall, chimney structure or neighbouring foundations.

The most important point is that a flat does not need to share a garden boundary to fall within the Party Wall process. The relevant “party structure” may be above, below, beside or around the flat.

Common examples include:

• removing or altering a chimney breast in a converted house;
• cutting into a shared structural wall;
• altering a floor or ceiling separating two flats;
• inserting steel beams into a party wall or party structure;
• opening up a load-bearing wall between rooms;
• excavating below or near neighbouring foundations;
• basement works below flats or maisonettes;
• roof or loft works in a top-floor flat where shared structures are affected.

For professional advice on whether your works need notices, see our Party Wall Agreement London service.

Why Flats Are Different from Houses

A typical house may have one neighbour on either side. A flat can have adjoining owners above, below, beside, behind, below ground, or across shared parts of the building.

In London, many flats are also leasehold. This can create two separate questions:

• Party Wall Act question: does the work affect a party wall, party structure, boundary or neighbouring foundation?
• Leasehold consent question: does the lease require freeholder, landlord, management company or licence-to-alter consent?

These are not the same process. A flat owner may need to comply with the Party Wall Act and also obtain separate consent under the lease.

What Is a Party Structure in a Flat?

A party structure is wider than a party wall. In flats and maisonettes, it can include floors, ceilings, walls, partitions or other structures separating parts of a building in different ownership.

This is why works inside one flat may affect another owner even if the works do not touch an external wall.

Examples may include:

• the floor between a ground-floor flat and first-floor flat;
• the ceiling below an upper flat;
• a wall separating two maisonettes;
• a staircase wall between separately owned parts of a converted house;
• a shared chimney structure passing through more than one flat;
• a structural wall owned or used by more than one owner.

For more background, see our guide to Party Wall vs Party Structure and our Party Wall Structure Survey London service.

Who Is the Building Owner in a Leasehold Flat?

In Party Wall language, the Building Owner is the owner who wants to carry out the works. In a leasehold flat, this may be the leaseholder if they are proposing the works and have a sufficient interest in the property.

However, the leaseholder may not be the only person whose consent or involvement is needed. The freeholder, management company or other leaseholders may also have relevant legal interests depending on the works and the building structure.

This is one reason Party Wall Notices for flats should be prepared carefully. Serving only the occupier, only the managing agent, or only the freeholder may not be enough.

If you are planning works from a flat, our Building Owner’s Surveyor service can help identify who needs notice and which documents are required.

Who Is the Adjoining Owner in a Block of Flats?

The adjoining owner is not always the person who lives next door. In flats, adjoining ownership may include:

• the leaseholder above;
• the leaseholder below;
• the leaseholder next door;
• the freeholder or landlord;
• a management company or residents’ company;
• joint owners of a share of freehold;
• other owners whose property or structure is affected by the works.

The correct list depends on the lease, title, building layout and proposed works. The relevant owners for a chimney breast removal may not be the same as for a basement excavation, roof extension or structural opening.

For advice after receiving a notice, see our Adjoining Owner’s Surveyor Services.

Is the Managing Agent Enough?

Managing agents are often helpful because they hold building information and can communicate with leaseholders and the freeholder. However, a managing agent is not automatically the adjoining owner.

Before serving a Party Wall Notice, check:

• whether the managing agent is authorised to accept notices;
• whether the freeholder must be served directly;
• whether leaseholders above, below or beside must be served;
• whether a residents’ management company has a relevant interest;
• whether the building has share-of-freehold arrangements;
• whether the lease requires separate licence-to-alter consent.

Notices should be served on the correct legal owner or owners, not merely the easiest point of contact.

Party Wall Notice vs Freeholder Consent

A Party Wall Notice does not replace leasehold consent. Similarly, freeholder approval does not automatically replace the Party Wall process.

If your flat needs Party Wall Notices, visit our Party Wall Notices in London service.

Common Flat Projects That May Need Party Wall Advice

Structural alterations

Removing load-bearing walls, forming structural openings or inserting steel beams can affect a party structure. The structural drawings should be checked before any assumption is made about notice requirements.

Chimney breast removal

Converted houses often have shared chimney structures passing through more than one flat. Removing part of a chimney breast may affect a shared wall or structure and can require Party Wall Notices.

Floor works

Works that alter, cut into or structurally affect the floor between flats may require Party Wall advice. Cosmetic finishes may be different, but structural work to a separating floor or ceiling should be reviewed.

Basement excavation

Basement work in or below a converted building can involve excavation near neighbouring foundations, underpinning and works to party structures. These projects often need careful surveyor input.

See our Party Wall Survey for Basement Works London service.

Top-floor loft or roof works

Loft conversions and roof-level alterations in top-floor flats can raise complex questions about ownership of the roof void, structural rights, lease terms and Party Wall requirements.

What Happens After a Notice Is Served?

After a Party Wall Notice is served, each adjoining owner can usually:

• consent in writing;
• dissent and appoint their own surveyor;
• dissent and agree to use one Agreed Surveyor;
• fail to respond, which may lead to a deemed dispute depending on the notice type.

If a dispute arises, surveyors may agree a Party Wall Award setting out how the notifiable works may proceed.

Where the owners are comfortable using one impartial surveyor, the Agreed Surveyor route may reduce duplication and keep the process proportionate.

Why a Schedule of Condition Matters in Flats

A Schedule of Condition records visible condition before notifiable works begin. In flats, this can be particularly important because damage concerns may involve ceilings, floors, party walls, stairwells, common parts or neighbouring flats above and below.

A good record may include:

• cracks in walls and ceilings;
• movement around openings;
• condition of cornices, plaster, tiles and finishes;
• water staining or damp marks;
• floor and ceiling condition;
• common parts where relevant;
• photographs linked to written notes.

Learn more about Schedule of Condition Surveys.

Building Owner Checklist for Flat Works

Before starting works in a flat, check:

• Does the lease allow the proposed alterations?
• Is a licence to alter or freeholder consent required?
• Could the works affect a wall, floor, ceiling, roof or party structure?
• Are flats above, below or beside affected?
• Is the freeholder or management company an adjoining owner?
• Have all leaseholders and owners with relevant interests been identified?
• Are structural drawings and method statements available?
• Are Party Wall Notices required before work starts?
• Is a Schedule of Condition recommended?

Adjoining Owner Checklist for Flats

If you receive a Party Wall Notice for works in another flat, check:

• Are you correctly named as an adjoining owner?
• Do you understand the proposed works?
• Are drawings and structural details included?
• Could the works affect your ceiling, floor, walls or finishes?
• Do you want to consent or dissent?
• Would a Schedule of Condition help protect your position?
• Should the freeholder or managing agent also be involved?
• Do you need independent surveyor advice before responding?

Common Mistakes with Party Wall Notices for Flats

Serving only the occupier

The occupier may not be the legal owner. Notices should be served on the correct owner or owners.

Forgetting the freeholder

Depending on the structure and lease, the freeholder may have a relevant interest and may also control separate alteration consent.

Assuming the managing agent is enough

Managing agents often coordinate communication, but that does not automatically mean notice has been validly served.

Ignoring the flat above or below

In flats, the most relevant adjoining owner may be above or below, not just next door.

Mixing up Party Wall consent and leaseholder consent

A Party Wall Award does not remove the need for leasehold permissions. Freeholder consent does not remove Party Wall obligations.

When Should You Ask a Party Wall Surveyor?

Ask for advice early if:

• the property is leasehold;
• the building is a converted house;
• the works affect a wall, floor, ceiling or chimney structure;
• there are flats above, below or beside the works;
• the managing agent has requested Party Wall information;
• you are unsure who should receive notice;
• the neighbour or freeholder has raised concerns;
• the project involves basement, roof, loft or structural work.

Hourican Associates can review the leasehold context, drawings and proposed works, then advise which Party Wall Notices may be needed and who should receive them.

Party Wall Agreements for Flats FAQs

Do flats need a Party Wall Agreement?

Flats may need Party Wall Notices where works affect a party wall, floor, ceiling, party structure or neighbouring foundations. The correct process depends on the works, ownership structure, lease terms and adjoining owners.

Can a floor or ceiling between flats be a party structure?

Yes. A party structure can include a floor, ceiling or other structure separating parts of a building in different ownership, such as flats or maisonettes.

Who should receive a Party Wall Notice in a block of flats?

The correct recipients depend on the building ownership and lease structure. They may include adjoining leaseholders, freeholders, management companies or other owners with relevant interests in the affected structure.

Does the managing agent count as the adjoining owner?

Not automatically. A managing agent may help with communication, but the notice still needs to be served on the correct legal owner or owners. The lease and title structure should be checked.

Does a leaseholder need freeholder consent as well as a Party Wall Notice?

Often, yes. Party Wall procedure is separate from leasehold consent, licence to alter, planning permission and Building Regulations. A leaseholder may need to comply with more than one process.

Do I need a Party Wall Notice for a flat renovation?

Cosmetic works may not need notice, but structural alterations, floor works, chimney breast removal, steel beams, works to separating walls or floors, and excavation may require Party Wall advice.

What happens if the wrong flat owner is served?

Serving the wrong person can make the notice ineffective and delay the process. Flats often have leaseholders, freeholders, joint owners and management companies, so ownership should be checked carefully before notices are served.

Planning Works in a London Flat?

Hourican Associates can review your proposed works, leasehold context and adjoining owner position, then advise whether Party Wall Notices are required and who should receive them.

Check Who Needs Notice

This article is general guidance only and should not be treated as legal advice. Party Wall requirements for flats depend on the property, ownership structure, lease terms, proposed works, adjoining owners and neighbour response. Leasehold consent, planning permission and Building Regulations are separate processes. Hourican Associates are specialist Party Wall Surveyors in London and can advise on your specific project.