Party Wall Agreement Explained: What It Means for Your Loft Conversion
If your work affects a shared wall or boundary, you may need a party wall agreement to stay within the law and avoid costly disputes.
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If your work affects a shared wall or boundary, you may need a party wall agreement to stay within the law and avoid costly disputes.
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A party wall agreement is a legal document between neighbours who share a wall or boundary. It's required under the Party Wall Act 1996 when building work could affect the structure you both share.
This includes common loft conversion jobs like raising rooflines, installing steel beams, or cutting into a party wall. It also applies to extensions and basement projects.The agreement sets out the planned work, how it will be carried out, and how any risk or disruption will be managed. If your neighbour doesn’t consent, surveyors will step in to create a formal document called a party wall award.
In this guide, we’ll explain when you need one, what it costs, and how to handle the process with confidence.
You may need a party wall agreement if your loft conversion affects a shared wall or boundary with a neighbouring property.
This usually applies when:
You typically won't need an agreement for a Velux loft conversion, as these projects avoid major structural changes.
It's important to check early in the planning process. If an agreement is required, you’ll need to serve notice and allow time for consent. To explore the options available, see our guide to types of loft conversions.
If your loft conversion affects a shared wall, ceiling or boundary, you’ll need to follow the steps set out in the Party Wall Act 1996. The process is there to protect both you and your neighbour. Here’s how it works.
Start by serving written notice to any neighbour whose property shares a party wall or boundary affected by the work. The notice should explain the type of loft conversion planned, the part of the structure it will impact, and when the work is expected to begin.
You must give at least two months’ notice before starting construction.
Once the notice is received, your neighbour has 14 days to reply in writing. If they agree, you’re free to go ahead. If they refuse or don’t respond, it counts as a dispute, and surveyors will need to get involved.
Even if relations are good, always get written confirmation. Verbal agreements don’t offer legal protection.
If there’s a dispute, you must appoint a qualified surveyor. Your neighbour can use the same person or choose their own. Surveyors act independently to assess the work and fairly protect both parties.
They’ll review your plans, inspect both properties and ensure everything complies with the law.
The surveyor will then produce a legal document known as a party wall award. This outlines the work that can be done, how it should be performed, and the measures that must be taken to protect each property.
It often includes a schedule of conditions, which records the state of your neighbour’s home before work begins.
Once you’ve received written consent or the party wall award is in place, you can start the build.You must follow the agreement exactly. That means working within permitted hours, sticking to the approved plans, and taking care to avoid disruption or damage.
The cost of a party wall agreement can vary depending on the scope of your loft conversion and how your neighbours respond. In most cases, you’ll need to cover the fees for a surveyor, and sometimes more than one if there’s a dispute.
Here’s a breakdown of the costs involved.
The homeowner carrying out the work usually covers all surveyor fees, even if more than one is involved.
Yes. If your neighbour doesn’t give consent to the works, a dispute is triggered. This means both parties will need their surveyor, which can double the cost. In some cases, a third surveyor may be appointed to assist in resolving the matter.
To avoid this, talk to your neighbours early. Show them your plans, offer to answer questions, and consider appointing a surveyor you both trust. Clear communication upfront can save time, money, and stress in the long run.
A party wall award is a legal document prepared when neighbours don’t agree to proposed building works. It’s drawn up by a party wall surveyor and sets out exactly what work can go ahead, how it should be carried out, and what steps must be taken to protect both properties.
It includes details such as working hours, access arrangements, and procedures for handling any damage. Once agreed, the award is legally binding and ensures the project can move forward fairly for everyone involved.
Thinking about a loft conversion but unsure how party wall agreements work? Here are the answers to the most common questions homeowners ask. We’ve kept it simple, accurate and straight to the point.
Not always. If your loft conversion affects a shared wall or boundary, like installing steel beams, building a dormer, or raising the roof, then yes, you’ll usually need one. Velux-only conversions that don’t alter the structure generally don’t require it.
You must give your neighbour at least two months’ notice before starting work. If they consent quickly, the process is straightforward. If a surveyor is needed, allow a few extra weeks to agree and issue the party wall award.
No. If your work falls under the Party Wall Act and you build without consent or an award, your neighbour could take legal action. This can lead to delays, fines, or even necessitate the reversal of the work. Always follow the proper process first.
A party wall notice is the formal written notice you serve to your neighbour before starting any work. If they don’t consent, a surveyor will be appointed to issue a party wall award, a legal document that outlines how and when the work can take place.
If you're carrying out the work, you usually pay for all surveyor fees. That includes your neighbour’s surveyor if they choose to appoint their own. It’s considered part of the cost of the project.
Yes, if your loft conversion affects a shared wall, boundary, or involves deep foundations, the law requires you to serve notice and, if needed, secure a party wall agreement or award before starting work.
If you plan to excavate within three metres of your neighbour’s foundations and your work will go deeper than theirs, you must serve a party wall notice. This often applies to projects involving new footings or heavy structural work.
A shared wall becomes a party wall when it separates two properties and is owned by both parties. Internal walls within your own home are not party walls. The key factor is joint ownership across a legal boundary.
