Party Wall Agreements and Loft Conversions: What You Need to Know

Catherine Allen
May 17
3 min read

If you’re planning a loft conversion in a terraced or semi-detached property, chances are you’ll need a party wall agreement.

At The Loft Build Company we guide clients through the full process from early design right through to legal compliance, including whether or not a party wall agreement for a loft conversion is required. Let’s break down what it is, when you need one, and how to handle the process smoothly.

What Is a Party Wall Agreement?

A party wall is a shared wall between two properties. In the context of loft conversions, this usually refers to the wall between you and your neighbour in a terraced or semi-detached house. A party wall agreement is a legal document required under the Party Wall etc. Act 1996, which governs how works affecting a shared wall must be notified and agreed upon. It protects both you and your neighbour from disputes by outlining the scope and method of work.

When Do You Need a Party Wall Agreement for a Loft Conversion?

You’ll typically need a party wall agreement if your loft conversion involves:

Cutting into the party wall to insert steel beams for the new floor
Raising or extending the wall (as in a mansard or dormer conversion)
Altering the thickness or structure of the wall in any way

So, if your project includes structural alterations to the shared wall then you must legally serve notice on your neighbour. If they consent, you can move forward. If they dissent or do not reply within 14 days, you’ll need to appoint a party wall surveyor to put together an agreement.

Can You Do a Loft Conversion Without Touching a Party Wall?

Yes, in some cases. For example, if you’re completing a Velux loft conversion that doesn’t require steel beams or changes to the party wall then you may not need a party wall agreement. However, in most structural loft conversions - including dormers, mansards and hip-to-gable designs - support beams typically rest in the party wall. In these cases, a party wall agreement is almost always necessary.

It’s always best to check early. At The Loft Build Company we’ll assess your plans and let you know whether a party wall agreement is needed, then guide you through the process.

What’s Included in a Loft Conversion Party Wall Agreement?

While each case is different, a standard agreement usually includes:

A schedule of condition of your neighbour’s property (to avoid disputes later)
Details of the proposed works
Method statements explaining how the works will be carried out
Agreed access for surveyors or builders, if necessary
Timelines and working hours

While there’s no official government-issued loft conversion party wall agreement template, your party wall surveyor will produce the correct documentation for your project.

How Long Does It Take?

Once you’ve served a party wall notice your neighbour has 14 days to respond. If they agree, you can proceed. If they object or fail to reply, a surveyor must be appointed. The whole process can take between 4–8 weeks depending on cooperation between parties.

This is why we recommend starting the party wall process as early as possible in your loft project. We’ll help you do this right after your design is confirmed.

What If There’s a Dispute?

If your neighbour dissents, then each party appoints their own surveyor (or agrees to use one jointly). These surveyors will assess the work and agree on how it can be done safely. Once an award is in place, you can legally proceed.

You can read more about your rights and obligations under the Party Wall etc. Act 1996 via the UK Government Planning Portal.

How The Loft Build Company Can Help

Our team has managed hundreds of loft conversions across London and Surrey including plenty that required party wall agreements. Emmet and the team will handle:

Identifying if your build needs an agreement
Recommending trusted party wall surveyors
Coordinating documentation and notices
Liaising with neighbours and their surveyors

We take the stress out of the process so you can focus on creating your dream space.

Learn More

Need help with a party wall issue? Get in touch for no-obligation advice today.