What is the party wall? – The party wall is the wall that your property shares with your neighbours, either semi detached (one shared wall) or in a terrace (two shared walls). Garden walls and excavations within three or six metres of the party wall are also included in any party wall agreement.

Starting the party wall process: obtaining permission – Before you can start work on your basement, you’ll need to get written agreement from all adjoining neighbours, one month before excavation is due to begin. At this point, it’s crucial to sit down with your neighbours and talk through any issues they may have with the proposed plans and try to come to an agreement.

Serving the notice is a straightforward procedure and there are standard forms available for free, or you can agree with your neighbours to use a surveyor, who will charge a small fee to serve notice on your behalf.

The party wall process timeline – Day one: you serve notice, from which point you have one month to start the excavation work.

Day 15: If you’re neighbour hasn’t replied to you agreeing that the work can be carried out within 14 days, they are found to have ‘dissented’, meaning they are assumed not to agree. If you enter this process, you’ll need to send another letter and ask them to appoint a surveyor within 10 days or you’ll appoint one on their behalf.

Day 26: hopefully your neighbour has agreed to appoint a surveyor, otherwise you’ll have to appoint one and pay all their costs. Remember, this surveyor cannot already be involved, as they must remain neutral throughout the process.

Day one plus 1 month: work begins on the project

Day one plus 12 months: work must start by now or you have to start the process again

Common mistakes in the party wall process – If you live next to a block of flats or a house of multiple occupancy, you will have to notify everyone in the property. Check ownership via the Land Registry.

Make sure you outline the proposed work fully to your neighbours, as failure to do so may cause your neighbour to dissent. Finally, make sure you use the standard form of notice or appoint a surveyor, as the wrong paperwork can cause delays.

If you fail to issue a party wall notice or don’t secure a party wall award, then your neighbour or neighbours are legally entitled to take out an injunction and stop the work until the relevant paperwork is in place.

Good neighbours make good agreements – Posting a party wall notice through your neighbour’s letterbox can seem like an act of aggression to some people, so take the time to cultivate relationships with your neighbours over a cup of tea, before you start work on your basement conversion in London.