THE PARTY WALL ACT
If you are planning a building extension to your house, such as a kitchen extension, loft conversion or basement, then the works are likely to affect your neighbours. They will also very likely be governed by the Party Wall Act, a point of law that requires you give your neighbours due notice.
The key question is whether your proposed building works fall under the notifiable work description of the act:
1. Line of junction notice (Section 1); construction of a new wall at or astride the boundary, or
2. Party structure notice (Section 3); cover alterations to a party structure, or
3. Notice of adjacent excavation (Section 6); works within 3 or 6 metres of a neighbouring property and deeper than your neighbours foundations.
You need to serve a notice to your neighbour if at least one of the above relates to the building works.
you serve notice on your neighbour, seeking their consent to the works.
your neighbour must have agreed in writing to your notice, stating they consent to the works. And you can proceed with your works.
But, if they object or do not respond, a dispute has arisen in the eyes of the act. And a party wall surveyor needs to be appointed.
If they dissent you should send them another letter stating they must appoint a party wall surveyor within 10 days or you will appoint one on their behalf. (This surveyor cannot be the same surveyor you have appointed!). And a third surveyor shall be agreed by these two surveyors. Notably, the building owner shall pay for all three surveyors.
The third surveyor is only involved if the two appointed surveyors cannot agree on the party wall award. So make sure you appoint surveyors with good communication skills and a willingness to collaborate. Especially because the third surveyor's hourly rate is likely in the order of £200 to £350 per hour. And a party wall surveyor cannot be fired once appointed. They must be deemed unfit to serve, e.g. be dead or on the moon!
you and your neighbour should have agreed on either one party wall surveyor as an agreed surveyor working for both parties. Or 2 party wall surveyors plus the third surveyor.
The party wall surveyor(s) shall undertake a condition survey of the neighbour's property and draft a party wall award. This award will lay out the rules your builder will have to follow when constructing those works relating to the party wall act:
The award allows your builder to access the works from your neighbour's property and without this you would be trespassing.
And you can include the condition survey in your building contract. So in the event of any damage caused by your builder, you can hold your builder responsible for any repairs.
Finally, if the party wall award has been agreed by all surveyors (or the agreed surveyor), works can commence on day one plus one month for line of junction or adjacent excavation works, and day one plus two months for works for alterations to the party structure.