Why these projects are different
Most party wall jobs involve cutting into a wall. Basements and underpinning involve removing the ground that supports a neighbour’s building. Done well, nothing happens. Done badly, cracks open, doors stop closing and drains break. So surveyors, structural engineers and contractors give these projects more attention than any other, and the award is longer and more detailed.
Which notices
| Work | Notice |
|---|---|
| Excavating a basement, cellar or deep trench near a neighbour’s building | Section 6, one month |
| Underpinning a party wall, or thickening or raising it | Section 3, two months |
| A new retaining wall on the boundary | Section 1, one month |
A basement under a terraced or semi-detached house often needs both a Section 6 and a Section 3 notice, because the party wall is underpinned as well as the ground being dug beside it. Serve them together.
What the award usually covers
For basement and underpinning work, the award normally goes well beyond working hours. It can include:
- a schedule of condition of the neighbouring property, inside and out
- the engineer’s design and method statement, reviewed by the surveyors, including the sequence in which sections are dug
- temporary support to the neighbour’s wall, floor or chimney where needed
- monitoring, such as crack gauges and level readings, with agreed trigger levels and what happens if they are reached
- access to the neighbour’s property for inspection and monitoring
- insurance and security for expenses, so that money is there to put things right if it is needed
- working hours and arrangements for deliveries and spoil removal
- who pays, including the neighbour’s surveyor and engineer where reasonable
Planning and building control
Some London boroughs have specific basement planning policies and require a detailed assessment before they will grant permission. Building regulations approval is also needed. These are separate from the Act, and the party wall process runs alongside them. Do not wait for planning to finish before thinking about the Act. A Section 6 notice can be served once your drawings are settled.
Timetable
The notice periods are the same as for any other job: one month for a Section 6 notice and two months for a Section 3 notice. What takes longer is the award, because the surveyors review the engineer’s design and agree the monitoring before anything is dug. A straightforward award takes four to six weeks in our experience, and basement awards often take longer. So serve the notices as soon as the engineer’s drawings are settled. The usual order is:
- The drawings and the engineer’s design are settled, and the notices are prepared.
- The notices are served and the notice period runs. The neighbour responds, surveyors are appointed and the neighbouring property is recorded.
- The award is agreed, usually after the surveyors have reviewed the engineer’s method.
- The 14-day appeal period passes, and then work can begin.
Complex jobs, or neighbours who are slow to engage, take longer.
If you are the neighbour
Do not be alarmed, and do not consent without advice. Ask for the engineer’s drawings and method statement, appoint your own surveyor if the work is deep or close, and make sure the award includes monitoring, access for you to see the readings and a clear route if damage occurs. The building owner normally pays for all of this. See help for neighbours.
What it costs
A basement award is priced by the scope of the works, so we give you a fixed-price quotation in writing after seeing the drawings. Our published fees start at £70 for a notice and £350 for a schedule of condition, with awards from £600 and no VAT. See our fees or call 0800 999 1947.
Basement and underpinning questions
Can my neighbour stop me building a basement?
Not through the Party Wall etc. Act 1996. The Act decides how the work is done and protects their property. Whether a basement is allowed at all is a planning matter.
How close to my neighbour’s house can I dig?
The Act sets no fixed minimum distance. It sets thresholds for notices, which are digging deeper than their foundations within 3 metres, or cutting the 45 degree line within 6 metres. How close the work can safely be is for the structural engineer, and the award records the safeguards.
Who pays for monitoring and the engineer?
As a general rule the building owner, because the safeguards are needed because of their work. The award sets out the arrangements, and the adjoining owner’s reasonable costs of checking them are normally paid by the building owner too.
Do I need a notice to underpin my own house if it is detached?
If the excavation is within 3 metres of a neighbour’s building and deeper than its foundations, or within 6 metres and cuts the 45 degree line, yes, even though the house is detached. If your house is far enough away, the Act may not apply, but ask us to check.