Who can ask for it
An adjoining owner can ask the building owner to provide security before starting work under the Act. The surveyors decide whether security is justified and, if so, how much and how it is held.
When it is usually requested
- Basements and deep excavations
- Major work to an old party wall, such as rebuilding or underpinning
- Projects where the building owner's finances or builder are a concern
- Where the property is owned by a company or developer
It is rarely requested for a typical loft conversion or extension.
How much
There is no fixed figure. The surveyors consider the cost of making the neighbour's property safe and weathertight if the work were abandoned, and of putting right likely damage.
How it is held
Usually in an escrow or stakeholder account, often with a solicitor or the surveyors, under terms set out in the award. It is released once the work is finished and any damage is resolved.
The reverse case
Where a neighbour has asked for extra work through a counter notice, the building owner can in turn ask the neighbour for security for that extra work.
Where this comes from in the Act
Links go to the official text of the Party Wall etc. Act 1996 on legislation.gov.uk.