Does the Party Wall Act apply to your work, and which notices do you need?

What this checker is doing

It follows the law on party walls and on adjacent excavation, section by section, in the order the questions arise: the Party Wall etc. Act 1996.

1. Does the Act cover the work? Three kinds of work are covered. A new wall at the line of junction, the boundary line between the two properties, where nothing is built at the line, or only a boundary wall that is not a party fence wall or the outside wall of a building (section 1). Work to an existing party structure, a wall or floor shared between buildings, or to a party fence wall, a garden wall astride the boundary, including underpinning, thickening or raising it (section 2(2)(a)), demolishing and rebuilding it (section 2(2)(b) and (e)), cutting into it (section 2(2)(f)), cutting away a chimney breast or other projection (section 2(2)(g)) and cutting in a flashing, the waterproof strip at a joint (section 2(2)(j)). Adjacent excavation, digging near a neighbouring building or structure (section 6). Minor work such as plastering, wiring, sockets and drilling for shelves is not on the list, and the government's guide says it needs no notice.
2. The 3 metre and 6 metre tests. An excavation within 3 m of any part of the neighbouring building or structure, measured horizontally, is covered if any part of it within those 3 m goes lower than the bottom of their foundations (section 6(1)). Within 6 m, an excavation is covered if any part of it meets a line drawn down at 45 degrees towards it from the bottom of their foundations at the face of their wall (section 6(2)). On level ground that line is as far below their foundations as it is from their wall: with foundations 1 m deep, an excavation 4 m away is caught if it goes 5 m deep or more. The owner of every building or structure within those distances is an adjoining owner for these rules, not only the owner next door (section 6(4)).
3. The minimum notice. A line of junction notice, for a new wall at the line of junction: at least one month before the work starts (section 1(2) and (5)). A party structure notice, for work to a party structure: at least two months before (section 3(2)(a)), or sooner if the adjoining owners and occupiers consent in writing (section 3(3)(a)). A notice of adjacent excavation: at least one month before (section 6(5)). An adjoining owner served with a party structure notice has one month to reply asking for extra work, in what the Act calls a counter notice (section 4(2)(b)).
4. If the adjoining owner does not reply. It depends on the notice. For a wall astride the line of junction, if the adjoining owner does not consent within 14 days, you may build it only wholly on your own land, at your own expense. That is not a dispute (section 1(4)). For a party structure notice or a notice of adjacent excavation, no consent within 14 days is treated as a dispute, which is called a deemed dispute, and party wall surveyors are appointed: one agreed surveyor for both owners, or one for each owner, and those two select a third. The surveyors settle the dispute by an award (sections 5, 6(7) and 10).
5. When a notice lapses. A party structure notice or a notice of adjacent excavation stops having effect if the work has not begun within 12 months, starting on the day it is served, and is not carried on without delay (sections 3(2)(b) and 6(8)). A line of junction notice has no such rule of its own, but the right to place projecting footings and foundations under the adjoining owner's land runs from one month to twelve months after the notice (section 1(6)).
6. Who is served, and how. Serve every adjoining owner, as the Act defines owner: anyone receiving, or entitled to receive, rent or profits from the property; anyone in possession of it, other than a mortgage lender, a tenant from year to year or for a shorter term, or a tenant at will; and a buyer under a contract to buy, or under an agreement for a lease, other than a tenancy from year to year or shorter (section 20). Hand the notice to them in person; post it to their usual or last known home or place of business in the United Kingdom; for a company, send it to its secretary or clerk at its registered or main office; email it only if they have said they will accept notices that way, to the address they gave; or address it to "the owner" of the named property and hand it to someone there or, if nobody is there, fix it somewhere easily seen on the property (section 15). A posted notice counts as served when it would arrive in the normal course of post (Interpretation Act 1978, section 7).
7. A common error. The government's guide says notice must be given between 2 months and a year before work starts. That is right only for a party structure notice (section 3). A line of junction notice, or a notice of adjacent excavation, needs one month (sections 1 and 6), and the 12 months is a rule about when a party structure notice or a notice of adjacent excavation lapses, not a window for serving it (sections 3 and 6).
8. Why there is no notice generator here. Notices fail on the facts, not the wording: a missed owner, a leaseholder nobody checked for, a notice sent to the wrong address, or a notice of adjacent excavation without the plans and sections the Act requires (section 6(6)). The government publishes an explanatory booklet and example letters. Parallel does not act as a party wall surveyor.