Building on the boundary line of two properties

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    The Party Wall Act:
    Building on the Line of Junction

    The Party Wall etc. Act 1996 (“the Act”) gives a building owner the right to construct a wall on the boundary line between his property and an adjoining owner’s property. Section 1 of the Act covers the details about how and where that wall can be constructed. It also states the process for notifying your neighbour about the proposed wall, and the rules concerning the use of projecting or reinforced foundations.

    The Act also covers other matters concerning compensation and payment, including who pays for the construction of the wall, whether there is compensation for any damage caused, and the rules on potential costs for the subsequent use of the wall by an adjoining owner. It also outlines the process of resolving disputes that arise whilst building on the line of junction.

    In this post, we’re going to be touching on the most prominent points of section 1 of the Act, as well other parts of the Act that are relevant when you intend on building a wall on the boundary line with another property.


    The position of the wall

    Section 1 of the Act relates solely to the construction of new walls on, or astride, the line of junction between two properties. To understand what this means, we must first determine what the difference is between on and astride the boundary. A wall built on the line of junction is one which is built up to the line of junction but wholly on the lands of one owner. Whereas if it is built astride the line of junction, it will straddle the lands of both properties, usually constructed with the centre line of the wall positioned on the boundary line.

    If a wall is built astride the line of junction, then it is deemed a party wall, or party fence wall if it is a garden wall. If built up to the boundary but entirely on one owner’s land, then the wall is not a party wall.

    Line of Junction Notices

    If you intend on building a wall on the line of junction, then you are required to serve the adjoining owner with notice at least one month before you want to start construction of that wall. The notice should indicate your intention to build the wall as well as describing the intended wall.

    This type of notice is required regardless of whether the wall is astride the line of junction or built on it but entirely on your land. At first glance, it might seem unnecessary to serve notice on your neighbour when the wall will be solely on your property, but the requirement for notifying your neighbour in this situation exists to protect them from unannounced works that might affect the legal boundary or stability of his land. Furthermore, a wall built entirely on your own land will often have projecting footings that go beneath your neighbour’s land.

    If your neighbour consents to a notice of your intention to build a wall astride the boundary, the wall will be built half on the land of each of the two owners, or in a position that is agreed between the two owners.

    If an adjoining owner does not consent to a notice requesting the wall is built astride the boundary, the wall must be constructed at your own expense, and entirely on your land.

    Payment for the wall

    The expense of building the wall should be apportioned based on who will benefit most from the wall, not from its position relative to the boundary line. The matter of who pays for the wall is one that needs to be agreed between the parties based on the circumstances at the time. This is usually quite straight forward in the case of works to construct a new building as the cost of building the wall will typically be paid by the person who benefits from the proposed building.

    A common alternate example is where after a wall has been constructed at the cost of one owner, the other owner subsequently makes use of that wall, for example by enclosing upon it to form an extension. In this situation, the owner constructing the extension would typically be required to pay the person who paid for the original construction of wall the sum of half the cost of building the area of the wall to be enclosed upon at today’s rates. Whilst this work is a party structure matter and is covered by a different section of the Act (section 2), it is useful to point out here.

    Where you intend on building a wall entirely on your land, you must compensate your neighbour for any damage caused to his property, for example, flower beds, driveways, or underground services. It is therefore prudent to record the condition of the adjoining owner’s property before commencing the works.



    Under the Act, the person building the wall has the right to construct projecting footings under the land of the neighbour’s property as are necessary for the construction of the wall. It is not entirely clear whether the requirement for the foundations to be necessary means that the building owner is not permitted to place foundations on the land of the adjoining owner if the wall could reasonably be built using eccentric foundations are constructed so that the edge of the footing is in line with the external face of the wall and does not project beyond it, subsequently creating a straight line down from the face of the wall, and this is a matter to be agreed between the parties, or their surveyors.

    In any event, an adjoining owner cannot simply refuse to allow projecting footings to be formed below their land, and section 2(2)(g) of the Act gives the adjoining owner the right to cut off such projections if necessary, however, there is no right for them to recover the costs of doing so unless those footings are special foundations are defined as any foundation that is reinforced with metal rods or bars.

    Where special foundations are proposed, express consent must be given by your neighbour to construct special foundations on their land. If no consent is given, then special foundations cannot be built.

    The matter of special foundations can be a difficult one because under section 11(10) of the Act if a person constructs special foundations under a neighbour’s land and that neighbour, later on, needs to cut away those foundations in the course of works, then they will be responsible for paying the cost of doing so. These costs apply to whoever lives at the property at the time, regardless of whether they constructed the footings or not. Therefore even if you didn’t construct the special foundations and you weren’t even aware of them due to them having been built before your moved in, you will still have to pay the cost to remove them if required to do so by your neighbour.


    Access Matters

    Regardless of whether you are building the wall up to, or astride, the line of junction, you have the right to access the adjoining owner’s land to construct the wall. This right is set out in section 8, and it states that you may access an adjacent owner’s land after the expiration of a 14-day notice, or earlier in the event of an emergency. Furthermore, it is an offence for an adjoining owner to prevent access to their property if notice has been given in accordance with section 8.



    In any matter where a dispute arises and cannot be agreed between the parties, then the process set out in section 10 of the Act should be followed. This process involves the appointment of surveyors to determine the matters in dispute and prepare a party wall award (party wall agreement) which will set out how the wall is to be constructed.

    The matters most commonly in dispute in relation to works on the line of junction are: the position of the wall, the necessity for foundations to project below the adjoining owner’s land, or issues relating to compensation for loss or damage.


    Murrin Chartered Surveyors can advise you on matters relating to building on the line of junction, or other issues connected with the Party Wall Act. For more information, or to speak to a surveyor, please contact us, or call 0207 112 88 77.

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