Designing to Avoid the Party Wall Act

Saturday, 11th November 2023 | by: Justin Burns

Owners wishing to extend or alter their home often see the Party Wall Act as a bit of a headache or an opportunity for the neighbours to interfere with their plans.  The Act is actually designed to facilitate building works by conveying rights on owners allowing them execute certain works but sometimes it doesn’t feel like that to an owner who has a deadline to meet and is being delayed by their neighbour’s over officious surveyor.

One option for such an owner would be to design the works so that they fall outside the scope of the Act but that’s not as easy as it sounds. In case you’re not aware, works falling within the scope of the Act are set out in sections 1, 2 & 6 and can be summarised as follows:

  1. New walls either up to or astride the boundary with adjoining land (Section 1).
  2. Work directly affecting an existing party structure including cutting in, cutting away from, raising, underpinning and exposing it to the elements (Section 2(2)).
  3. Excavation within 3.0m of a shared or adjoining structure which is also deeper than the base of the foundations to that structure. That distance increases to 6.0m for very deep excavation (Section 6(1) & (2)).

So let’s look at how feasible it is to avoid having to serve notice for each section:

New walls

A new party wall can only be constructed with the agreement of both owners, which is understandable, but owners are sometimes surprised to discover that a notice still needs to be served if the proposed wall is on their own land but has been positioned up to the boundary to maximise space.

This is a good example of how the Act benefits building owners as walls up to the boundary are only included as they can’t be easily built without access. The need to serve notice can easily be avoided by keeping the wall back slightly, even by 50mm, but that will also remove the building owner’s right of access. Also, even if the need to serve a notice to cover the wall is circumvented, the foundations to that wall may still be covered (see below).

Party Structures

One of the most common types of work covered by this section of the Act is cutting pockets in a party wall so that beams can be inserted as part of a loft conversion. The beams typically support the floor to the loft rooms and the roof of the rear dormer.

One way to avoid serving notice would be to run the floor beams from front to rear rather than side to side and then use columns to support the beam above but that’s easier said than done. Beams running from front to rear will generally be longer and will therefore either have to be larger or have intermediate support (perhaps by a load bearing cross wall). Also, if there are chimney breasts against the party wall, the beam will have to be set back from it and there will be voids between the chimney breasts to fill in (without drilling in to the party wall).

Adjacent Excavation

The depth of new foundations vary and the shallowest type of foundation will be a reinforced concrete raft. While a raft will probably be shallower than a neighbour’s traditional mass concrete foundation it is also more expensive to design and construct so any saving in party wall costs may be eaten up.

I was involved with one rear extension project where the owner was so keen to avoid serving notice that they used a cantilevered beam encased in the foundation to the opposite side of the rear wall and then spanned a further from there across to the original rear wall of the house. An ingenious idea, but as it avoided the need to serve a Notice of Adjacent Excavation, I was not involved to see whether it could actually be built.

The common theme with many of these design innovations to avoid serving notice is that they are more expensive than the standard method to implement and may therefore be a false economy.

Finally, there is one type of work which an adjoining owner can prevent as it requires their express consent – constructing reinforced foundations that project on to an adjoining owner’s land including to underpin an existing party structure. How to circumvent this requirement was the subject of a landmark case for party wall surveyors and turned on the difference between a foundation and a downward extension to a party structure but that’s one for a future post.

If you live in the Cambridgeshire or north Essex area and require advice on party wall matters you’re welcome to contact us on 01799 543532 or via email.

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