Firstly, without boring you with the detail, let me provide you with a brief background. The Party Wall Act (The Act) as we know it today was effectively born from the London Building Acts (LBA). As you'll appreciate London includes a large numbers of properties which are constructed in close proximity to each other, and neighbourly disputes were slowing down the construction process. The LBA introduced measures to create it easier for developers and home owners to handle work along boundary lines and reduce the level of disputes by aiming specific obligations on both parties. The LBA was used successfully in London for quite some time until finally in 1996 it had been made a decision to revamp the act and roll it out nationwide by means of The Party Wall Act 1996.
The Act is wide ranging and is necessary more than you would think. But you are not alone unless you know much about any of it. Many builders I understand either don't know about it, or worse ignore it. Professionals aren't immune either.
You're probably interested in this short article because you're going to carry out a construction project, or maybe your neighbour is. It might be a little extension or loft conversion, or something on a more substantial scale. The act doesn't consider size it only works on principal. https://canvas.instructure.com/eportfolios/2466563/Home/Exactly_what_is_a_Party_Wall is of course to determine if the act is applicable in the first place. If you are in virtually any doubt it will always be advisable to seek professional advice and in many instances the position isn't monochrome. In crude terms however, a celebration wall is a structure shared by two neighbours and this would include boundary walls or fences and also the walls to a building. Perhaps in this regard the title of the act is really a little misleading and more than this, it may also be applicable in the event that you propose to construct a wall or building on land where no wall or physical boundary currently exists.
In today's environment where most properties are in close proximity one to the other it is generally the case that the act can be applicable during any construction project that involves digging foundations close to a boundary line. It could also be applicable for loft conversions or building refurbishments where in fact the party wall is not being altered, but support is required from the wall for steel supports or suspended timber floors or ceilings etc. In tandem, it may come into play for work that you would feel is minor, such as for example cutting into a wall to insert a weatherproof detail or flashing.
As you should have deduced the act is far ranging and is generally applicable when you carry out construction work close to neighbouring buildings / land. My advice would be to consult a surveyor who has party wall experience should you be unsure. Most surveyors would be willing to give some free advice over the phone and when the project is local to them, you will often discover that they will provide you with a free visit to assess your particular project in the hope that, if the act is applicable you'll appoint them to attempt the role for you personally. Certainly in my own professional experience as a chartered building surveyor I give free suggestions about a regular basis in the hope that it'll lead to an instruction. There are surveyors who will charge regardless but the key, as always is to agree a scope of service and any fee in advance to avoid confusion. You then know predicament.
After you have deduced that the wall / structure is a party wall you should determine if the act does apply to the work being completed. The Act is approximately 15 pages long and put into 22 sections with various sub-sections. It isn't therefore an extended document and several of the sections include interpretations and explanation meaning that the most relevant sections are even more condensed. There's however two main sections which apply mostly and the house owner will be advised to understand;
Section 2: Repair etc: of party wall: rights of owner - This section sets out the rights of the owners of a party wall at the mercy of serving the correct notice. Such rights numbered from 2 (2) (a) - (2) (n) include such works as; "to make good, repair, or demolish and rebuild, a celebration structure or party fence wall" and also "to cut into a party structure for just about any purpose (which might be or include the purpose of inserting a damp proof course). The complete list is set out in the act and covers most work, other than very superficial, which could possibly be carried out to a wall. Under most circumstances where any work has been carried out directly to a shared wall, it might be expected that the act should come into play, although you can find exceptions and you will be advised to take advice.
More help which is likely to be most applicable is Section 6: Adjacent excavation and construction. Once again the technicalities are set out in the act but could be bewildering. Essentially however, if you propose to excavate within 6 metres of an adjoining party wall / structure (remembering that a party wall may be a garden wall or fence) the act may be applicable, if certain criteria relating to depth of excavation in relation to any party walls are achieved. For anyone who is excavating within 3 metres the act is more than likely applicable.
After you have determined that; a) the wall is a party wall and b) based upon the scope of work or proximity of excavation the terms of the act can be applied, it will be necessary to follow the procedures set down within the act so as to protect your position.
The first procedure would be to serve notice on the adjoining owner to see them of the task being carried out. There is no requirement to appoint a surveyor to serve these notices for you and sample templates are available online to download from various sources if you want to do-it-yourself. But if you do propose to serve notice yourself, keep an eye on the fact that much like all things where you may not have sufficient knowledge, the repercussions of getting it wrong might have legal ramifications. On this basis it is normally advised that you seek professional assistance. The notices, when served changes depending upon whether the work falls under section 2, section 6 or both (you can find other sections but as they are less commonly applicable I have not included commentary on this page), as too would be the amount of time applicable between your notice being served and work commencing. The notice under section 2 provides two months notice and the notice under section 6 will provide a month following which work can commence as long as everything is to be able in terms of the act. Once more there are many ramifications associated with adjoining owner dissent, non reaction to notices or sheer bloody mindedness but I'll leave these for a later date, or for your party wall surveyor to help you upon. Or you might find that the adjoining owner just consents to the work in which case you can begin earlier by mutual consent!
Even though the adjoining owner does consent i quickly would advise a schedule of condition prepare yourself on the wall to make sure that you have a record of any cracks or defects before you begin work. You'd be amazed at just how many times a neighbour spots cracks after work has been completed, that were actually there before!
If however the adjoining owner dissents to the task and appoints their own surveyor, as they are entitled to do beneath the act, then you will also require a party wall award to document agreed standards and incorporate the schedule of condition. Under these situations, unless you really know what you are doing you need to get help. It's worth noting however, that when your neighbour does appoint a surveyor then as building owner it's likely you'll be responsible for their fees.
The Act is really a fully established act of parliament and therefore is law. Ignoring the Act is common place (often through insufficient awareness) but technically the perpetrator is then breaking regulations. I could get into detail regarding the implications of deliberately failing woefully to serve notice but if you're a building owner scanning this article you then are clearly already alert to the act and concerned that the process is correctly followed. When you are on the other side, where a neighbour has not served notice on you, there is recourse but you should seek professional advice. It is also worth noting that ignorance is not any defence with regards to the law.

It is often believed that the act is merely designed as a money spinner for professional consultants but this couldn't be further from the truth. Yes there is a business built around the act and professionals do charge because of their services, but there is enough competition to ensure that fees remain reasonable. It is actually an enabling act that means that the positions of both parties are protected and more importantly, ensures that neighbours cannot stop development or repair without sufficient reason. In this regard the act can often save fees where there is once a prospect of litigation and dispute.
Despite this, it is common for projects to be undertaken satisfactorily without serving notice but this is the risky proposition as shown by the case of Louis v Sadiq 1996. The case revolved around a finish of terrace house in London and shows the implications of the act on standard houses and thus general home owners, not just large scale developments. Mr Sadiq (building owner) completed building work without serving notice beneath the act. This work subsequently caused harm to the neighbouring property and he was forced to make good this damage by the court beneath the terms of the act. That is standard procedure and also if he had served the right notices he then would still have already been responsible for this cost, but more importantly with what we have been discussing, the courts awarded additional damages to Mr and Mrs Louis (adjoining owner) since it felt that Mr Sadiq's failure to see the act negated any benefits of defence that he might gain from the terms of the act and for that reason special damages were allowed. In this instance the Louis's were awarded compensation to cover additional costs incurred through a failure to sell their residence due to the defects plus they were even awarded charges for rising construction costs regarding the their new house abroad. Had Mr Sadiq followed the right procedures and served the appropriate notices then these substantial additional costs wouldn't normally have been incurred. He'd only have been liable for the cost of putting right the damage, not the additional costs. This example is by no means common place but does go to shown the potential implications of not following a correct procedures. What seems like a sensible saving on surveyor's fees could turn into a substantial cost for damages. You have been warned!
This brief article is aimed at giving a layman's view of the act for information purposes instead of a complete technical assessment. You need to seek professional advice if carrying out any work to, or near neighbouring land or property. It should also be noted that the act doesn't have any bearing on any other legislation, like the requirement for planning permission or building regulation approval etc which are completely separate entities.