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PROPERTY CLINIC: I want to extend my semi-detached property into the roof or basement – what do I need to know about the Party Wall Act?

I live in a semi-detached property and would like to extend it either upwards into the roof space or down to create a basement.

I’ve heard the Party Wall Act comes into play for this type of work but I have no idea what it is or what I need to comply with.

Homeowners need to ensure they comply with the Party Wall Act if they are thinking about extending into the roof or basement of their property

MailOnline’s property expert Myra Butterworth replies: You may be tempted to go ahead with the work without taking into account of the Party Wall Act, but do so at your peril as it could end up costing you financially.

However, the whole process need not be timely nor costly, especially if you are as open as possible from the outset with your neighbours about the work you are looking to undertake.

James Audsley, partner at surveyors Malcolm Hollis, said: Many people do not understand what the Party Wall Act is about, but it could cost you a lot of money if you don’t follow it.

Despite appearing to be extremely technical and complex, the principal behind the act is very simple and it is there to preempt any conflict that might arise when one land owner is undertaking building work next to someone else’s land.

Following the Party Wall Act should protect both land owners from any issues that arise. Not following it could leave the person undertaking the work open to neighbour disputes, where legal fees became the biggest matter at hand.

The Party Wall Act 1996 was implemented in July 1997 and applies throughout England and Wales. Before then other London focussed legislation existed such as the London Building Act 1939 and regulated party wall matters.

A party structure is simply a wall or floor that separates two different owners and is jointly owned or shared. There are two different types and yours is likely to fall into the following category: The party structure forms part of a building and stands on lands of different owners, such as walls separating terrace or semi-detached properties or a party fence that forms the boundary between two gardens.

The objective of the Party Wall Act is to promote not hinder development. You have the right to undertake certain works but need to follow the requirements of the Act. Equally it recognises that neighbours may be impacted by certain works, and so provides a framework for notifying neighbours and resolving disputes if there are any. Therefore it offers protection to both the building owner and neighbours.

However, the Act is limited. You do not have to notify your neighbours about all development works, for example, putting up shelving by drilling into the party wall is highly unlikely to cause major damage to a neighbour’s property and therefore would not require you to provide your neighbours with a notice for this work.

In this circumstance, common notifiable works for loft extensions include increasing the height of a party wall, inserting steel beams into the party wall and cutting into the party wall, or an external wall for inserting flashings. For basement extensions it might be works such as raising a party wall downwards, underpinning and excavation works that requires you to give notice to your neighbour.

The rise of basement extensions

Basement schemes are on the increase, particularly in London where the ability to extend out and up is limited. However, these schemes are complex and require a good design team as well as a competent contractor to limit the risk of damaging a neighbour’s property.

Neighbours of such schemes are increasingly demanding security deposits, sometimes thousands of pounds, in case the building work goes wrong or works stop unexpectedly. This can increase the potential for projects to be delayed, as well as tempers to fray, as neighbours or their surveyors disagree over the necessity of such large amounts of money as security.

What to do before the Act is brought into play?

First, you need to check with your local authority if planning permission is needed for the work you wish to carry out.

You should always get your proposed works reviewed by a reputable party wall surveyor to consider what works, if any, are notifiable. The Pyramus and Thisbe Club ( is a good place to start your search for a member who is experienced in dealing with the Act.

Giving your neighbours notice

Once you know what works are notifiable, notices will need to be given to qualifying neighbouring owners.

It is the duty of the building owner to serve the appropriate notices in the correct manner as required by the Act. The party wall surveyor can assist with the preparation of these and you can give your surveyor written authority to sign and serve the notices on your behalf, if you wish.

Notices should not cost too much to prepare and issue, typically a few hundred pounds, and they need to be served in good time before you propose to undertake the works. There are minimum timescales required before the works begin – up to two months prior. That can be waived with the agreement of your neighbour but it can take longer if your neighbour disagrees with the notice and you need to appoint a surveyor to agree a Party Wall Award.

It is worth noting that notices only have a shelf life of 12 months.

Once the notice has been served, your neighbour has three options. They can consent to the works, remain silent or dissent. It is a good idea to engage with your neighbours before the notice is served, take time to explain the works and maximise the ability to get their consent.

Consenting neighbours

Consent means no Party Wall Award is needed and surveyors do not need to be appointed to agree an Award authorising the notifiable works and incur additional fees for undertaking that role.

Silent neighbours

If the neighbour is silent, they are deemed to disagree and an award is needed. Before that, another notice is served giving the neighbour 10 days to appoint a surveyor. If they don’t respond, a surveyor can be appointed to act on their behalf.

Neighbour gives dissent

If the neighbour gives an actual dissent then either an agreed surveyor or two surveyors for each side must agree an award. The surveyors have a statutory function to perform and must act impartially.

They must undertake certain formalities, usually agreeing a schedule of condition and review the time, manner and extent of the works, to check they will not cause the neighbour unnecessary inconvenience. If satisfied, the surveyors conclude an award. That does cost money in terms of surveyor fees – however, you are getting permission for works, which hopefully is adding value to your property.

Once the dispute is resolved the surveyor’s involvement is complete. They are only involved again if there is a claim for damage or there are others matters which the developer and neighbour cannot resolve themselves.

Other aspects surveyors may need to consider

There are other more complex aspects that surveyors need to consider sometimes – for example, a development may make use of a party wall and a contribution for the use of that wall in financial terms is needed.

A development may require temporary access over a neighbour’s land to facilitate the notifiable works. The Party Wall Act gives access rights in certain circumstances, which would not be available under common law.

In conclusion, the whole process need not be time consuming nor costly. The earlier you can engage with your neighbours the better. Be open with them about the work you wish to undertake and be as understanding with them as you would wish them to be of you.