Basement construction is increasing in popularity due to limited space and soaring property prices. If you wish to add space and value to your property, basement construction may be for you. Due to the nature of the works, such projects can also impact neighbouring properties, making obtaining a Party Wall Award essential. In this blog, we will be discussing the role of the party wall surveyor during basement construction, the necessary steps involved and how they work along with other practices such as structural engineers. 

Party Wall Act

First of all, what is the Party Wall Act 1996? The Party Wall Act 1996 is a piece of legislation that governs the construction of work close to neighbouring properties. The act aims to safeguard both property owners during the construction process. The Party Wall Surveyor essentially acts as a mediator between the two parties, provides expert advice on the requirements of the act and assesses the properties before, during and after the building works commence.  


The first step is determining whether the work is notifiable under the Party Wall Act 1996. These works include the following. 

  • If you work on an existing wall or floor structure that is shared with another property such as; a loft conversion, supporting a beam on a Party Wall, removing walls in a flat or excavating for a basement.
  • If you are building on, or at the boundary with another property.
  • If you are excavating near neighbouring buildings to a lower depth than their foundation.

The notice informs the adjoining owner of the proposed works and their impact on their property. The Party Wall Surveyor helps prepare and serve these notices, ensuring they are accurate and comprehensive. In this blog, we will be looking into aspects concerning basement conversions. Once the notice has been served, the adjoining owner will then have the following options. 

  • Provide written consent with conditions within 14 days
  • Serve a counter-notice
  • Provide written consent after 14 days from the day of the notice
  • Refuse consent, which will start a dispute resolution
  • If they decide to do nothing, after 14 days this will be recognised as a dispute. 

Once the response from the adjoining owner is received, the surveyor(s) will start drafting the Party Wall Award. This legally binding document outlines the rights of all parties involved and sets out the work that proceeds. However, before the works continue you must collect the relevant Information.

  • You must have all the calculations of the works and the engineering drawings (this is not always available whilst the Party Wall matters are ongoing).
  • You need to obtain architectural drawings.
  • You will need the temporary works information, this will be the most important piece of documentation because it looks at how the basement will be dug out. (The neighbours’ properties are most at risk when the basement will be dug out as it can affect the potential neighbours’ extension Party Wall).
  • The soil conditions will need to be checked, which include borehole information and trial hole information.

A Schedule of Condition should also be included in the Party Wall Award. This report will document the current condition of the adjoining owner's properties, particularly in the areas most likely to be affected by the basement construction. The surveyor prepares this report to ensure that damages can be easily identified and that claims of damages are valid. 

Structural Engineers

The structural engineer's role is to design the structural elements of the basement and ensure that the proposed works meet building regulations. The Party Wall Surveyor will review the proposed designs and the impact on the adjoining owner.

Due to the nature of the works and the high level of risk involved in basement excavation, it is generally accepted that a surveyor acting for an adjoining owner can seek advice from an independent structural engineer at the expense of the building owner. Generally, where there are several different adjoining owners surveyors, it is usually agreed to use the same structural engineer in order to prevent the process from becoming costly and time-consuming.  The advising structural engineer is there to review the drawings and calculations and ensure that all reasonable steps have been taken to reduce the risk of damage. 

Interim Visits

Party Wall Surveyors are not there to police the works however it is accepted that they are entitled to access the building owner's property to check the progress of the works. Typically, the adjoining owner will make one interim visit, generally at the halfway point of the works to ensure that works are proceeding in line with the Party Wall Award.  If issues arise during the works further visits may be justified. 

Completion and Final Assessment

Once the works are complete, the adjoining owner's surveyor will return and do a checkoff, essentially comparing images taken after the works to those in the schedule of condition.  This will usually take place a few months after the works have been completed as this gives the disturbed ground time to settle. The final assessment ensures that all parties are aware of the condition of the adjoining owner's property post-construction, helping address any potential dispute. 

Security of Expenses

Under section 12 of the Party Wall Act 1996, the adjoining owner has the right to request a sum of money in the event that the works are abandoned, compromising the structural integrity of their property. The amount held should equate to the amount to restore if the works stopped at the worst possible point. If a dispute arises, it is to be resolved by the appointed surveyors. The security is to be held in an account out of reach of the owners, and when the work is complete it is to be returned to the building owner.


As mentioned previously, there is a high risk of damage caused to the adjoining owner's property as a result of the basement excavation. Even when following all necessary procedures, sometimes damage is inevitable. Under section 11(8) of the Party Wall Act 1996, the building owner has the duty to make good on any damages caused by the work. If the building owner and the adjoining owners fall into a dispute over the cost of the damages, the appointed surveyors will inspect the damage and reach a financial settlement that both parties agree on.

Planning Permission and Building regulations 

Besides the Party Wall Act, your proposed basement construction must also comply with planning permission and building regulations. If you are excavating, you will almost certainly need planning permission. It is advised to contact your local planning authority at an early stage of your project. You will also need building regulations to ensure that your purposed basement conversion meets health and safety standards.


Basement construction can have long-term implications for both the building owner and neighbouring properties. It is essential for the party wall surveyor to consider these aspects during the entire process. They ensure that any necessary agreements regarding future maintenance and potential issues are included in the Party Wall Award. This forward-thinking approach helps prevent potential conflicts and ensures that the construction benefits all parties involved in the long run.

Basement construction offers a valuable solution for maximizing living space and property value. However, the involvement of a qualified party wall surveyor is crucial to navigating the legal complexities and potential impacts on neighbouring properties. By understanding and adhering to the Party Wall Act, working closely with structural engineers and maintaining open communication, the surveyor helps facilitate a smooth construction process. The collaboration between professionals ensures that basement construction is not only successful, but also protects the rights of all parties involved.

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