Advise please, our foundation is extending to neighbours property

[biscuitsndtea]

Our neighbours are building two-storey side extension converting their garage space.

We had our garage attached to each other. Our garage was converted to two storey extension 20 years ago. We bought the property just a year back. There was no completion certificate for the extension.

As our neighbours are converting their garage to a two storey extension which is adjacent to our extension ( garage to two storey extension done 20 years back) We have got our party wall agreement in place.

The problem is that while their builders started digging, they found that foundation of our extension has been projected to their side.

Not sure, how our foundation was projected when their garage was already there? Is there a chance that foundation for both the garage was built/put together when it was built first(1930s semi detached) ?
What should we do now ?
If they cut off our foundation, will it cause any problem like subsidence to our property ? This is our main concern

This is our first home. So we are very much worried now.

Any inputs would be helpful.

If there is a Party Wall Award in place, then I think you or they can go back to the Surveyor who made the award and get him to work with the builders to come up with a practical solution.

I had a vaguely similar situation when adding an extension (semi-detached bungalow). The neighbours were concerned about it causing their extension to collapse. The PW Surveyor approved a slightly different way of laying the foundations for my extension, which cost about £1K extra. Building Control also came and were happy with the approach.

But don't panic - there is always a solution, and the PW Surveyor is there to ensure no damage on either side.

Sounds weird.

Unlikely to me that when the builders did your side they hollowed out beneath the neighbours garage to put your extension foundations there - so it was probably there since the garages were built.

Anyway, I would have thought it is just a matter of incorporating what's there into their new foundation, but needs looking at by a professional.

Check your house insurance, there's usually a helpline you can phone for advice.

@biscuitsndtea , first of all I wouldn't worry too much. Just because they are cutting into the foundation doesn't mean there is a risk to your property. It sounds like something that happens frequently (similar to cutting into walls), and builders and surveyors will be used to encountering it, along with Building Control, who have presumably signed off on your neighbours' plans.

On the PW agreement: assuming more than 14 days has passed since the agreement was signed, the agreement is binding and cannot be withdrawn. The agreement should state that any damage will be rectified at your neighbours' expense, which may offer some reassurance. As I understand it there is also a dispute resolution procedure for any issues that arise during the works. I found this on a legal website, quoted from RICS:

"RICS Even if Notice has been served and written consent obtained, it is still open to an Adjoining Owner to dispute ‘any matter connected with the work. On these occasions there is a course of action in the Act which can be invoked if the parties cannot agree. Section 10 stipulates that where an Adjoining Owner does not consent in writing to works notified by the Building Owner, both parties must either agree on the appointment a single surveyor to act for both of them (known as the Agreed Surveyor) or each appoint their own surveyors, to determine the time and manner in which those works are carried out. It also establishes a procedure to resolve any disputes between neighbouring owners that might arise in relation to those works, including damage occasioned to an Adjoining Owner’s property caused by them.
Consent, once given cannot be withdrawn, but if, for example, you carry out work different to that stated on the notice and/or otherwise agreed (S.7(5)) or undertake it in such a way as to cause unnecessary inconvenience (S.7(1)) or cause damage to the Adjoining Owner’s property (S.7(2)) or contravene any other provision of the Act, the Adjoining Owner can invoke the Section 10 dispute resolution procedure, even after the work has been completed."

I doubt this will prove necessary, however.

@ClematisBlue49 thanks for the detailed response x

@WetsuitRevolutionary thanks for the suggestion , what should we ask the insurance people ?

We reached out to the party wall surveyor. He was not helpful, he is saying that they have all rights to cut our foundation since its their boundary. It was built 20 years ago, we have no idea why it was built in that way.

• Can we appoint any structural engineer from our side to validate their plan
• If the structural engineer or any surveyor from our side say that it will cause damage to our foundation, can we challenge them.
• How can we challenge their proposed plan if needed ( in case if it will damage our house) ?

We dont have problem with their extension. Our only worry is about damage to our foundation.

They will only be filling in the bit of your foundation thats cut off with concrete anyway , so if anything your foundations will be stronger as they are technically pinning them up ( and probably deeper with modern regs ) .

If a building control officer approves the plan, can we consider that it wont affect our property.

While approving the plan , will the building control officer consider the impact to their building or will they consider impact to our building as well ?

Building Control sign off drawings where the proposed design, materials and methodology are in line with building regulations. It's the Party Wall Surveyor who is responsible for ensuring no damage to the neighbouring property, whether they are appointed to represent just you, or the same Surveyor is acting for both sides. My PW Surveyor said that, effectively, he represents the wall (!) and that would extend to the foundations below.

The PW Surveyor may suggest a different approach if something unforeseen comes up, which can then be agreed with Building Control if it isn't as shown in the drawings. If the PW Surveyor in your case knew that the foundation was going to be cut into, but was happy to sign off on the works, then that suggests to me that they had no concerns about it impacting your property. If it was only discovered after the award was in place, then you need to raise it again with them in the first instance as the Award may need to be amended to take account of it, and if there is any significant variation (unlikely), your neighbours or their builders would need to ensure Building Control are still happy.

If the Surveyor won't respond to your concerns at all, then you should let your neighbours know this. The dispute process in my previous post would be a last resort, in which case you might need to get advice from another PW Surveyor.