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Submit plansI have an end-of-terrace house that's next to a railway line. There is considerable subsidence to the shared wall - which is further away from the line. I want to extend the property to the rear and side closer to the railway track - would it be better to knock down and rebuild with a new set of foundations, or will the extension be enough to support the rest of the building? And what measures can I put in place to ensure subsidence does not occur again?
Hello,
When we come across issues like cracks due to potential subsidence we would recommend that a structural engineer gets on board to investigate and monitor the situation. They will then be able to understand what could be the cause. Given that you are next to a railway line, I would expect that if this were the cause of subsidence that you would also see issues with the wall closest to the railway? However, you infer that it is the wall furthest away, so this could be a localised issue relating to your party wall with your neighbour. In which case they will also see and have issues in their house and you should consider talking to them about resolving this issue. I’d expect that to deal with this will be a localised issue and perhaps you will not need to underpin the entire existing structure.
On exposing the part wall foundation you should also have a trial pit dug for where you intend to extend your house to understand the ground condition in this area. This will then determine the appropriate foundation you will need for the extension. It is likely that the extension foundation will be separate to the main house and not be able to support the existing house. Your structural engineer will be able to guide you on this once they understand the ground conditions.
Best,
Opinder (architect & Build It Expert)