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Using a neighbour's existing extension wall as part of my new extension wall.

I am buying a mid terraced house which I intend to extend. The neighbours on both sides already have extensions - one is about 450mm on their side of the boundary so presumably not relevant, but the other has been built right up to the boundary. Am I allowed to use the outside of their wall as part of my new extension, and if so, do I still need a cavity and internal wall on my side of the boundary?
Also, I intend my extension to project 1 metre further out than the one on the boundary so how would I be able to do this if I am able to use their wall as part of mine?
A further problem I noticed is that the neighbour's flat roof and fascia overhangs the boundary and their 'flat' roof is also at an unusually steep angle. My roof is likely to be flatter and at a higher level - should I remove their fascia board and overhang, and seal the edge of their roof to mine somehow?
Any help would be appreciated - thanks!

2 Answers

Best Answer

Your structure must be independent of the neighbours.

If they were ever to decide that they wanted to remove their extension or change it to something else then your structure would be compromised.

As to what has been built already it sounds like the neighbours builders may have used an elastic tape !!!

It's too late to rectify the problem now but as you're in the process of buying the property a reduction in the price is your best option.


Answered 6th Feb 2014

Rule of thumb is 1 meter from the boundary of adjoining properties/land or right up to it. Any neighbouring extensions should not encroach onto other people's land regardless of height however, as intimated, this could easily remedied when tied into the new build. Any and all specifications toward cavities and insulation for the thermal calculations will be detailed by your architect. Hope some of this helps? David (Trinity Roofing)


Answered 16th Dec 2013

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