Build rear extension to adjoining neighbours extension

[gomo]

Hi,

I am hoping the very knowledgeable members of this forum could clarify the following;

My friend is proposing to build a single story rear extension to extend the existing kitchen and incorporate the side return of his mid Victorian terrace.

Both the adjoining neighbours already have rear extensions to their properties.

The question is can the builder use the existing exposed walls of the neighbours extensions which sit on the boundary and therefore only dig foundations for the rear wall of the new extension only please?

Thanks

[pilman]

Only if there is a prior agreement to link that back wall into the existing brickwork that belongs to each of the neighbours.

You may be able to persuade the neighbours to allow that to happen since their external wall will become an internal wall kept free of weather and will not need regular repairs in the future. It will still be the neighbour's property, so be prepared to offer money to secure permission, because you will still need to attach insulation or at least plaster board to their external wall that will become the inside of your extension.

There needs to be a steel slotted strip screwed vertically on each of those walls, then steel wall ties can be located where each course of bricks is tied to those walls.For a cavity wall that will need two vertical strips each side.

Look at "Wall Starter System" on Google to see how these are used, but everything will depend on neighbour's good will.

[gomo]

Thanks for your reply pilman.