Not removing outer leaf for 2 storey extension ?

[SimonH2]

I'm looking at a house which has had a 2 storey (full height) extension built on the back. It's something I've noticed before, but why not remove the original outer leaf ? In this case, the extra 8 inch would have made a noticeable difference, and I assume that leaving the outer leaf in place creates a huge cold bridge. There's nothing being supported by it.
So is it just a case of "can't be a**ed", or are there ever technical reasons (other than it's supporting something above) for not removing the outer leaf ?

 

[John D v2.0]

I think the cost would outweigh any advantage of space or thermal bridging. Pure economics.

 

[tony1851]

If you are building a side extension, where width may be limited, it can sometimes be advantageous to remove the original outer skin - at least upstairs - to gain an extra 6".
Sure, there is the cost of another skip, and the re-plastering (though the original outer wall would have to be plastered) but it might make all the difference in space.

 

[SimonH2]

In this case, I can't help thinking that the saving on lintels and their fitting would have outstripped the cost of knocking down a few bricks.

 

[noseall]

knocking down a few bricks.

Do those bricks magically hop their way into a free skip too?

 

[^woody^]

What will then stabilise the 100mm inner wall which is holding up the roof and floor?

 

[tomfe]

Building regs require a minimum thickness for a single skin wall of 140mm up to 2.4m.
If your ceilings are more then this then you need thicker walls unless you have a se input.
You won't get this with a half brick wall so you'd have to get a se to do a calc on it.

 

[tony1851]

A 102 brick wall 2.4m high supporting the roof would be fine.
(It would not be adviseable to take the whole wall down in the ground floor as well, only for the upper floor).

 

[John D v2.0]

In our case we had a 2 inch thick internal wall supporting part of the roof, the SE wasn't happy with that and specified four steel channels, two on each floor to give the wall some stability. So as with all things it depends how much money you have.