Cavity wall for New Extension above carport and Garage (Ed.)

[ExSparky_Phill]

I'm looking to build above my carport and garage and have a few queries if people could advise please. The garage is single skin and initially my plan was to extend the footings width and build a new outerskin which would continue for the 1st floor extension. BC was OK with this, just couldn't get an answer from the SE. Because of this, I've decided to rebuild the garage completely. Where I'm building above the carport, the external gable wall of the house becomes the internal wall for the extension and the back wall and roof of the extension are to be inline with the existing house wall/roof. My queries are:
1) When the lintel/beam goes in above the carport, does this sit on just the existing outer wall or does it sit on both the outer and inner walls of the house?
2) As the wall is built up, is a cavity created in the corner of the extension on the existing wall, i.e. a 100mm section cut out of the existing wall to allow the cavity to continue?
3) at the opposite end of the lintel above the carport, again does the lintel sit on both the inner and outer walls?

Thanks

Phill

 

[^woody^]

The new lintel sits on the existing outer leaf. However, the existing outer leaf is cut vertically to create a new inner wall section.

 

[ExSparky_Phill]

Hi Woody,
Thanks for the reply, for some reason, I had it in my head that the lintel had to sit on the internal wall of the existing house wall.

Phill