Verge undercloak queries - help needed!

[RVS6]

Hi
I am building a small lean to extension, brick/block cavity wall and concrete tiled roof. Planning to have a traditional mortar bedded verge using fibre cement undercloak. I have two queries:
1. Should the undercloak be bedded on mortar (appreciating it fits under the roof batten).
2. Should the outer brickwork be set circa 10mm lower than inner blockwork height (and therefore rafter top) to allow for the mortar bedding of the undercloak? Seems to me that this would be the only way to get the required downward slope on the undercloak away from the wall.

Any advice would be appreciated.

Thanks

 

[^woody^]

Yes and no.

 

[RVS6]

Thanks Woody, but not understanding. If the undercloak s bedded on mortar on the outer brickwork would that not push it higher than the underside of batten that it is supposed to sit under, or it would force the undercloak to slope towards the wall?

 

[^woody^]

It's a very thin bed. The undercloak is put on level, but the battens and end tile are meant to be kicked up a little so that rain does not drip off the verge but runs down the roof.

 

[RVS6]

Thanks Woody. So you are saying that the top of the inner and outer skin are laid to the same level as the top of the end rafter?

 

[^woody^]

Yes

 

[RVS6]

Woody, I am having double pantile concrete interlocking tiles, so rainwater will naturally be shed off the tile down the side of the verge especially at the RHS (kicking up of the batten ends wouldn't make any difference). So in this instance I understood the undercloak needed to be installed at a slight angle away from the wall to ensure water doesn't flow back against the wall surface and soak it. I did a little more on-line digging and found the attachment included here (not profiled tiles). So the only way I can see to do this is to have the brickwork set a few millimetres lower that the bottom of the batten/top of rafter and then bed the undercloak in a thin bed of mortar wedged under the battens. It seems to make sense, or am I missing something here?

Sorry to labour the point, but it has been doing my head in.