fitting patio doors upvc below damp?

[bullwhip]

Hi there hope someone can help.

I'm goin to purchase a set of bi-folding doors for an extension, ideally i want the minimum step from internal finished floor level to external finished floor level.
The manufacturers of the door have said that the step is 150mm in the door unit (seems prety large) and have sent me the following pic to illustrate.
http://screencast.com/t/bGQhGXLbZxp

My questions are: how do i acheive a seemless transition from interior to exterior without damp problems. Can a course of bricks be removed to sit the door unit below DPC? Any other suggestions?

All responses welcome!
Regards

 

[crank39]

I would email them back and ask why it has to have that frame extender/add-on in between the frame and cill, thats probably 50mm on its own