Patio flush with Bifolds

[visionset]

Okay not quite flush, just higher than the DPC. So how to mitigate the obvious issues? The photo shows the intended small patio area within the red. My initial idea is to build a small wall along the green line as a retainer for the patio to the right, and leave a trench area to the right to avoid bridging the dpc and then put in a suspended floor over that trench, this could essentially be a drain grid or just decking. the garden is virtually level so a fall away from house is easy. And the soil is very sandy and free draining with foundations directly on sandstone. I wasn't going to provide anything other than straight into the ground below the trench. The eaves here are 600mm on single storey lean to here, but does face west so gets lashed at our low rainfall east mids location. Does this sound okay? Any better solution, and source of suitable linear drain grid? They seem extortionate. Thanking you!

 

[Notch7]

Slot drain or threshold drain

http://www.drainage-channel.co.uk/c...xFAUTjstUkIePQSvOH47udvZPc_Y6pzBoC8uYQAvD_BwE

 

[visionset]

Okay, I've looked at other forum posts too. It seems quite straightforward. With a plastic drain this fulfils the membrane you would otherwise put against the wall as you bridge the DPC. However I think as you bed the drain unit into its concrete footing it would be better to plaster the side of the channel with mastic before pushing it against the wall and bridging the DPC. That would seem to be the best belt and braces. Then on other side of unit on same footings build a wall or curb units to height of patio and have patio fall away from drain to garden. Drain is then purely for flash flood and runoff from bifold glazing. Have I got that right? Any issues / misunderstandings?