Applying points to a surface to create a ramp

Hi everyone,

I would like to know how to add points onto a curved surface, what I am trying to achieve from this is to create a ramp the follows the curvature of my building which visitors can walk up and onto the roof.

Basically I would like to add a start point, an end point and then dynamically create all points in-between using some sort of grasshopper script(?). From these points I would then like to build out from the wall the create the surface of the ramp.

Below is a crude version of this where I manually manipulated points on the surface, created a curve from these points and then extruded it outwards, though as you can see it is very turbulent, and not the smooth rising surface I would like

Many thanks

Lee