Create Insulation Layers Under Stair


I have to make insulation layers under a staircase, which should follow the shape of the bottom of the stair. These layers have different thickness (and materials, although I don’t think this is very important right now)

I tried many ways to make it work, tried to do it manually in rhino and also in grasshopper, the “best” result I could get is the attached gh file (the rhino file has the part of the house the stair is in and some referenced geometries I am using in the gh script, there are some hidden geometries that you can show if you want more information of the surroundings of the stair, but I think they make it more difficult to understand the stair)
In this case the thickness of the layers are not constant throughout the shape, their positions also get “messy”, some holes appear in some places, and so on.:

I tried to build it as surfaces and meshes and offset them, but the results get super weird…!

The loft is not nice as well, it “eats” on the steps of the stair:

Can you please help me?

Thanks for your kindness!

Stair.3dm (11.2 MB) (25.1 KB)