
So here are a couple ideas for more types of roofing.
Clay Roofing Tiles
We could craft clay tiles and fire them similarly to bricks, allowing for a variety of new roofing colors with the existing range of clay.

Also, our hearthlings easily have the technology in place to produce this kind of structure:
Flat tiles: https://youtu.be/P73REgj-3UE?t=3m20s
Barrel Tiles: https://youtu.be/q9AoGc-OTCk?t=6m37s
Sheet metal roofs
While this is not really appropriate for the time-frame Haven is set in, it would be another (albeit small) sink for metal in the late game and let us have more variable roofing materials.

Slate roofing could also be an idea, though I'm not sure how to go about separating the roofing stone from stone elsewhere in the construction.