Game mode: Singleplayer
So from the last patch notes announment it says that:
However I cannot attach at it’s lower point no matter how much I’ve tried, the only exception being with T1 - Inverted Thatch Wegde Sloped Roof. All the other Tier roofs or DLC roofs will refuse to do so, instead forcing the attachment on the upper part of the roof. Also made ceiling wedges on top of pillars that could give stability for this piece to attach in the right place (just to make sure it wasn’t being stubborn about the angle like some other pieces) but as soon as I break the ceiling, the inverted roof will collapse. Though maybe I just had to put at a certain angle, but the Thatch Wedge Sloped Roof attaches quite easily.
Here is a picture of all 11 possibilities of roofs (sorry for the bad quality)