The thatch is actually a lightweight aluminum, the profile is similar to weadeatrr line. All of the pieces are attached to a common bar and screwed down to the roof surface. Where the thatch is not up close and personal with the guests, it is a plaster ceiling with a profile and paint to make it look like thatch. Also the thickness if the thatck at the edges of the roof is an illusion, there are large end pieces that go on the edge of the roof over the fascia to make the thatch loom 8-10” thick.
You might ask how I know this, it is because I got up close to the thatched roof in the top of the outside spiral staircase at animal kingdom lidge on 6th floor. A single piece of thatch was broke and laying on ground and you could see where it broke that it was aluminum inside.