I dont see anything in my brochure, other than the roof is crowned from 1 1/2" to 3 1/2". I can assure you the roof on mine is as solid as a rock.
The storage doors are 1" thick so the walls have to be atleast 1 1/2" to 2" thick.
You might have to get a more accurate answer from Northwood since I dont see any specifics on the floor and walls in their brochure.