I am unable to answer your question about the roof but I wanted to add some possible help. If you're modeling the beautiful Chama Sand House, a friend that visited summer of 2018 mentioned there was a modification to the front door due to an incident with a piece of equipment pre-season. So make sure you use photos that are pre-2018 for modeling the overall structure if trying to stay historically accurate. Upon studying photos from this past season it doesn't stand out badly but to the rivet counting modeler it will stand out on a model! Now for the roof, an uneducated guess but I would suppose the old roof was tin at that time.

-Maury