Don't use a brick foundation, it cost money and makes the building look more constructed. Use 1 material (Mud, Stones) for the walls, and have small holes here and there. Make the windows oddly shaped like they were dug out of the wall instead of carved. The rafters are a good idea, but have them go strait across rather then hugging the roof. Rafters that hug the roof would involve carving the wood to perfectly fit, which is time consuming and expensive, from what it looks like, your going for a run-down hut. Also think about having an uneven dirt floor inside, rag beds, etc.