posted 9 years ago
Have you ever had an earthquake in your area? If so, I would not trust cob walls alone to support the roof. 60cm at the base is good, but 25cm at the top is fairly thin.
Are you planning to have a ridge supported on posts or on the cross walls I see? If a ridge is supported by other means than the outer walls, you will have short spans and the walls can probably take the load.
Do you ever have hurricanes or very strong winds? in that case, I would want a post structure to hold the roof edges down. I wouldn't trust just the weight of 10-20cm of cob to hang onto the roof well enough.