Usually you would soak the hide roof with water first. Makes it pretty damn fireproof. Oil and other liquids wouldn’t be a huge problem unless they’re literally right below your walls (and your moat would be several feet wide at least). Arrows would still be an issue at closer range, but that’s why you cover this thing with your own volleys and siege engines.
That looks perfect to turn into a crematorium with a few flaming arrows or boiling oil
Usually you would soak the hide roof with water first. Makes it pretty damn fireproof. Oil and other liquids wouldn’t be a huge problem unless they’re literally right below your walls (and your moat would be several feet wide at least). Arrows would still be an issue at closer range, but that’s why you cover this thing with your own volleys and siege engines.