The thatch roof was sodden from rains. In the V between the steading proper, and the kitchen extension, water collected. Kahru would be able to shape it into a form that could climb up the roof and jump into the smoke-hole. It might not fully put the fire out, but it would make it easier to avoid, and be an effective momentary distraction.
There were six people on the roof. The colonel's updrafts could carry five down. Either Donnell could remain on the roof until the danger was past, or someone could find their own way down. The plan was sound, though the danger was real.
Waythe urged Kahru to get on with it, eagre to see how many giants she could slay.