If it is just for aesthetics you can use the corrugated cardboard trick. Drop down 1 meter and put wood flooring on, alternate 26 degree thatch roofing to make the corrugations, and put wood flooring on top of that. Looks smooth from the top and the bottom and keeps the weather out. The top floor tiles weather down to 50% health but no farther. You can cut a smoke hole through and put a chimney cap over that to let smoke out if the inner roof is too close to the fire to allow dissipation.