Sod rooves traditionally had birch bark layers put on first, then the sod layered on top. I will use decking and probably vinyl flooring material to fully waterproof the roof and make steps in it with boards underneath to create pockets that hold water in reserve.
I know the creosote fumes will get bad inside so am planning to whitewash the whole inside unless someone has a better idea. A friend recommended Gunite but that's beyond my means. Maybe plaster, we'll see.
I don't know about alien influence or them leaving technology with us which can cut and move thousand ton blocks of impossibly hard stone hundreds of miles or if it was advanced human civilizations lost to time and destroyed by massive natural cataclysms (probably several cycles of this), but one thing is for certain: the worldwide monolithic block constructions weren't made with ropes, logs, copper saws, and bronze chisels. It's just mot possible. If you don't believe me, get a rough chunk of ordinary pink granite (not as hard as andesite or basalt) and some brass or copper rod and a sack of blasting sand and tell me how long it takes you to make a polished flat spot on it. While you're at it, jack up a 200,000 pound block of rock, stuff a bunch of wooden logs under it, and tell me how well it rolls after the logs are crushed to dust. Look at photos of the quarries at Aswan, Peru, and India to name a few and tell me what device was used to slice out huge chunks of basalt like a hot wire through foam. It wasn't a string wetted and coated with sand. The feats the known civilizations are credited with performing with primitive tools and manual labor are ludicrous. Another observation is that when we look at these things and imagine how impossibly time consuming and difficult it must have been to do them that way....we're wrong. It was actually pretty easy using whatever technology was available. It HAD to be easy or it never would have been done. So, alien visitors or not, we've all been lied to our whole lives about how all this really ancient massive stonework was really done. The Egyptians didn't construct the pyramids at Giza, the Inca didn't build Machu Pichu et cetera (they've said as much from the earliest Spanish accounts, they rebuilt ruins crudely and added to them, the difference in workmanship is blindingly obvious), and the Romans didn't build the foundation of the Baalbek temple. These civilizations inherited the structures in a damaged or incomplete state and built on top of and/or expanded them. Whodunnit originally? I don't know but it has driven me to distraction most of my life, ever since I was a kid and first saw a photograph of the walls at Sacsayhuaman and wondered wtf that was ever done by a civilization that barely had gold and copper for metal and no diamond tooling.
