I'm surprised no one jumped on this. I am far from an expert but i built a PSP house this year and have visited Mikes buildings. I highly recommend it for a first house on the cheap.
Green posts and beams were used in my home some a few months old but most were much much greener. That could cause some mold and or the shrinkage of it drying could make it less than sound i have heard. To try to mitigate the mold i put a
wood stove in once the walls were up and ran it hot and often. it helped a great deal with drying all of it soon the logs showed signs of being very dry. I was worried this might cause a structural issue as they shrunk but with the way PSP is designed it all seams to lock together tight . its a very sturdy home all things considered.
In Mikes book he states that the shoring
should be 2 inches thick at least. my home wont be totally
underground so i took a risk on 1x4 lumber . also it was all i could afford lol i added some extra posts .on post about every three feet. and i may add a few more just in case they decide to bow out on my during burial.In the book he also says you could possibly go without nailing and just back fill behind the boards. i nailed them though because i will be living in it before its buried.
from what i have seen an addition needs extra posts they are a key part of the perimeter of the building.
You could defiantly use a wood floor if you like. In one of pauls cabins he has a layer of vapor barrier with wooden floor on top. Jim has one as well. as far as i know both are working great and not rotting.
from what i know about the uphill patio the one crucial part is that it is larger than your home on contort and deeper than your home. mine is deeper by a few feet and wider by a few.
walls dont always have to be buried on both sides but be aware if its not even amounts of dirt it could push the whole thing to one side. imagine a 300 pound man pushing you from the back . you fall over. add a 300 pound man to your front pushing at the same time now you dont fall over. thats the principle at least. also the ground protects you from winter could and summer heat so the less ground you got the more you have to try to insulate or compensate with heat.
I have stood in the original Royer Foyer and thats the only one i have seen. its not big i would guess actual dimensions are not that crucial as long as they fit your home. haven't seen one as a green house but i dont see why you couldn't.
i used single pain windows in my home because of price as well. actualy they are mikes windows! his family let us take some after mike passed to try to put some of his things to good use
i framed them in the middle of a 2 x 6 frame my idea is a pane one glass on the inside thats removable. the actual window . and another removable window on the outside. i did not stay the winter. but my guess is they will do just fine. we shall see.
greenhouses are normally attached to a house. there are a lot of reasons for this . most of them boiling down to
energy costs.
like i said im no expert . if you haven't gotten mikes 50$ and up underground house book i suggest you do it helped me to understand what people were talking about. all and all im glad i built PSP and i hope you enjoy your home as much as i do mine.