TrichromeFan,
I don't have any pics of digging the hole or the construction of the ug building. But when i get more time ill explain it the best i can. I have pics of the upper construction tho.
Far as rain...i don't have a problem. Once my hole is dug i construct the walls everything is 16 inches on center. Once all the walls are built I assemble down in the hole. Once assembled I completely wrap the building with 2.5 " 4' x 8' Styrofoam. than i completely wrap the building with 5 lawyers of clear 4 mill poly. Before you back fill it make sure you brace the bottom and top inside so the building does not buckle when back filling, i used 2 x 12...3 across the top 4 across the bottom. Than back fill slowly, packing the soil every 2 inches until level with old ground. Than i recover with 2 more lawyers of poly. This time 20 feet out all the way around the building. I also silicon every seam, every corner. Than inside i again place 2.5" 16" x 8' styrofoam on each wall. again cover with poly and that's all i do. I'm not all fancy like the rest of you pros...some of you fellas have insane setups!! me on the other hand I average about 118 grams per plant. I grow larger plants and only 10 per flower room. x 3. 10 per 6x6 area can be pretty packed at times. but i sure love the look of a forest!..I walk in and can disappear! lol
When digging your hole try to dig it as close as you can to your outside finished room size that way you do not have to back fill much nor disturb packed ground. My 3rd design here i went with 2x4 instead of 2x6. 2x6 is better but in my soil which is pretty sandy i do not have much push from the frost cause sand does not hold moisture. so far my 2x4 framing is holding awesome! I have not made a winter yet but have had many hard rains!! my 4th design will be 2x4 as well.
I have to get a new camera...doing this with my phone is stupid!!! But i did snap 1 quick before i left my 2nd flower room. Pic does not really do justice but you get the idea. Ill gather better pics once i get a camera and show you all how i did it for under 1000.00 :pimp: