Hi. I'd really appreciate some help on the next steps for my greenhouse. The foundation (see photo) is 14x22' and it's located at 4100' in NE Oregon, Zone 5a. The front of the foundation faces directly south. It, and most of the east & west sides are apx. 2' below grade and back wall is about 5' below. Before backfilling I plan on installing a French drain along the exterior. Any thoughts on rigid PVC vs the flex drain pipe? Do you recommend using some kind of coating on the foundation before backfilling?
For the floor I'm thinking of adding a few inches of gravel, then a top layer of bricks, maybe with a bit of sand to hold them, for any areas that aren't raised beds. Will try to get the height of the bricks to be just above footer height. How's that sound?
I plan on using stick construction with 3x6' double pane windows horizontally on the S. side, which should give a little over 6' of interior headspace on the low (south) side. Will also use some windows on the east & west sides.
Planning on a shed roof and using multi-layer polycarbonate. What pitch would you recommended for a fairly snowy climate at about 45ยบ latitude? And do you think it'd be good to extend the roof beyond the south wall by a foot or two to avoid rain and snow running down the south wall? Would you recommend double or triple layer polycarb and do know of any good sources for long sheets?
What do you recommend for ventilation. Summer temps are often in the 80's and sometimes 90's here. And what about winter - would it be good to include a fan to circulate air even if the outdoor vents are sealed up?
Hoping to at least overwinter some greens. Planning on including a small Cadet-type wall heater to protect against the coldest weather. (Only have 110 wired to the greenhouse so probably can't put in a stronger heater.) And if having the greenhouse partially in the earth is enough to keep the temperatures moderate in the winter I hope to be able to grow a citrus tree.
Would really welcome your thoughts and suggestions on any of the above. Thanks!
