Hi
@leon6 and
Nice foundation. I think the flex should be fine. PVC if you like overkill.
Are you going to insulate the outside of the foundation before you grade around the greenhouse? (2-4" hard pink insulation board). If not, I would consider using a basement sealing paint on the inside of the wall or (much better) something like BlackJack 57 rubberized coating on the outside to prevent moisture infiltration.
I like your floor: gravel, paver leveling sand, concrete bricks and sand brushed into the cracks is what I did, although I would have really liked to have installed a ground to air heat exchanger. They run a good price, and I could not dig down that far, but it makes a difference in heating and cooling. Wish I knew what growing zone you are in (Plant Hardiness Zone). There's place in your profile to put it so others know. If you don't know your growing zone, check here:
https://garden.org/nga/zipzone...
Check out the double pane windows to see UV rating. Also, clear windows can easily burn plants in a greenhouse. You'll have to plan for shade cloth. Triple pane polycarbonate diffuses the light better and is strong. Depending on the windows you were planning to buy, it may also be cheaper. You could incorporate them into your stick construction. They come in all sizes and can be cut with a variety of saws.
Roof. Yes, 45 degrees if a lot of snow in your area or a roof rake with something soft to cover the metal so it doesn't scratch the polycarb. Once again, I like triple polycarb. Greenhouse Megastore at
https://www.greenhousemegastor... has polycarb sheets. I have used GHMS for many purchases. They are reliable and I have found their customer service good. Shop around though for better pricing/shipping before you purchase.
My greenhouse is 14 x 20, so it is a similar size. (Riga XL6 distributed in the US by Exaco:
https://www.exaco.com/greenhou...) I have a fan inside that circulates the air 24/7. Nothing fancy, just one of those floor drying fans on a table at one end.
https://www.google.com/search?...
I also have the following set on a thermostat. 24" automatic intake louvre and a 20"exhaust fan. I can change the complete volume of air in less than a minute. Bought all three through a J&D distributor. Once again, shop around. Prices can vary a lot. J&D makes quality equipment. There are other good companies for this equipment as well.
FAN:
https://jdmfg.com/product/indo...
Shutter:
https://jdmfg.com/product/alum...
Thermostat Controller:
https://jdmfg.com/product/vc11...
Winter growing. I am in Zone 6b. I use an oil-filled radiator type heater on the coldest nights to stay around 40 degrees. I was fine this first winter in my new greenhouse even at temps down to 8 degrees. I also have a 425-gallon pond in my gh for a heat sink, the brick floor that absorbs heat, and Phase Chage Material Panels that store heat and release it during the night. Once again, it depends on your zone what you will need.
Look forward to hearing about your progress. Ask more questions. There are a lot of knowledgeable greenhouse growers on this forum. Some check in daily; some less often. And remember, we love pictures!
Jim
