i built a 10x20 last year using
https://www.ebay.com/itm/Greenhouse-Kit-3-4-or-1-or-1-1-2-Low-Peak-Slope-Flat-Canopy-10x10-20-30-40-50/153831758508?_trkparms=aid=1110002&algo=SPLICE.SOI&ao=1&asc=20201210111451&meid=ddb411cfd92045a2bdf5a8b72f702eb8&pid=101196&rk=4&rkt=12&mehot=pf&sd=153889848675&itm=153831758508&pmt=1&noa=0&pg=2047675&algv=PromotedSellersOtherItemsV2WithMLRv3&_trksid=p2047675.c101196.m2219
this kit for 1 in conduit. I used the 10x30 kit with foot pads and side wall so that i would have 4 posts wide on my 20 foot wall due to our increased snow load. we just had a blizzard with 40 to 50 mph wind and 2 feet of heavy wet snow and the plastic stretched a bit but that's it.
i ordered 12 mil greenhouse plastic from
https://www.agriculturesolutions.co...h-clear-woven-greenhouse-film-12mil-per-sq-ft
the black plastic clip things to hold it on.
I used a screendoor I got off facebook marketplace on one end and built some simple doors that let the opposite end open fully.
I have a 2x6 rim board around the foot pads attached with 2 hole strap clamps that fit tightly. then 2 layers of heavy duty landscape fabric stapled around the rim board and its full of 3/4 black granite gravel for the floor, about 5 inches deep. it was about 20 tons. lots of heat mass. I have 18 in screw in ground anchors on each corner with aircraft cable running up to the side wall joint with a turn buckle for extra ground holding. It has withstood 80 mph winds with no damage.
On the back wall are 2 windows 2 feet by 6 feet at the top of the high side with
https://www.amazon.com/Univent-Auto...coding=UTF8&psc=1&refRID=8RWWNTS65BHKANJ7RRN5
they work great. windows are made from the clear plastic panels that Home depot sells. the north ( tall) wall is also insulated with 2 in foam panels with the radiant barrier that are fully taped with the aluminized duct tape, shiny side in to reflect heat / light into the greenhouse instead of loosing it through the back wall.
For winter I have a reclaimed bill board that is black on the back hanging along the back wall to soak up more sun. with 12 55 gal poly barrels full of water and some fans and heat tape under my feed trough planters, we have not had any trouble keeping it above freezing. last night it was 15 degrees outside and the plants were around 40 degrees. We over wintered elephants ear, herbs, and some other tropical plants.
on a sunny day when its below freezing it will still get to over 100 degrees on the green house. fans blow air through the stack of barrels and this provides some cooling during the day and heat at night. the barrels did not freeze, even when the temp was 20 below zero at night and 0 during the day with a little sun. my heat/fan setup took quite a bit of experimenting to get right, but I think we are very close to as good as it gets. The total wattage of electric heat is 700 and I was closer to 2000 watts on my first few iterations.
total cost was around 1k. i had the lumber from a pergola we took down.
i like the metal, its not intrusive at all. i also can roll up the plastic on the front and use the tractor to move large stuff around or take the planters out for summer. you will need to design in a good amount of venting, in the summer we open up the big doors, the windows and open the glass on the screen door to keep it at from getting too hot. with a soft plastic you don't have to worry as much about the angle that the roof is to the sun, with hard panels you do, because of the incident angle of reflection of the surface. also, you should carefully oriented the structure, I opted for about 8 degrees east to catch the morning sun a bit more to get it heating up during the coldest part of the day. if you live somewhere warm, you may want to choose something different.
howtospecialist.com
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