Gonmon's DIY Greenhouse Plans

[DavidCampen]

A 4' bench depth is too much, you won't be able to reach things in the rear.

[Gonmon]

Well, ya... I wouldn't be able to reach things way at the back. the bulk containers are 39" wide, which is why the benches are so wide. Instead of IBCs I could use 55 gallon drums, but they don't use the space as efficiently, and it would be hard to connect them together if I wanted to use them to store watering water. The IBCs have 2" bungs at the bottoms, so it would be easy to plumb them all as one, and put a pump on there. I looked at having two 30" tables along the North and South sides, and a 48" table in the middle, separated by 24" aisles, but then the greenhouse would need to be at least 13' wide, and I'd lose out on space having a second aisle. Which I wouldn't be able to get to anyway with two 48" tables...

So many decisions

[fotofashion]

When DH designed my present GH, he did not consult with me so he built it like your solar design. I absolutely HATE it. It is a big waste of space. When I lived up north (In MI) my GH was a conventional shape. The walls were about 5 or 6' high. We covered it with fibreglass panels and double insulated it with sheet plastic (no polycarbonate then) eventually heated it with natural gas. I had benches made of 2x4's with hardware cloth. Pass 20+ years and an altogether different climate-Texas Gulf Coast. And--the "solar" shape GH. The trouble is that the sloping north side wastes space. I like to hang as many plants as I can. My benches now consist of the plastic shelves you can buy at any "big box" store. They aren't too deep so I can reach my plants easily. What I really need is a new GH that is a bit bigger. My present one is 12' x 16'.
Anyhow, my point is that you need to consider how the shape of the GH will restrict or extend the capacity.
I find that treated 2x4's are adequate for the structure (even in MI where we had a lot of snow).
I have 3 reinforcing rods that run back to front up high to hang plants from in addition to the benches. My ventilation system consists of an intake shutter down low near the ground at the end opposite the door and an outlet shutter + fan above the door controlled by a temperature control and a large box fan that runs 24/7. Even so the temps get up to 115 + sometimes.
I hope my rambles give you something to think about and I hope that eventually you get the GH you need and deserve.
Beverly A.

[Gonmon]

Originally Posted by fotofashion

When DH designed my present GH, he did not consult with me so he built it like your solar design. I absolutely HATE it. It is a big waste of space. ....The trouble is that the sloping north side wastes space. I like to hang as many plants as I can. ...Anyhow, my point is that you need to consider how the shape of the GH will restrict or extend the capacity.
I find that treated 2x4's are adequate for the structure (even in MI where we had a lot of snow).
Beverly A.

Thanks for your info Beverly. I went into my sketchup and measuring from the midpoint of the South bench, the roof is only 2 feet up.... Which is a bit short for anything buy seedling flats maybe. Did you mean that the sloped South side wastes space? In my plan the steeper side faces South, the North side extends 4.5 feet above the benches before sloping. I too like to hang my plants in baskets or mounts. Since I want to breed stanhopea relatives and miniature other stuff, I want as much basket/mounting space as I can get.

I wonder how much more heat the a Solar South side adds over a convential shape... If I raised the South wall just 2 feet over bench height it would give a lot more vertical grow space on that South bench. I'll have to go play around more and see if that's an option.

I use 2x6's for the supporting members so I can fit 6" thick insulation versus 4". If I remember right 4" fiberglass bats are 14 or 15 R-value, while 6" are 20. I want to conserve heat as much as I can because with my weather that is going to be the biggest operating cost. The cost of building with 2x6's vs 2x4's is small enough that it will pay for itself in a year or two.

I'm also rethinking the benches too. If I bought/built shelves like a lot of people here use, that adds a grow space I can use for lower light plants. I guess it's a tradeoff of water storage for heat savings, or more plants. That's not really a hard choice is it?

[fotofashion]

In my GH the north side is sloped and that, of course, is the space waster. The south side wall is about 5' high. I can hang plants all the way down the rafters to the wall and still have room on the benches. The peak is probably about 10' +. I have to use a short ladder to hang the plants from the re rods.
Here, the winters are relatively mild so a couple of electric heaters do the job on cold nights. It has gotten down to around 32 inside, especially last winter when we had a really cold one. But even Phals were not harmed.
As an aside, in MI when we first built the GH, it was covered with polyethelene. It used to keep me awake nights snapping up and down with the winds and me thinking that it was about to tear. Never did though. The next winter we had the fibreglass panels.
I understand your concern about space vs. economizing on the heating costs. Are you considering buying the polycarbonate panels that will give you the maximum insulating value? I know they are more expensive but if they will lessen your heating costs it would be worthwhile to consider them.
Winter is not that far away for you. You need to get cracking on your new GH so you won't get caught building it while it is snowing.
Beverly A.

[DavidCampen]

I really like these wire shelves:
Regency NSF Epoxy Green Wire Shelves and Posts - The WEBstaurant Store
They are galvanized, epoxy coated and so are supposed to be suitable for wet environments.

I bought shelves 4' wide and 2' deep with 4 shelves on 86" posts. The bottom shelf is used for supplies.

[msaar]

A few comments (re solar scheme):
-You don't mention terrain. Is your site flat or sloped? If flat, you will have to consider control of ground water. do you know where the water table is? If your site is sloped, which way? Are you planning steps?
-While the water will store a specific amount of heat, a lot of factors will affect the absorption and release of that heat: the volume:surface area of the water mass, the material of the water containers, the exposure of the surface area of the water mass to free air and sun. Your cube-shaped water tanks present concerns on those accounts.
-You will need a means of removing watering water from the GH-sump pump, drain to grade, etc.
Food for thought....

[Gonmon]

Originally Posted by fotofashion

...I understand your concern about space vs. economizing on the heating costs. Are you considering buying the polycarbonate panels that will give you the maximum insulating value? I know they are more expensive but if they will lessen your heating costs it would be worthwhile to consider them.
Winter is not that far away for you. You need to get cracking on your new GH so you won't get caught building it while it is snowing.
Beverly A.

Twin-wall polycarbonate panels aren't worth it in my application. These: Polycarbonate Panel, 10mm Clear - Polycarbonate Panels | Greenhouse Megastore, have an R-value of 1.89. A layer of inflated double poly has a R-value of 1.7 (R-value & U-value). The polycarbonate panels cost $64.44 for a 4'x8' sheet, polyethylene is $78 for a 12'x55' roll. The South face in the above plan measures 10'x21'. I would need 8 polycarbonate panels at a total cost of $515, or one roll of polyethlyene at a total cost of $78. That's a difference of $437. The polycarbonate has an R-value only .19 better than the film. Plugging that into my heatcalc spreadsheet, worst case scenario it would costs me $38 more per year to heat the greenhouse if the South wall were covered in polyethlyene. It would take 11.5 years for the polycarbonate to pay itself back. Plus I wouldn't be able to remove the polycarbonate during the summer for ventilation.

Even the panels with the highest R-value, 16mm Polycarbonate, Clear - Polycarbonate Panels | Greenhouse Megastore, wouldn't be worth it. They have a R-value of 2.36 and cost $130 for a 4'x10' sheet. I'd need 5 of those, for $650. The difference in R-value is .66. Which saves $107 a year. It would take 5.5 years to pay for itself. Which is better except I don't plan to use this GH for that long.
Hey I got a good 2 months yet before there's a chance of snow. How long could it take to build an itty bitty greenhouse like this

Originally Posted by DavidCampen

I really like these wire shelves:
Regency NSF Epoxy Green Wire Shelves and Posts - The WEBstaurant Store
They are galvanized, epoxy coated and so are supposed to be suitable for wet environments.

Hey I like those too!. I hadn't thought too much on the shelves, I was going to build them myself out of wood and hardware cloth, but those pre-made wire shelves would be a lot sturdier and not cost much more. Did you buy them from that website?

Originally Posted by msaar

A few comments (re solar scheme):
-You don't mention terrain. Is your site flat or sloped? If flat, you will have to consider control of ground water. do you know where the water table is? If your site is sloped, which way? Are you planning steps?
-While the water will store a specific amount of heat, a lot of factors will affect the absorption and release of that heat: the volume:surface area of the water mass, the material of the water containers, the exposure of the surface area of the water mass to free air and sun. Your cube-shaped water tanks present concerns on those accounts.
-You will need a means of removing watering water from the GH-sump pump, drain to grade, etc.
Food for thought....

I'm glad you asked. The site I'm looking at right now is about 50' away from the house. It's close to our satellite dish, which has an underground line (18" deep) for elec to it, I can run another one for the GH easily. I would have to put in a line for water 48" deep, and for propane if I tied it in with the house. The area is at the top of a hill. Eastwards is flat, to the South is gradually slopes downwards. To the North it is level for 20' behind the wall of the GH, then slopes down steeply. And to the West it slopes steeply. Where the greenhouse would be, it wouldn't slope N-S, but E-W the West end is ~18" lower. I was going to pile excavated soil around the West end to make it a bit more level. If I don't sink the GH 3', I'll need to level the site before building. My dad owns a tractor with a backhoe and grading blade.

It is true that large bodies of water isn't the most efficient way of storing heat. The hot water will rise and there will be a gradient of hotter water over cooler water. This reduces solar gain of the hotter water at the surface, which is where the sun usually hits it. Large water bodies also don't release the heat as fast compared to smaller containers. But over a 10hr night, it shouldn't be a big difference. The Solar Greenhouse Book suggests stacking small containers, like milk jugs, against the back wall. When stacked on their sides, the jugs contact each other well and transfer heat readily throughout the entire water body. But without a good source for a couple of thousand milk jugs, I opted for 55 gallon drums and IBCs.

[Gonmon]

Originally Posted by msaar

-You will need a means of removing watering water from the GH-sump pump, drain to grade, etc.
Food for thought....

Sorry I missed this one. I'll have the earth of the floor sloped to a drain pipe running under the greenhouse wall and outside. Then pea gravel covering the floor, maybe with concrete or paver walkways.

[DavidCampen]

Yes, I bought the wire shelves from the Webstaurant website. Shipping was expensive. It would have been better to find the product locally but I was lazy. If you will take chrome color instead of green then many places have this type of wire shelf.

I have purchased a lot from GreenHouseMegaStore. Another place with a lot of good construction materials is:
Industrial Ceiling Fans, PEX Tubing, Stainless Steel Fasteners, Industrial Machinery Storage Buildings from TekSupply
I used a lot of stainless steel screws that I bought there.