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Greenhouse Question

Posted by strobe zn 7b (My Page) on
Fri, Jul 15, 11 at 10:39

I didn't see anything on the greenhouse forum to really answer this...

Does the greenhouse roof HAVE to be clear/opaque??
I've priced those polycarbonate sheets/panels and Oh My God. I've got all the materials to build except something for the roof IF it has to be clear.

I'll be building a lean-to type structure attached to the south wall of my house. I'll probably make it six feet deep and sixteen feet long. I've got cinder blocks to build the foundation and all the old windows I need. I will have to buy 2x4's but that is a small expense compared to those clear panels.

I DO have about 10 sheets of corrugated sheet metal. Could I use that for the roof?

Thanks,
Jackie


Follow-Up Postings:

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RE: Greenhouse Question

It will still be useful for some horticultural activities, for sure, but you might be limited. Think about all of the light that will be blocked: the entire N. wall, the roof, the 2x2s, maybe even by the window construction. It could almost be called a shade house, rather than a green house.

I have an alcove in my home that faces S. It has windows on 3 sides. Though it's the sunniest location in the house, it is still wholly inadequate for raising bedding plants from seed. It would be quite a different story if I didn't have a root on my house, darn it all, lol.

Have you considered using your sheet metal the first year to see how you like it? Who knows...it might be just fine for what you want to do. OR using 1/2 sheet metal? OR using a heavy grade of greenhouse plastic on the roof?

I'm sure you've already thought of this, but even with so much sun blockage, it will get really hot inside, so be sure that those windows still open, or that you construct a vent on the roof.

Anyway, Jackie, I think you'll have a lot of fun in this 'greenhouse', whatever you decide to do. Just be aware of the dramatic difference there will be between a solid roof and a clear one.


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RE: Greenhouse Question

Just wanted to throw the "alternate" suggestion out there, alternating between clear panels and the metal ones you have. Cut the cost in half and get tons more light than just metal.


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RE: Greenhouse Question

You could try using plastic sheets your first year, like rhizo suggested. Depending on what you want to grow in there (and when), a little shade could be beneficial. At my place, for example, I get so little winter sun from the hills and trees blocking the south side of my house, I would absolutely need a clear roof, but during the summer, a little shade could let me grow lettuces and other less heat tolerant crops. I think that at only 6' deep, you'd probably get enough sun for most crops in the winter, just not the real heat & sun lovers. No December tomatoes. Certainly no tender tropical trees and flowers.

If you can focus on what kind of space with your greenhouse, that may guide you better. Also -- are you willing to augment the light in the shady season with high PAR lighting?

I were going to build such a structure and it opened into my house via a window or door, I'd spend the money on a clear roof AND shade cloth to lay over it. During the winter that warm sunny space could put a significant dent in your heating bill.


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RE: Greenhouse Question

Having extensive experience with green houses, first of all you absolutely want a clear roof on the thing.Secondly you do not want it connected to your house..Why? If you are in the south heat and humidity are your enemy ! Plants love it and must have it. Your main problems will be heating and cooling the structure. Proper ventilation , pulling the hot air off at the apex of the roof and pulling in cool air at the bottom is a must.... Shade cloths in the summer if you plan to use it at that season. Evaporative cooling systems Will help in summer with cooled air and humidity. In winter the gas or electric bill will be your nemesis... Forced hot water heating is best...Good luck.


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RE: Greenhouse Question

Thanks for the fast replies!

Rhizo: yes, i thougth about the plastic and since there will the water runoff from the roof overhang, i just really dont trust it. and i was going to plan on one window on each narrow end opening and two on the front opening. and placing the door on the long wall in the middle. all this may change in an hour though :)

Nicole: hmmm, i like that idea! i dont know why i couldnt find the plastic panels yesterday on the lowes and home depot websites, but i saw them today and the price isn't so bad: $14 for one 26"x96". so i may be able to just use those. and this GH would be on the south side and there are no trees to block the sun, so it would get plenty of exposure that way... december tomatoes would be nice :). i was only planning to use it for starting seeds in the spring/fall and probably moving my house plants out there to free up some shelves inside. i dont have much space in a 600 sq' cabin. it will probably evolve into a potting shed too is one reason i want more permanent walls such as windows compared to plastic.

gruber: i think i will be able to get the clear panels after all :). and the room it will be connected to does not get heated or cooled, so no problem there.

Thanks!


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RE: Greenhouse Question

gruber, we're trying to focus on how to make a small hobby lean-to 'greenhouse' work...not something that strobe needs for production growing. I have a great deal of professional greenhouse experience, too, but know that it is possible to get a great deal of enjoyment from the most rudimentary of sun rooms.

strobe, keep us up-to-date about your plans. You've got an interested audience!


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RE: Greenhouse Question

I've been thinking about a different method. Those metal carports are everywhere you look, for prices that look affordable. Why could one not take one of those, leave the metal roof off, finish the ends with lumber or metal, and cover with a clear plastic of some sort? In all my travels and walking through tens of thousands of yards, I've never seen anybody do it.

If the frame needs the roof sections for stability, you could use them on the sides up to about three feet, and you could connect the frames at the ridge.

Add a door in the front, a window or two depending on the size, and a ventilation fan in the back. One big expense would be the covering material. Ordinary plastic doesn't last long out in the sun, but the stuff commercial growers use is quite expensive.

I'd like to build one before I get too old and too poor. :)


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RE: Greenhouse Question

I keep driving by the Don Kennedy lot on 72 looking at that walkway tunnel that used to be at Huntsville Hospital wondering if it could be adapted. It's been out there a long time... they might let it go for cheap. :)

It's probably not clear enough, but it sure looks like a big hoop house to me!


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RE: Greenhouse Question

Good greenhouse plastic can last for several years, believe it or not. It would be my choice.

Lol, alabamanicole, Robert and I have said exactly the same thing to each other about that walkway tunnel frame.


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RE: Greenhouse Question

Sundog: the metal carport would be great idea or even a metal swingset if you could figure out how to attach the plastic. but i need this greenhouse to be narrow so i'll have enough room to walk around the house and cut the grass too. there is about 25' of space between the wall and the bluff that goes down to the water.

Nicole: I've been looking at everything now. Could THIS be a GH? Oooh, could THAT be a GH?? I read one article about using a trampoline frame wall the wall framing.

I had drawn out a sketch of my plan on paper to show y'all, then I went outside with my tape measure and I have even more room than I thought I did. So it's gonna be 8 x 12 instead of 6 x 12. Back to the drawing board!


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RE: Greenhouse Question

Ok...Strobe in order to utilize your project you will ,by necessity,need to heat and cool it .There will be cold cloudy spring days when you will need heat and at night. A few days later the sun shines bright and it is 75 out side, Any where in your green lean-to higher than 6' it's 130f with low humidity with the lower air strata correspondingly high temp.
Plan on a vent fan up high on one end , if that is only a cheap box fan "rigged" to suit the situation. Heat using your imagination . CAUTION YOUR ELECTRICAL OUTLETS NEED TO BE THE GROUND FAULT TYPE AND PROPERLY CONNECTED, especially if it has a dirt floor. Good luck and Good Growing!!


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RE: Greenhouse Question

We got out there yesterday and cleared all the little mimosa trees out from around the house. And then ran into a yellow jacket nest and had to stop. The GH will start at the far end of the wall in this pic and stop right where the ground starts to slope back up and just before the windows.

(You can see the start of my chicken coop in the background. I've got lots of projects going.)

Photobucket


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RE: Greenhouse Question

gh

Ok, here's a new rough drawing with a detail at the bottom of how my house is oriented.

1. Potting bench 6' long.
2. Simple shelf over potting bench.
3. 24" door. Will either be built out of 2x4's like a dutch door for extra ventilation or I have a 24" glass door I may use.
4. Seed flats. Just guessing on the size here (1'x2'?). Laid out this way I could fit 30 on the shelves.
5. Shelves will be built probably out of 2x4's with open top and wire stretched across them. There will be one shelf at 36" high and another maybe at 60" high. I haven't worked out the roof angles so I dont if another one will fit that high yet. But, in theory, thats the way I want it. :)
6. Two windows with view of the water.

I'm still open to suggestions and opinions. :)

Thanks,
Jackie


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RE: Greenhouse Question

What are you hoping to achieve with this greenhouse? Just seed starting?


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RE: Greenhouse Question

Strobe , it looks to me like the way you have this thing oriented that the house is going to shade your your plants from the morning sun early in the spring. The vernal equinox
happens about March 20th or something like that. That means the sun will be rising about due east and setting in the due west. To have plants ready for April planting or earlier you will need to sow sooner than that and the Sun will be rising further north of east at that time of year. I'd say that the south corner would get some morning sun but that would be it
until sometime in June.


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RE: Greenhouse Question

Strobe ,disregard my last post.I got my wires crossed, It is late, The Sun will rise South of East at sowing time an you probably will be in good shape with the morning light...sorry.


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RE: Greenhouse Question

  • Posted by jcalhoun 8b Mobile County AL (My Page) on
    Wed, Jul 20, 11 at 12:49

I have never built a green house but I did use the clear plastic panels as sky lights on my garage. I placed two rows about six feet apart with the rest being sheet metal. This allowed plenty of light in the garage. I doubt you will need more than three of the panels so that will save you some cash.

The plastic panels never really fit well with the metal so a lot of silicone caulking was needed to make a seal. You'll need some anyway to cover the screw heads with so they don't leak into the wooden rafters and causing rot. The rubber gaskets on the roofing screws will dry and crack after a few years, this is why I covered them with silicone caulk (not latex).


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RE: Greenhouse Question

Nicole: Yes probably and just to have some room for my house plants. Ill have another potting bench in here too. Ill probably store all my junk pots and some tools in here too. My current potting bench is an 8' stainless steel table that is not under any kind of cover so any plants i sit out there have no protection from wind/rain/etc. I have all my tools shoved into a 6'x6' cinderblock building where my well pump is and I can barely walk in there.

JCalhoun: I had the plastic/fiberglass panels on my carport at my old house and there was plenty of light under to grow plants. I've actually found someone that has a garage full of the sheets. I'm trying to talk them out of about 10 of them :). And you're right about the alignment being off. The waves in the sheet metal are smaller than the waves in the plastic so that was my main concern for mixing them. I was going to cover every screw hole with caulk too. Water can be the enemy sometimes!

Thanks!


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