HelpfulGardener.com

I'm getting ready to build a greenhouse as part of an aquaponics hobby (raising fish and using the poopy fish water as fertilizer for plants growing in gravel beds). I live in Northern California, near San Francisco, but away from the fog. I've got a couple of big decisions to make and I'd love to hear from folks who know more about it than I do.

First, the greenhouse will be 10' wide by 24' long, with the long direction running 10 degrees or so east of due north (I.e. 2 minutes after noon). There are no other options for locations due to trees, fences and existing buildings. That area gets the best sun in the yard, pretty close to full sun all day long all year long. So my first question, what kind of roof? Flat? Shed? If shed, tilted what way and how much? A-frame (but the peek would be running north/south)? Any other options?

Second, I'm debating between paying for polycarbonate and doing the whole thing that way or using good quality green house 6 mil plastic. The polycarbonate wouldn't kill me price wise and I'd love to have the whole thing feel sturdy and last for a long time. The other option is looking for a bunch of used windows and making custom walls out of whatever double pane windows I can find. It sounds like a hassle, replacements could be a hassle but would it be hugely better in terms of insulation?

Third, I was reading a PDF recommended by someone here about greenhouse design and they talked through the science of roof design, but given my north/south facing, that gets tricky, and, if I used polycarbonate (the ones that look like sine waves), wouldn't that totally screw up those calculations too? I'm not too worried about getting enough heat/light during spring/fall, it's mostly about winter light, so, what is best plan to maximize that without messing up rest of year that's also reasonable to build?

Last, I'm pretty sure I'm not going to insulate the floor.The fish tanks will have insulation under and around their sides, but there will be a bunch of gravel/pavers on the floor, around 800 gallons of water (kept 75 - 80 degrees) and almost 100 cf of gravel in the grow beds that serve as a ton of thermal mass. But, I'd love to have minimal heating bills during the winter, so I'm open to suggestions for how to maximize passive solar heating.

And, always a good idea to throw out, any other suggestions/ideas folks have for great designs/features/plans for greenhouse design?


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I am sold on the A frame that is set on 2 foot border or have it dug down 2 feet from the surface! I have a small one only 8 by12 dug down a foot from the surface and its nice for a small solar water storage greenhouse to keep some plants over winter!
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The back wall I would have flake board with a covering or shingle! The shingled wall is insulated with a white or reflecive material which throws much light into the main area adding to the light intensity! My larger A frame 12 by16 has a 10 foot high peak. I even have a storage area I use in the summer to deter the intense sun! I simply use a 6 mill cheap plastic on the outside and a 4 mil clear plastic on the inside that are about 4 inches appart.
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I I have several windows with screens that wind so Ican open then when the heat is high! Ialso have storm door screens around the 2 foot border on the sun side toopn in the summer while keeping pest out! I have about 250 gallons of water inside to store heat! I made a sweat chamber on the north wall that s insulated with 2 inch styrofoam. I will maintain heat in the sweat chamber with a 30 gallon heated acquarium!
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I made the A frame out of 2bu4 4 by 10s regular lumber. The whole frame was easy to build in less than 8 hurs by myself! My temp never goes below 30 degrees all winter without any xtra heat except for the small amount of heat in the heat chamber! I have climbing beans in there now along with some tomatoes for the winter! lots of flowers and spikes I move in for the winter ! The plastic 20 by 100 can be bought at lowes for about $65 roll! I take the lower part f the plastic off every year since is so cheap and t helpcool the greenhoue in the spring !Hope this helps

My new greenhouse will be 20 foot by 8 wide. It will have 3- 4 by 6 foot 8 inch slidding double glass doors layed on the 4 foot side setting one foot off the ground making the south wall 5 feet high and 20 feet long!