I live in the SF Bay Area and am planning to build a luxury greenhouse in my backyard. I've checked with a local architect as well as with the city planning department, and have determined that I can build a greenhouse that is up to 40x25 feet (footprint) large with walls that range from 12 feet on the sides up to 17 feet tall at the top of the roof (an A-frame roof).

This will be a significant and commercial-grade project. I plan to grow tropical plants, making it into a botanical conservatory with rare palms, plumeria, guava, mango, etc. Because of the size of this project, I'm planning to have it professionally manufactured and assembled. The greenhouse will be fully automated, with fans, automatic vents, automatic shades, heaters, irrigation misters, nighttime lighting.

I Initially looked into Hartley Botanic, but after some research realized that they only make greenhouses that look nice but don't function well. I eventually came across Florian Greenhouse http://www.floriangreenhouse.c... which seems to be a high quality manufacturer. I've read The Year-Round Solar Greenhouse book, but I'm going to rely on the company Florian Greenhouse to help me avoid major pitfalls of building a greenhouse, as they do this commercially.

In your opinion, what is something I should look out for when building this project? Do other commercial grade greenhouse manufacturers and builders come to mind?

I like your choice of builders, Florian Greenhouse. They built our attached (small ) Geneva type greenhouse in 2001 and it held up perfectly! I personally would always try to connect the greenhouse to the house if somehow possible. It is nice to walk in from the house and and functions are surely easier controlled when attached and easily accessible.

Mine was purchased through Charley's Greenhouse in Washington state. The greenhouse itself was manufactured in Canada and is connected to my house but without a pass-through door from my house. Because of where I live, it had to be engineered to withstand 130mph winds (95 is the highest in 8 years though ). San Francisco has some pretty impressive windstorms too.

The biggest problem with connecting a greenhouse to your house is the permit process. An attached greenhouse becomes a room on your house and the permits are outrageously expensive with all the "rules" and inspections that come with house building. If I had built a free-standing greenhouse, it wouldn't have needed a permit at all.

In California, I did have a free-standing greenhouse (from Charley's). It wasn't commercial size (12 x 16) so didn't need any permits at all, of course I lived in a rural area. I imagine if I had built one as big as the one you are planning or if I had been in the city, the rules would have changed.

Probably the most important consideration is the floor and drainage. Greenhouses are wet messy places. My last greenhouse had a paver floor over sand and drained down into the soil below but, it didn't have a way to get rid of debris over sills. Lots of sweeping and dust pans. My new greenhouse has a concrete floor with drains but, the drainage is into a French drain so I constantly battle trying to keep junk from going into the drain and clogging it. It would have been a much better plan to have a concrete floor slightly higher than grade with drains at floor level so the water and debris could be washed outside through the drain holes.

PS: If you do need a permit, don't add the the chair until after the City/County comes to see how much they can raise your property taxes (No they don't make an appointment but will know when you are done from the inspector). You don't want to suddenly discover you built a greenhouse but are being taxed for a patio room.

DaisyI said:Probably the most important consideration is the floor and drainage. Greenhouses are wet messy places. My last greenhouse had a paver floor over sand and drained down into the soil below but, it didn't have a way to get rid of debris over sills. Lots of sweeping and dust pans. My new greenhouse has a concrete floor with drains but, the drainage is into a French drain so I constantly battle trying to keep junk from going into the drain and clogging it. It would have been a much better plan to have a concrete floor slightly higher than grade with drains at floor level so the water and debris could be washed outside through the drain holes.

Thanks for your feedback regarding drainage, that is truly important.

The starting point is your local climate.

What parts do you want to emphasize? For instance, here at 7600 ft. in the Rockies, we have lots of sunny days, which are important in winter when the sun is low, so I chose three-wall poly with a high transmission.

What do you need to counteract? That bright sun can overheat the greenhouse, even with the automatic ventilation I use, so in summer I add reflective shade cloth to the roof and walls.

Other aspects are insulation—the concrete foundation is foam insulated with foamboard underlaying the gravel and sand floor and the roof is six-wall poly R 3.8. The thermal mass storage is helped with dark brick pavers and large black water tanks on the south-facing wall.

For winter heat, I salvaged a residential flat-plate collector and run a glycol loop with a DC pump on a solar panel that stores the days heat in a 400 gal. water tank under the floor, with the water circulated through a maze of PEX tubing, keeping the floor above 55°F even when it's -40 outside.

Because the strong and gusty winds here cause a metal-framed greenhouse to rack and the joints to loosen, and winter snowloads can collapse a kit greenhouse, I did my own design: a stick build with 2x wood framing and diagonal straps to brace. Still solid after ten years.

Posted a bunch of photos on this thread: <https://garden.org/thread/view/97158/Please-share-photos-of-your-greenhouse/?offset=60>

In the Bay Area, you'd need to maximize light, both sun transmission and grow lights. Moisture buildup would also be a problem, one I've not had. Laid drain lines for my greenhouse and it's never drained a drop of water. But you need good ventilation, possibly fan-forced, and might even look into dehumidifiers.

When I was in Sitka, Alaska, people told me they'd built greenhouses to keep off the constant rain. So local climate is definitely the crux.

Good luck!