Hi Steve,
I purchased a 10 X 12-kit greenhouse as an addition to my current green room. I think there were lots of pro’s and con’s. At the very least, it was a learning experience!
First thing you should do is research! This can make such a difference in what you purchase. The kit I bought had HORRIBLE instructions! If I had done more research, I would have found the message board dedicated to fixing the instructional mistakes created by users for that specific model. (I felt so DUMB).
Also, do research on the freight company being used to deliver. I had a nightmare with mine because many companies will not take the greenhouse off the truck. Many models weigh in the excess of 200+ pounds. You will need people or tools to get it off the truck yourself. (it happened to me lol)
Secondly, make a purchase you can live with for a while. Construction if you are doing it alone, or with little help can be exhausting. Even worse, to complete the project only to discover you have already overgrown your space.
It might mean waiting a little long to get a larger model, but it will be worth the wait.
Something else that is very important. Check with your city on the height restrictions and codes for your area. Nothing is worse, then getting all the work done, only to have a neighbor nark you out for something “they” view as an eyesore. It can happen! Then you suddenly have city officials fining you monthly, until you rip it down.
My greenhouse is 11 feet high at the top, but I live in a semi rural area, and I asked my neighbors permission to build.
There are all-inclusive kits on the market that are reasonable and sturdy. Aside from the bad directions, I really love mine. However, I live in Southern California and a lot greatly depends on your weather conditions.
If you live in a windy stormy area, I would suggest having a foundation poured before you begin. That way the structure can be bolted or secured to the site. If you are going to line in plumbing, and electricity, do it during the foundation stage. That way the pipes will be run directly up from the foundation area.
The location I picked to build already had an existing water pipe and spout. So, the greenhouse went in front of the existing pipeline. We are currently working on purchasing a solar powered exhaust fan system with a backup battery. I did not want to run electricity out there. (My current circuit panel is already maxed out) and I love solar powered things. You might consider that an option if you get good amounts of sunlight. It sure will save money in the end.
I would not build on a wood-based structure or a deck though. With high levels of water spilling and humidity, it will lead to rotten boards.
Before my greenhouse went up, we dug a 6-inch deep dug out all around the base. The interior was then filled with several layers of weed suppressant fabric. Then we shoveled in 3 inches of loose gravel. I can spray water on the floor all day with no problems.
Overall, my greenhouse took 3 weeks to build. However, I had nightmare directions, plus work and school. Sometimes we were not able to get out there too work on it for more then an hour everyday.
It was a great learning expereince though, and in the end it's worth all the trouble I think.
Good luck on your project!