The greenhouse above is a 10×15 that was installed for a customer. The installation took 6 hours. We have installed about 30 greenhouses so have gotten the time down. If you are installing your own there is no race with time though. If you take your time and plan the installation step by step you will make fewer mistakes.
First I like to find a fairly level spot that is going to be easy to access from your house.I have built greenhouses with every exposure, North to South East to West and any angle in between. If you face the ends North to South then the West wall can get pretty hot in the afternoon. I know there are some rules out there about orientation but I find that it’s easiest to locate it so it’s convenient to use.,so orient it any way you want.
If you are starting with a grass area I would mow the grass as short as your mower goes then put down some ground cloth and start building. I have a lot of clay so I put down some 3/4″ gravel and put the cloth over that. Don’t use plastic under the house it just causes sitting water and problems with algae and fungus growth. The ground cloth drains very well.
Next find your four corners. You can use a long tape measure to find the diagonal distance between opposing corners. After finding the corners I will dig a hole with an auger or post hole digger. The hole doesn’t need to be more than 8″ in diameter, and just over 12″ deep. The stubs that go into the holes are 24″ long and have a hole drilled at 4″ from the top. With the holes at the corners ready I will place the stubs into the them so that they are plumb and so that the top is 6″ above grade. The holes in the stubs should be about 2″ above grade and facing each other across the front of the house. Then level the front two stubs across the tops from one side of the house to the other. Now you can mix a 60pound bag of redi-mix and dump it into the holes. I then do the back two stubs leveling them across the tops also. I don’t try to level the stubs from front to back. I just run a string from front to back and pound the other stubs along that line on 5 foot centers.
Tomorrow we will discuss bolting the frame together.