The walls are a simple frame with clear plastic or glass in it. We will make the frame out of cedar or pressure treated 2 x 2's.
Measure the inside dimension between each wall stud. This needs to be exact since you want this to fit fairly tight. You can miter the corners if you like but I just butted mine at the corners.
On each of the 2 X 2's, dado a groove 1/4" wide (or whatever width your glass or plastic is) and 1/4" to 1/2" deep. Position the groove approximately 1/4" from the edge.
Next cut the plastic or glass (glazing) to fit inside the groove. I like to leave a little slop for expansion and contraction but not too much or else your glazing will fall out.
Lay out all the pieces, insert the glass and using deck screws, screw it all together. It doesn't get much simpler than that!
As you get each section done fit it into the frame to make sure it fits good. As long as you have it in place I would go ahead and screw it with deck screws. I put one screw at the top and bottom of each side and one in the middle. Repeat this with each panel until your greenhouse is completely enclosed, except for the door and roof.
Next time we will put the roof on.