Below you will see how we install one of our greenhouse kits. Some of the photos are sideways (not sure why they do that) but if you click on them they will enlarge and be straight.
Lay your arches on the ground and assemble them first. Then stand them up on the base rails.
Install the Hat Channel anywhere you like. Most people put it right under the curve of the arch but you can do it on the underside of the roof if you prefer.
Start with the front wall and the diagonal pieces first to make the front wall plumb. (this display model we set up was too small to have the diagonal pieces installed and thats why you do not see them) Then put up the ones running horizontal that you see here next to keep all the arches evenly spaced apart.
Now we are ready to install the back wall. Start at the bottom and then work your way up. You can space them as far apart as you need to fit any size vents or fans you may have purchased. These were set up about 24″ apart.
We recommend putting the bracket under the 2nd, 3rd and 4th horizontal bars for best support.
So this is what the bottom bar would look like and then you would roll it upside down when installing the next 3 bars.
The first door post going up.
Time for the horizontal pieces. Start at the bottom and work your way up as you did on the back wall. Again you can space these to fit any size vents or fans.
Thats the header bar you see above the door. Once you get your door installed, go ahead and put the header bar on where it will fit nice and still allow the door to swing without bumping the header bar.
When installing the plastic we usually install the end walls first, then trim the excess off by following the roofline with a small disc grinder with a metal cutting blade. It cuts cleaner and smoother than a pair of tin snips. In this picture you see we started on the roof first. When installing the roof always start at the peak, center the first panel front to back with the center rib, and work your way down to the ground overlapping the pieces from top to bottom.
Use the longer 2-1/2″ screws to install the trim pieces. When cutting the corners to fit you only need to cut the front side of the trim and then while holding your finger on the solid part behind it, bend it over to fit. Always remember to make your mark even with the top of the ribs of the roof line plastic. And make your cuts 90 degrees strait across.
Then put on the center piece of trim and your done.