How to build a Greenhouse
1: Introduction, Description, Position
2: Sizes, Angles, What you will need
3: Making the base
4: Making the side wall-frames
5: Making the roof sections
6: Erecting the side walls and roof
7: Making the end walls and doors
8: Making the window, The cover
Appendix 60° and 30° Angle patterns
Appendix Photos of finished project
Step 7. The windows
For the windows use 1 1/2" x 1 1/2" (45mm x 45mm) treated or natural decay-resistant lumber for the top and bottom horizontal rails and 1 1/2" x 3 1/2" (90mm x 45mm) for the side styles and middle mullions.
Angle cut the bottom of the window frame 30 degrees (the same pitch as the roof).
Make two windows as per dimensions above. Fix them in place with two butt hinges on each window screwed to the top rails of the windows and the window support plate.
Fit a window latch to each window.
Measure, cut and fix a row of blocking below the windows and in between the roof frames as shown on the above drawing.
Step 8. The greenhouse cover
Cover the greenhouse with a UV-resistant polythene (there are other options also).
Hold the covering in place by laying thin battens (strips of wood) over the polythene (ensuring the polythene is taut) and nailing the battens to the greenhouse studs, roof rafters or any other solid member.
Cover the doors and windows also.
Most hardware merchants or garden suppliers only stock the standard plastic polythene that is not UV resistant but they should be able to advise you where to get the polythene required for the greenhouse covering.
One source that might be worth looking at for cover (USA) is Tyco Plastics.
There are also other options such as acrylic sheet.