You Can Build A Cheap Greenhouse
If you want to build a cheap greenhouse you will find that the sheet plastic comes in 100-foot rolls in widths of 10½ to 20 feet. It will take two people to put it on with one tacking the plastic at one gable next to the top of the greenhouse and the other holding the roll of plastic and just releasing enough to cover three or four sash bars while pulling tightly on the roll. The first person then tacks on lath down to within 8 inches of the bottom of the strip of plastic.
The second length is placed under this 8-inch lap, so there is a lap of about 6 inches, and the second length is then tacked in the same way. If the lap is about 6 inches and the plastic is pulled tight, there is no need to seal the laps since they will stay together even in strong winds. If you want a double-layer covering—and it’s advisable—the inside layer can be attached with paper disks and tacks. Be sure to allow an inch or so between the layers for “dead air” insulation. You can arrange ventilation through doors and louvres in each end or by using doors and side drop vents.