I’m designing a small, freestanding greenhouse to build in my backyard for propagating ornamental plants and vegetables. Should I use single-pane glass or some other material for the exterior?
Chris Romberg, Gainesville, GA
Bob Daley, owner of Sundance Supply in Berkeley, California, replies: Your best choice probably would be multilayered polycarbonate. It’s easy to work with and to install, it’s virtually unbreakable, and it’s double- or triple-glazed, which means it offers good insulation from the cold and minimizes heat loss. This material also diffuses light so you won’t get any hot spots in your greenhouse. Polycarbonate comes with a 10-year warranty against yellowing or damage from hail, and it usually lasts 15 to 18 years so you won’t have to replace it very often.
If money is your primary concern, then try fiberglass. Fiberglass is considerably less expensive than polycarbonate, but not as attractive. Like polycarbonate, fiberglass is easy to assemble, but it won’t last as long without special treatment. The surface starts breaking down after several years, and the fibers will rise above the sheet and collect dirt. In order to prevent this breakdown, the fiberglass must be regularly cleaned with soap and water or coated with a relatively toxic synthetic resin. But if your greenhouse glazing only needs to last eight to 10 years, you don’t want to invest too much money in it, and single-layer glazing is acceptable, then this is the way to go.
Both of these materials work well, but they are not transparent. If you want to be able to see through your greenhouse to the plants inside, there’s nothing better than glass.