Greenhouse polycarbonate is a fairly recent advancement in greenhouse glazing technology.
It's a very welcome advancement, too.
Polycarbonate panels are very light and very strong
And compared to most other greenhouse glazings (except glass), polycarbonate will last a long, long time.
Polycarbonate is a type of plastic that is used in the manufacture of lots of common items.
It’s likely that you use items made of polycarbonate every day.
Phones, computers, DVDs, CDs, and lots of appliances and food storage containers are made of polycarbonate.
Polycarbonate is useful as a greenhouse glazing because it can be manufactured to be completely transparent (it’s also used to make eyeglass lenses) and very strong (it’s also used to make bulletproof windows!).
Greenhouse polycarbonate is treated to be resistant to the degrading effects of ultraviolet sunlight, which gives polycarbonate panels a long projected service life.
In fact, most polycarbonate manufacturers warrant their greenhouse polycarbonate panels for 5 to 10 years, and some for as long as 15 years. So even though it’s unlikely that polycarbonate panels will last as long as your greenhouse, they can be expected to last for many years.
Polycarbonate panels are available in corrugated sheets, or in double-wall or even triple-wall panels. The multi-wall panels help to retain heat in the greenhouse with their excellent insulating values, but still allow plenty of light into the greenhouse.
Polycarbonate is such an efficient conductor of light that a triple-wall polycarbonate panel allows more light transmission than a double-layer of greenhouse plastic film.
All of these benefits combine to make polycarbonate an excellent greenhouse glazing. But not perfect.
Greenhouse polycarbonate does come with a few disadvantages, the most notable of which is cost.
Polycarbonate glazing is far more expensive than poly plastic, which is the most popular form of greenhouse glazing (but polycarbonate is considerably cheaper than glass). You could glaze a greenhouse several times with poly plastic for less than the cost of glazing it 1 time with polycarbonate.
But that cost differential can be at least partly balanced out over the life of the greenhouse if you consider that poly plastic will have to be replaced a minimum of 3 or 4 times for every 1 time that the polycarbonate is replaced.
Another disadvantage of a polycarbonate greenhouse is that installing the polycarbonate is much more difficult than installing poly plastic sheets.
Plastic sheets can be stretched over the framework of the greenhouse and attached to the greenhouse only at the 4 sides of the poly sheet. But each polycarbonate panel must be attached individually to the greenhouse, making the job much more labor intensive than installing poly plastic.
Again, though, the job of installing polycarbonate panels will have to be done much less frequently than installing poly plastic due to the polycarbonate’s long service life.
And though polycarbonate is very strong, it’s quite susceptible to being scratched. So it must be cleaned frequently and carefully to avoid a build-up of light-blocking dust and scratches.
If it’s within your budget to cover your greenhouse with polycarbonate, it’s well worth considering.
You can save yourself the trouble of having to replace poly plastic every few years (not a fun job – particularly on larger houses).
And you could have a greenhouse that rivals a glass greenhouse in pure aesthetics, but without living in constant fear of every thundercloud that passes close enough to toss a hailstone in your direction!