Another “defect” of the glass is its easy to break, in fact, the tempered glass is likely to create the so-called “cobweb effect ” giving those unsightly signs of breakage even when subjected to a little stress, this effect occurs even after only a few years installation. Nevertheless, the glass has two major defects, first of all is a very heavy material, having a specific weight of 26,490 N/m3, so it is needed an important support for the plates that guarantees the seal once occurred the installation. Regarding the load borne, a good glass canopy can support from 80 to 150 kg/mq depending on the models of cover used. A 4 mm sheet of tempered glass has an impact resistance of a force equal to 10 joule.
The treatment is used to increase the resistance, in this case it can reach a mechanical strength of 170 N/mm2, it resists to thermal shock, and in the event of breakage the fragments are little sharp.
The glass normally used in pergolas and canopies is thermally treated. The transparency of the glass is very good with a transparency coefficient ranging from 0.80 to 0.90. In this article we will try to illustrate the difference between these three materials.
Every day we face questions as: -I have to put an canopy over the door to protect it against wind and rain, which material could be the best for the cover? -I need a pergola of size 400 cm x 600 cm: I can’t decide between plexiglas, polycarbonate or glass, what are the differences between these materials? During our work experience we often answer to questions from our customers about the cover material suitable for pergolas and canopies.