The coefficient of linear thermal expansion of polycarbonate is quite high and its value equals 0,067 mm/m*oC. It is one of the highest values of this parameter among currently used construction materials
High linear thermal expansion of polycarbonate should be taken into account during the process of installation. PC sheets should be loosely, rather than rigidly installed within the profiles, which enables the expansion of the material under temperature changes. Our system of aluminum profiles is designed with regard to these conditions - in order to make a right choice, please contact us before ordering.
Roof surface temperature in winter: -25oC, in the summer: +65oC. The amplitude reaches 90oC.
If the type of polycarbonate installed on the sample roof is 3,5 m long, we have to take into account that it will expand and shrink at 21,1 mm within a year. With polycarbonate sheets of 7 m in length, the value of expansion will reach 42,21 mm!
With regard to thermal expansion of polycarbonate, some space should be left within the end profiles during installation. The space should be adjusted to the outside temperature prevailing during the process of installation - the clearance left between the PC sheet and the profile should be larger in winter and smaller in the summer. This will prevent the sheets from coming out or bulging in the future.
We would not advice to install the PC sheets in the place of old glass panes and plugging the construction with putty or silicone, because they cannot adjust to the high thermal expansion of polycarbonate. Moreover, such gaskets do not assure correct air circulation and water and steam drainage. Thus, the mere exchange of reinforced glass panes to PC sheets and silicone plugging may cause more serious problems with the skylight than the ones we faced before.
Polycarbonate sheets are at best installed within the system of our specially designed aluminum profiles equipped with special gaskets. ESKADE-SYSTEM aluminum profiles are also the most durable solution for joining the sheets together.