Sandwich panels are categorized under different color groups based on thermal load effects.

Sandvic Panel Renkleri

Color Classes

As compared to light color panels, dark color panels absorb more heat on their surfaces. As a result, significant temperature differences (Δt) arise between the interior metal and exterior metal temperatures especially in high temperature regions. Due to this temperature difference, thermal stresses may occur which could affect the sandwich panel performance, cause corrugation/undulation on exterior metal surfaces, and even may result in detachment in the worst-case scenario.

EN 14509: 2010 standard sets out the applicable requirements.

Maximum exterior surface temperatures for color groups are determined as follows: +55°C for extra light colors, +65°C for light colors, and +80°C for dark colors. Indoor temperature inside buildings as used in calculations is determined as +20°C. While maximum allowable temperatures are used in the summer months in calculations, the assumed temperature in the winter months is determined as -20°C. Therefore, the following temperature gradients are used in calculations.

For each color group:

  • Extra Light Colors Δt = 40°C
  • Light Colors Δt = 45°C
  • Dark Colors Δt = 60°C

Dark Color Panels

Applicable Principles for Dark Color Panels Compared to light color panels, dark color panels are exposed to more thermal stress and due to such stress, they may be subject to deformation and partially lose its original form. Taking this fact into account, the designer is responsible for preventing any potential deformation and changes in form. In such cases, it is recommended to find a solution that would meet the following 3 key requirements:

  • Determination of fixing method based on the purlin distances and load bearing tables;
  • Reduction of maximum panel lengths; and
  • Taking into consideration the temperature on the site during assembly of the panels.

Supporting Structure and Fixing Method

For the design of both wall and roof panels, static calculations taking into consideration deflection and stress analyses as well as temperature parameters should be used. Even though the selected panel is to be installed on a protected side of the structure, dark color panels are recommended for application in a single span system. In multispan systems, minimal surface undulations in the central support are possible due to high thermal stress. Even though it is permitted in the product standards, such surface undulations may cause aesthetic problems. Choosing thick sheets with a thickness of 0.6 mm and above in dark color panel productions would make positive contribution to the surface performance. Unless otherwise provided in writing, Assan Panel does not provide any warranty as to the surface smoothness of dark color panels installed in multispan systems.

Maximum Panel Length

The maximum length of manufactured dark color exterior wall panels is determined to be 6,000 mm. Assan Panel does not provide any warranty as to the surface smoothness of custom panels exceeding this maximum length. On the other hand, sinus form exterior wall panels have no length limitation.

Assembly Temperature

Since the assembly of dark color panels in low temperatures would increase the stress on the panel surface, assembly in ambient temperatures below 10°C is not recommended. Unless otherwise provided in writing, Assan Panel does not provide any warranty as to the surface smoothness of dark color panels installed during the days in which the average ambient temperatures were below 10°C.