1. Base metal thickness, BMT

Generally, a standard project will choose a thickness not less than 0.42 mm. BMT (base metal thickness), and in some specific projects such as high-standard powerplants, thickness will choose 0.60 mm.

2. Coating

Standard Project will choose zinc-aluminum alloy coated steel layer, top and bottom coating all together will not less than 150 g/m2 (AZ150), which affects the service life or the warranty. The manufacturer will provide up to 20 years, but if pre-painted the coating is applied, the warranty will increase to 30 years, subject to the manufacturer's conditions. (Please read more details).

3. Strength of steel

Normally, cold-rolled steel’s material strength is at 550 MPa min.yield strength or approximately 5,600 kg/cm2 (G550), but in some applications, G300 is found, not often.

4. Steel Roof profile (Good quality roof must have followings)

a. strong, not easily broken or damaged when working on roofs (walking on roofs) and not blown away by wind pressure (wind resistance).
b. good drainage capacity and no water leakage into the building (roof drainage and leakage protection). The design of the project’s roof slope is less than 5 degrees. 
c. Can be bent (roof curve) the curved shape is more popular due to the beauty and unique.
d. In case of very long roof sheets, thermal expansion (expansion of the sheets due to heat) must be concerned in terms of noise and heat reduction, additional accessories and materials must be applied such as insulation, ceiling, etc.

5. Code and performance tests

Both materials and profiles are indicating the quality of the product with standards codes and performance testing, which should have both Thai and international. If it is Thai, it will refer to the TIS standard, but if foreign countries will be Australian standards AS, Japanese standards, JIS or American standards, Europe, etc.