Misunderstanding about steel roof sheets used in projects

Misunderstanding about steel roof sheets used in projects

Choosing and buying steel roof sheets, how to choose because many roof profiles in the market with different performances.

There are many questions and concerns from customers recently; not only contractors, architects, and engineers but also project owners. There are concerned about how to choose the steel roof sheet, how to compare each profile, can be replaced it, how to install and how about the noise. So, KS Group would like to share the answers as below;

First of all, steel roof sheet or also known as metal sheets in the market has so many grades, divided by the thickness and coating of the steel roof sheet. For projects or specific designs that required high quality must concern other factors as well, see tips below for your consideration.


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.


We hope that the information above will support the choice of the steel roof sheet better.

Thank you for your trust in the use of KS Group products and services.

By KS Group

STP Engineering & Supply Ltd.