The metal sheet is the material we have been hearing for more than 10 years and is still popular until now, but why the price is so different. From more than 30 years’ experience in this business, as a manufacturer and distribution of premium quality steel products, there are many questions from customers about this, so we will share our experiences to help you make the buying decision because it is hard to find the good stuff with cheap price but only have valued product with reasonable price.
What you should know before buying:
1. Profile – depends on your favorite, there are many types, styles, color and patterns
2. Thickness – base metal sheet which mostly uses with roofing has the thickness at 0.3 – 0.7 mm, but in the project standard it will be specified the Base Metal Thickness (BMT) at 0.42 mm. If it coated steel base with Aluzinc/Zincalume (coating AZ150), the total thickness will be 0.47 mm. If it coated with pre painted coated, the TCT will be 0.50 mm. So, you need to specify the right thickness, just a little different in thickness can affect to the strength of profile ability. In the middle to low-end market, it mostly uses the less thickness and thinner coating because it will be cheaper
Metal Sheet Specification, you can read more information from these articles "The Steel Roof, an Interesting Choice" and "Which roof profile is suit for the factory?"
3. Material Specification
3.1 Strength of Steel – In the most project, it will specify the Strength of Steel G550 (550 MPa, High strength of steel) but not much finding G300
3.2 Corrosion Resistant – It is affected to steel material warranty which indicating the long lifetime, so the customer should ask for the warranty certificate from the metal sheet manufacturer
In project standard, it will specify unpainted Aluzinc/Zincalume coating with (Aluminum Zinc Alloy-coated steel) 150 gram per square meter (AZ150) which has maximum 20 years warranty. In the case of Colorbond/Colornexgen pre painted coated steel, it is the high-quality color coating on the Aluzinc/Zincalume coated steel which has the maximum 30 years warranty
- In the middle level to low-end market, it will use the thinner coating which is 70-100 gram per square meter. The warranty year will be lower to 5-10 years accordingly
- The Galvanize/zinc coated steel using for site camp will have the thinner layer which lower than 70 grams per square meter, so it is so cheap
3.3 Material Quality - standard – There are various steels nowadays both imported and in-house steel, so don’t forget to check the TIS standard of the cold rolled steel. If it is the Zincalume coated steel, it will be referred to TIS standard 2228 and TIS standard 2753 for the pre painted color coated steel. In the project standard, it will also refer to the international standards such as Australian Standard AS, Japanese Standard JIS, European Standard or American Standard etc.
4. The quality of roof indicating the ability and strength of the roof sheet in various ways such as:
- Profile Performance (to resist the foot traffic loading) - the allowable support spacing depends on the roof profile and the thickness of the steel which the purlin spacing will be getting from calculation and testing, normally spacing will be at 1.50 meters but some projects might use 2-3 meters
- Wind forces on roof (not blown away) – the wind load must be getting from the engineering test with warranty certificate
- Waterproof (well-drainage for roof length and anti-leakage into the building)
- Others such as available to curve low slope roofing, and rolled-form continuously sheet without end-lapping (depends on the fixing method). To save time and cost.
5. Product Inspection – It is the product inspection before sending out of the factory. The customer can notice it from QC Pass or product inspection form. This is to inspect the tolerance of profile and equipment in every dimension as in depth, width, thickness, and curve etc. including to the nice packaging and delivery to the customer. It is useful for the customer to inspect the product in case of the future problem.
6. Installation Quality – Even you have the good quality product but bad installation may reduce the efficiency of the roofing system. So, you should seek for the qualified expert roof installer who aware installation and of safety to get the neat, strong, nice, and durable installation.
Please consider the main 6 points as mentioned above to get the qualified steel roofing with reasonable price making the building lasting for many decades by getting the strong roof to protect the building from sunlight, rain, and wind, and also having the engineering safety and look nice.
Be aware of what you choose, you might not know the equality of the product by just taking a look. Therefore, don’t forget to check the necessary specifications from the manufacturer before buying. We will give you the price in deep details in the following article because there are various roofing systems such as the width and height of the roof profile, the quantity roof sheets per area, and the installation equipment.