Rajesh Maheshwari, Head Technical Marketing (Coated Steel) at Tata BlueScope Steel Limited
Steel has become a universal building product due to its strength, versatility, durability and economic value. The use of coated steel for structures, roofing & wall cladding is growing rapidly because it offers a variety of benefits like aesthetic appeal and long service life. As a result of the metallic coating (zinc / aluminum / zinc–aluminum alloy) on the base steel, today's metal roof & wall panels resist corrosion and provide a service life of 20 years or more of trouble-free performance. Using coated steel for framing is an excellent method to build a building that will last for generations. These buildings look like any other and you would have to be told one had a steel frame. "Steel" buildings can be constructed in virtually any architectural style and size with many pleasing features and finishes. The result of this is out there for everyone to see with numerous examples of Industrial and commercial applications using coated steel.
Building Construction-Design flexibility with steel..!!!
When we talk of design flexibility of a building material pertaining to construction, following becomes important for its adaptation in the building design.Can this material be used for residential/industrial/commercial purposes?
Is this material suitable for all i.e. low, mid and high-rise structures?
How easy is it to use it? Can the local unskilled labour be used?
Can the small structure be self built by user?
Aesthetically how would it appeal?
Can one make fancy designs with it?
Cost wise how does it compare?
Are there choices/variants for different users with different financial capacities?
How much time does it require to build a structure with such a material?
Can the design with this material allow for easy expansion/relocation/reuse?
Can more free space possible within same buildup area?
What is its compatibility with other construction materials in same building?
And very important how easy/difficult is its maintenance?
And when one thinks of steel for building construction, its usages would be presumed primarily for the strength steel posses. It is a little difficult to consider that steel provides the design flexibility also. But then in the modern era, the innovative and very impressive buildings with steel have been in existence around the world. It would have been impossible had steel not provided flexibility in its usage. Let us discuss how does steel as building material offers functional as well as aesthetic qualities and provides design flexibility.
According to International iron and steel institute (IISI), 1/3rd of the total steel produced is consumed in construction activities and it is expected to go higher and higher. It is because of the flexibility it provides to designer and user. The very first flexibility steel provides is for primary members in the form of rolled sections v/s fabricated one i.e. conventional building v/s Pre-engineered Building (PEB)/Metal Building Systems. But when we consider coated steel sheeting, we are talking of the flexibility it provides in the form of variety of cladding profiles in multiple options in colors, paint systems, metal coatings, strengths (grades), lengths, widths, thicknesses for nearly every conceivable building design. Thus coated steel sheets offer excellent design flexibility, and contributes to energy savings through its high reflectivity, recyclability & reusability. Reduction in consumption is also achieved through usage of thinner and high strength material thereby contributing towards environment protection. Solutions are there for urban/suburban, individual, mass market in prefabricated units, customized units with high architectural design, commercial/residential, Do-it-yourself kits (with generally pre-punched service holes for electrical and plumbing). Long life and low maintenance are the driving forces behind most commercial building exterior treatments. For these benefits, of the many options available, coated steel has emerged as the roof or wall material of choice in many applications.
Design Aesthetics
Many building owners seeking long-term roofing solutions are insisting on metal roofs that offer both curb appeal and exceptional performance. Bold design that inspires and creates a lasting impression is made possible with metal. Of it, coated steel is very flexible because it can be used with various other materials to create a contemporary and stunning look." Steel can accommodate a variety of external finishes of brickwork, insulated renders, timber, tiles, and curtain walling. Steel can be easily cut to custom lengths and widths, so builders can design to varied choices. Architects and designers can employ longer spans without requiring as many structural or load-bearing walls or partitions. The result: more attractive design options, including longer floor spans, higher ceilings and larger open spaces. Roofing and walling sheets come in a range of profile shapes. Downpipes are available in square, round or rectangular profiles, and gutters in a wide range of styles, shapes and sizes. This allows flexibility in product suitable for a number of applications and designs mean even more flexibility in design with great aesthetics. Designing with metal offers perhaps the widest array of choices within the construction industry.Different Paint Systems
Paint system provides durability and life. Paint system means paint-primer-conversion coatings. The paint is the top coat and back coat. Paints types of Polyester (RMP, Super Durable)/SMP/PVDF/Metallic etc are available. Paint manufacturers have their own variants to these classes of paints. Each has its suitability with economic value to meet different requirements. Based on which, best suiting one is chosen for a design and environment.
Choice of Colors
Depending on your supplier, you can choose from standard set of colours with option of your own one. You can also choose the natural look of zinc or copper, or coatings that make metal look natural. Coated steel sheets are now available in many colours to use singly and in combinations to make designing flexible. Colour is important not just for looks; it has influence on inside comfort and environment. Thermal efficiency of building depends also on the colour of roof and wall.Metallic Coating
Depending on the life expected from the building material, the environment and activities inside, metallic coating option is exercised for corrosion protection. 55% Al-Zn coating compared to Zinc coating provides much better corrosion protection in near neutral condition (typical of most environments).Possibility of designs with curves
Flexibility of design allows for both traditional straight roof sheeting as well as innovative curved roofing designs. Coated steel with different base steel strength provides virtually limitless design possibilities. Due to its flexibility, it is capable of accommodating the double radius of the curved roof, with great accuracy of the curves. From flowing curves to precision flatness, metal is easy and economical to install. This freedom of design provides the architect and owner the opportunity to build within a wide range of styles and create an image that will endure.Variety of Roof
Designers and users have a choice of roof & wall with or without visible fasteners. Advances in technology such as the standing seam roof with no visible fasteners and leak proof warranty give designers even more flexibility for innovating with building structure and style.Options of different slope for roofs
There is choice of low slope and steep slope for roofs. In both categories of roofs, steel with highly durable metallic & paint coatings could be used and the benefits of high performance realized. It's the metal roofs which added the design element of steep slope to a building that separates them from conventional flat ones. Low slope roof are more economical, steep slope metal roofs enhances the appearance of virtually any building. Steep slope metal roofs accelerate the rate of water run-off, reduce the likelihood of a build-up of debris, mold and mildew, less likely to experience staining from acid rain or UV degradation. The durability and reliability of steep slope systems is quite long.Best utilization of Space
Larger interior spaces (high clearances and spans) without interior columns add flexibility to design & increase utility. At times this large span is a must requirement e.g. aircraft hangar. However, it could only be achieved with self-supporting steel framing system with no need for interior walls to help bear the weight of the building. With this self supporting steel frame interior walls can easily be eliminated, altered or relocated and large open floor plan created including raised ceilings. This excellent spanning capabilities offered by steel framing provides more flexibility in designing internal spaces that maximise opportunities for cross ventilation, helping to meet energy efficiency requirements.
For some things there is simply no equivalent, like roofing and walling made from lightweight, versatile and durable coated steel. Stronger and lighter as a combined material than all other alternatives, steel is giving builders and building designers greater scope to create wider rooms and higher ceilings, as well as support for innovative, non-conventional roofs that are increasingly being used to give properties a style of their own. High strength (minimum 550 MPa yield strength) coated steel are fast becoming the materials of choice because of its high strength-to-weight ratio, and the design flexibility they offers. It gives great spanning capabilities, especially with unusual shapes, and can cover a building with minimal structural support, allowing for more column free floor area. To obtain a desired design you can reduce the width of the joist but compensate with heavier gauge steel and not change the spacing of member.
Time frame Flexibility
Since steel buildings are quick to erect, the constraint of time is minimal. Frame, wall and roof made from steel can be erected quickly and easily, saving time and stress. Off-site pre-fabrication ensures dimensional accuracy and on-site erection and fixing to be fast and simple. Service holes can also be pre-punched for plumbing and electrical. Steel building has less weather-dependency (lower "down-time / construction time") can be installed in wet conditions unlike traditional materials. Swift erection of a building in steel can cut weeks off the average construction time. This way steel building provides flexibility to designers & builders as well.Design Flexibility Cost?
The variety in steel contributes to the flexibility of design for costing as well. These varied options have different cost associated with them. Steel construction offers the potential to build substantially more covered space with the same cash flow. Steel building can be built in much less time without increasing site resources, thus freeing capital and finite resources for other projects – "The efficiency of use of working capital". Offsite prefabrication increases the speed, efficiency, quality and safety of construction. It is also easy to integrate into existing structural systems. The predictability of cost and program also improves. Time related savings when specifying a structural steelwork frame compared with reinforced concrete can be 2 – 3% of overall building costs.
Components of steel roofing and walling are supplied to precise specifications so there is little or no wastage on site and the cost of debris removal. Most onsite waste can be sold afterwards as scrap that is recycled into other steel-based products. It is cost wise & environmentally good. Coated steel sheet assemblies are economical and durable under tough environmental conditions. Cost arising out of natural calamity is minimal.
Flexibility to Reuse
Steel building materials have great opportunity for re-use. At times, designers use this flexibility for new projects with new look using old material. This not only saves cost, it also reduces impact on natural resources.Flexibility to Relocate
The other great comfort of the flexibility steel building user has is that it can be relocated. This has helped many users to release costly land resource and rebuild the similar installation with much lower relocation cost.Flexibility to Expand
The benefits of steel building system are seen today, tomorrow and in the future. When you erect a metal building today, you have the benefit of cost efficiency, design flexibility, and the predictability of on-time construction deadlines. Tomorrow, your benefits continue with minimal maintenance requirements. In the future, as your business flourishes or your needs change, the building is comparatively easy to expand and update.Flexibility to use Local Labour
On-site construction of steel building is easy, highly efficient and safe, which an untrained personnel, can quickly learn. There is not much measuring, cutting or wet processes and the pre-manufactured fit-out can be integrated with interior and exterior fittings using local labour. Workers can be easily trained to use steel building systems in combination with other materials as well.Conclusion
Steel is such a versatile material that every object we see in our daily life has used steel directly or indirectly. There is no viable substitute to steel in construction activities. Steel remains and will continue to remain logical and wide choice for construction purpose, environmentally also, as much of the steel used is recycled.Steel building offers more design and architectural flexibility for unique or conventional styling. Its strength and large clear spans mean the design is not constrained by the need for intermediate support walls. As your requirements changes over the years, you can reuse, relocate, & modify the structure.
Coated steel sheets come in a range of styles, sizes and colour combinations, and can usually be customised to suit specific weather conditions. It is a reliable and long life cladding material suitable for a range of residential, commercial and industrial applications in almost any style of building, from modern to traditional, from big establishments to small and in almost any chosen shape or design. In addition to this, it can be used easily with other materials, a diverse range of options to choose from. The strength and flexibility of the steel products enables the construction of buildings/structures that can better withstand challenging environmental and meteorological conditions, including hurricanes, earthquakes, and high variability in humidity and temperature.
