There are many types of steel out there on the market but the key types used in steel buildings are hot rolled and cold rolled steel. Both types of steel are ideally suited to different purposes to understand why we need to consider the differences between the two.Creating the hot rolled steel for construction involves roll-pressing it at extremely high temperatures, making the steel easier to manipulate and work with.
Why hot rolled steel?
Hot rolled steel benefits from the following:
- A scaled surface caused by the cooling process after extreme heating;
- Minor distortions during cooling, leaving the surface with imperfect angles;
- Edges with slight rounding and corners as a result of shrinkage and imprecise finishing
Hot rolled steel tends to be use in larger buildings where a greater support and strength is needed but where there is little concern for the weight or scale of the steel being used. Typically buildings wider than 20m and higher than 6m to the eaves will need to be built with a hot rolled steel frame.
Where is cold rolled steel suitable?
To end up with cold rolled steel, hot rolled is cooled and then subjected to more rolling to create more precise dimensions and smoother surfaces. The “rolling” process can involve a wide variety of finessing techniques like grinding, polishing and turning.Cold rolled steel differs from hot rolled steel because it has:
- Better finishing and closer tolerances;
- Truer and squarer bars with great definition of edges and corners;
- Uniform and straight tubes;
- Surfaces that are smooth and oily;
Cold rolled is a better defined material and better in finesse, precision applications that need aesthetically pleasing results and often where cutting costs is eschewed for better finished results.In a construction you can find that cold rolled steel is, over time, more economical than its counterpart, especially in portal frame designs. As a result of the processing and galvanization cold rolled steel is rust protected, saving time and costs involved with treatments.Additionally, cold rolled steel frames will last for over sixty years in general without hassle or repair and as it's relatively light and the components for buildings can be put together on site saving lots of money and reducing the carbon footprint involved with transportation and installation.Cold rolled steel structures also benefit from a high strength to weight ratio, making the building incredibly strong but also lightweight. This characteristic eliminates the need for very deep foundations cutting cost and again the carbon footprint associated with construction. A 150mm deep floor slab is normally enough to support a building with light industrial use. It's ideal when constructing industrial units, storage warehouses and workshops or car show rooms that have uniform, constant and limited functions. Hot rolled is much more suited to large buildings, typically wider than 20m and higher than 6m to the eaves e.g. large warehouses, large office blocks and towers, etc.
Castle Steel Buildings can supply a range of cold rolled steel buildings in portal frame designs, as well as hot rolled steel buildings for larger requirements. Contact us today on 01302 301402 or get a quote for your own steel building direct to your inbox by filling in our quote request form here. 
John, you’ve written an interesting post! The primary distinction between hot and cold rolled steel is in manufacturing. Steel that is rolled at high temperatures is referred to as hot-rolled steel, whereas cold-rolled steel is simply hot-rolled steel that is further treated in cold reduction processes. Furthermore, hot-rolled steel has a rough surface, gently rounded edges and corners, and a non-oily surface. Cold-rolled steel has a sticky or oily sheen, an extremely smooth surface, and razor-sharp edges.