Most steel buildings are clad with profiled steel sheets, which are available in a range of colours and finishes. There are also architectural profiles and special finishes which are available at substantial extra cost. In general, standard box-profile cladding fitted vertically, is by far the most cost-effective option.

Where an insulated building is required, composite panels, which consist of a layer of insulating foam sandwiched between two steel skins, are normally used these days – in the past, a built-up system using mineral fibre between outer and inner steel sheets, separately applied, was used; however this type of system is less thermally efficient and is less common nowadays.

When a building is to be heated to domestic or commercial levels (i.e. where people are permanently at work in it) then it needs to comply with Part L2 of the Building Regulations. This requires the calculation of the CO2 emissions, thermal performance of the building fabric and services such as heating and lighting, airtightness, and efficient energy use. These calculations must be carried out by a suitably qualified competent person, and the building must demonstrate compliance with the required criteria in all these areas.

Because much of the information required to carry out the calculations (such as details of the heating and lighting systems) is not available at the time of designing a steel building, we are unable to demonstrate full compliance with Part L2. However, our design and specification is based on materials with the U values that meet or exceed the requirements of Table 4 of the Design Standards Section 1 of Part L2A. We also follow the guidelines of the leading manufacturers of insulated panels and fixing systems in specifying, detailing and installing materials and components to ensure that the required levels of thermal efficiency and airtightness are achieved.

Where insulation is required to deter condensation, or when the building is heated only to a low level, then a thinner composite panel can be used. These buildings are exempt from Part L2 as stated in this extract from the regulations:

From Part L2A of the of the Building Regulations, Page 12.

Buildings that are exempt from the requirements in Part L

16 Examples of buildings which are industrial sites and workshops with low energy demand include buildings or parts of buildings designed to be used separately whose purpose is to accommodate industrial activities in spaces where the air is not conditioned. Activities that would be covered include foundries, forging and other hot processes, chemical processes, food and drinks packaging, heavy engineering and storage and warehouses where, in each case, the air in the space is not fully heated or cooled. Whilst not fully heated or cooled these cases may have some local conditioning appliances such as plaque or air heaters or air conditioners to serve people at work stations or refuges dispersed and not separated from the industrial activities.