While it is important to look at Insulation bulk, and R values, there is an often overlooked little detail that can save you a huge amount, for a tiny additional outlay. That option is ichiteck a simple thermal break along the Roof perlins.
The largest source of heat loss in a steel building is from convection. The heat loss occurs through the roof perlins, which are typically exposed, or lightly insulated on the interior of the building. Being steel, the perlin carries the heat right through the Insulation barrier to the roof cladding, where the heat is dissipated to the outside air. Because the roof insulation is compressed between the roof cladding, and the perlin, there is a minimal thermal break at this point.
The solution is to purchase a proper thermal barrier, or thermal break, and install it when erecting the building. A manufacturer supplied thermal break is very simple. It is basically a composite material, about 3/8 of an inch thick, that is a heavy duty, but inexpensive insulator. It comes with countersunk screw holes, and teck screws to secure to the outside face of the perlins. When installed, it brings your roof insulation up to it’s full theoretical value, at a cost of a few cents per square ft. of building.
The benefits of a thermal break are many, firstly it will help reduce your conductive heat loss by as much as 40% in the most extreme conditions. When mounted to your steel buildings structure will also significantly reduce the winter ice buildup on your roof and gutters. In addition it will also help to meet LEEDS certification and save thousands of dollars per year, for an initial outlay of only hundreds.