Heat Transfer

Effectively controlling temperature in a steel building requires insulation to be present along exterior walls and roof. When a temperature differential is present in an enclosed steel building, heat will work from warmer areas to colder areas until the temperature in the building has stabilized. At the point of thermal stabilization, the cooler (and heavier) air will be present at lower elevations and warmer air will be present at the roofline. The function of insulation is to help stabilize air temperature at more desirable levels. When it is hot outside, preventing heat from transferring into the building is the goal, and of course in the winter we want heat to remain inside.

Heat transfer occurs in three ways:

Conduction : Occurs in a solid or liquid when heat from one object is transferred by touch to another object. An example of this occurs when a pot on a stove will heat up by conductive heat transfer from an electric coil.

Convection : Occurs with the physical movement of air. There are two types of convectional heat movement. The first is natural, where hot air rises displacing the cold air and moving it down. The second type is forced or mechanical convection. This occurs when an object, like a fan, physically moves or "forces" the air to move.

Radiation : Occurs when an object is warmer or hotter than the air around it. For example, the sun, which is hotter than everything around it, radiates heat waves that travel through the air and is either absorbed by or reflected by the surface it comes in contact with.

Panel Profiles

Roof Panel Profiles - Our standard roof sheeting is the "PBR" panel, which is available in bare Galvalume Plus® as well as a variety of colors. Wall sheeting is available in "R" and "PBR" panel. Depending on the color and your geographic location - PBR panels may not be available for certain colors.

Liner Panels - For liner panels we offer a low-rib 29-gauge panel. Liner panels are an interior covering for the walls of a steel building. Like exterior walls, liner panel consists of 3-foot wide panels that are attached to the framing in the same manner as exterior sheeting. Full-height liners run from floor to roof. Partial-height liners typically attach to the girt at 7'4" and extend a few inches above it. Buildings with liner panels must have a base connection for the bottom of the panel (see base conditions).

Advantages - Liner Panels enhance appearance, providing a finished look for the interior. The biggest advantage is that liners protect the insulation and the outside walls. Because un-reinforced insulation facings tear easily, and even the best-reinforced materials can be damaged, liner panels are the intelligent solution to protect your investment. Although 26-gauge exterior walls can withstand a lot of punishment, a steel liner will protect your building's interior and performs at a lower cost than other wall coverings, which will require their own framing.

Insulating Against Radiant Heat

Traditional forms of mass insulation, like fiberglass, are effective in preventing heat transfer by conduction and convection, but they less effect on radiant heat. Between 80 and 90% of the radiant heat striking fiberglass will pass through or be "emitted". Radiant transfer typically has as much impact on the temperature in a building as conduction and convection. For more information on radiant barrier facings click here.

Surface Air Film Coefficient (F)

The amount of heat flow in BTU's per square foot per hour between an exposed surface of a material and the adjacent air. It is the measure of the conductance of heat through the air film that clings to all surfaces.

Frame Features

Connection Clips - Specially fabricated clips are designed to securely connect structural components. Many companies supply only blank plates that must be cut, drilled and/or welded to components before assembly can begin. In some cases it may require many hours of work to connect required clips. Metal Building Depot details and supplies each clip and placement to every building manufactured. We factory weld all clips onto rigid frames and guarantee the correct placement of all component connections. Don't waste your time and money attaching clips that should have been factory located.

Structural Bracing - Most buildings under 60' have sufficient diaphragm action or "panel shear" that provides all the bracing needed to stabilize the building. In some cases of high winds, seismic or snow loads may cause more stress than panel shear can handle, so additional reinforcement may be required. In these extreme cases we will employ the use of X bracing to reinforce the frame. In situations where X bracing cannot be used a wind column is an excellent addition to strengthen a vertical rigid frame column. A portal frame is sometimes used in extreme load circumstances. Portal frames are fairly expensive and only necessary in rare circumstances.