Secondary Framing

Secondary framing is created from rolled steel coated with a red-oxide primer finish in gages from 12 to 16 to provide an extremely rigid, and corrosion resistant structure. The following elements are formed as secondary framing:

Girts (walls) & Purlins (roof): These members run the length of the building providing rigidity, and a sturdy skeleton to attach the sheeting. They are rolled from steel coils 12,14 or 16-gauge steel, or thicker if needed. All girts and purlins are pre-punched for ease of assembly.

Eave Struts: This is a rolled member formed into a "C" to match the pitch of the roof. The eave strut is also made of 12, 14, or 16-gauge steel.

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.

Recommended Installation Methods of Insulation

Roof insulation rolls are cut to lengths that will cover the distance from eave to eave, leaving a one-foot overhang on each side of the building.

1) Start at the end of the building and temporarily secure one end of the roll by attaching the insulation to the eave strut with double-faced tape.

2) Pull the insulation across the purlins with the vapor barrier toward the building interior. Double-faced tape attached to the opposite end of the insulation will keep tension on the roof roll while the metal panels are being attached over the insulation.

3) Install the next roll in the same manner, making sure the rolls are stretched tight, aligned properly and closely butted.

4) Fasten tabs using one of the methods described on the following page. Any rips or tears must be covered with matching facing tape to ensure a tight vapor seal.

5) Trim excess insulation flush to prevent it from acting as a wick and moving water into the building.

Installation Overview

The metal building is rapidly becoming more popular for a variety of reasons. They can be built very quickly and are extremely low in cost. They can easily adapt to any number of external architectural treatments without restricting their interior floor planning. A primary reason for this flexibility is the development of insulation specifically designed for metal buildings. The development of advanced insulation systems with more efficient thermal performance is so advanced that it has enabled metal buildings everywhere to evolve into many of the showrooms, retail outlets, schools, offices and shopping centers we see today.

Today's high-energy costs have made insulation a critical consideration during any construction planning. An insulation system that is properly selected and professionally installed will return more on its investment than any other building component.

Insulation provides many benefits:

Improved appearance, Greater comfort, Substantial reductions in fuel and electricity costs, Condensation and noise control, Reduction of the amount of investment dollars and space needed for heating and cooling equipment.

Thermal Conductivity (K-Value)

A unit used to express the amount of heat, in BTU's per hour, that passes through one square foot of homogeneous material that is exactly one inch thick and has a temperature difference of one degree Fahrenheit between its surfaces. As the K-Value decreases, so does the amount of heat permitted to pass through the material.