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.

Before you Buy

Do you know the company you're doing business with? Is the supplier a member of the Better Business Bureau? Do they have a record of dealing honestly? Can they refer you to satisfied customers? Is the physical address to the company available? Can you visit them at their offices? Are they a real company with a history of quality manufacturing? Are they Active Members of the AISC (American Institute of Steel Construction) Do they post any affiliation with any steel building association? Do you know what you are paying for? Does the steel building contract give line-item prices? Will you receive comprehensive set of erection plans? Are you getting written 30-year paint and 25-year Galvalume Plus® warranties? Does the contract specify 26 gauge panels? Does their roof panels include a "purlin bearing" leg? Does the roof system have an Underwriters Laboratories Class 90 rating? Are you being supplied with premium fasteners with a lifetime red-rust warranty? Will your steel building have a sculptured trim package? Are all the clips welded to primary structural components? Are the framed openings factory located? Does the supplier have the ability to engineer a custom design? Will you receive an 80+ page fully illustrated erection manual? Does the supplier have an in-house customer service department? Does the supplier actually manufacture what they sell? Do they process and produce all their drawings in-house? Do they ask you to sign a contract and pay a deposit before you know the total cost?

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.

Constructing a Large Steel Building

Have you considered all of your steel building options? There are many types of standard buildings to choose from, but they are not the only option. Buildings can be finished with a multitude of options and accessories. Your land and location will control some of the parameters of the kind of structure you need. Aside from these factors you can make the choices based on your preferences. Windows, skylights and panel styles can be individually selected to comprise a personal metal building kit.

Pre-engineered metal building plans are just the starting point from which you can select options and accessories. Configuring your building may sound like a small deal, but it determines the type building you will purchase. Not every large steel building is intended to be a large shop. When you work with the manufacturer you can customize a structure with a polished look and feel. Regard your steel metal building as a low cost alternative to traditional construction.