Story of Steel

Fact NOT Fiction Not all Post Frame Structures are Created Equal

Rust Protection:

Galvanizing (G) vs. Galvalume (AZ) Galvanizing: A coating based in zinc applied to steel panels to sacrifice itself for the protection of the steel. Galvalume: A coating based on aluminum applied to steel panels to sacrifice itself for the protection of the steel.


Galvanizing is a process that protects the steel from rusting. The coating is applied to the bare steel at different quantities and given a G value (G40, G60, G90, etc.) and measured in pounds per square foot of steel. The G stands for galvanizing and the number refers to the amount of zinc in the coating. Zinc is the active ingredient that sacrifices itself to protect the steel. These G factors are a bit deceiving as they refer to the total amount of galvanizing on the entire panel (front and back). Therefore, a G-90 has 1.5 times the amount of galvanizing than a G-60 for they have 45 and 30 on each side of the piece of steel. Basically, the higher the G value the better the product and you can expect a longer life. The benefit of galvanizing is the product heals itself very well. This means that the end cuts, field cuts and scratches are protected by the adjoining galvanizing.


Galvalume is also a coating that is applied to the bare steel to protect it from rusting. This coating is a combination of aluminum, zinc and silicon and is measured the same way as the galvanized coating. For instance, AZ 50, AZ 55 and AZ 60 stand for ounces of coating per square foot. So AZ 55 has .55 ounces per square foot of steel.

Galvanizing vs. Galvalume

Which is better: Galvanizing (G) or Galvalume (AZ)? Well, both have their good points. The AZ prevents edge creep better than G but it is not as good as G on scratches and end cuts. In fact, on lighter colored buildings, you can see the rust stains on the drip edges of AZ buildings. Also, AZ products do not perform well in animal confinement buildings. The finish of the AZ will often have an orange peel effect. G seems to lay flatter and there for looks smoother as a finish. We have used both and did not like the rust stains made by the end cuts so we use only G-90 standard. The benefit to you is that your building will not stain and will look better longer.

Gauge: Measure Of Thickness Of Steel

Gauge is a term that is thrown around the industry very often and in most cases the people throwing it have no idea what it means. First off, the larger the gauge number, the thinner the steel. You would think that the measure of something would be simple but this is not the case. The steel mills do not have the ability to make the exact decimal equivalent of gauge so they give themselves a tolerance range. To the right is a chart for a galvanized steel sheet that lists the gauge's decimal equivalent and the tolerances. As you can see, the range is wide and overlapping each other. Measurements should be taken of the bare steel with only the galvanizing on it. So could you roll steel .0187 and call it 26 gauge? Yes. More than likely, they are ordering a nominal .0187 and some of their steel falls into the 28 gauge tolerances. Some companies even measure the steel with the paint on to say they meet a higher gauge. This is sad but true. Most of the companies in our industry offer a 29 gauge product with a minimum thickness tolerance of .0142. We order our steel at .016 minimum and as mentioned before, the steel mills cannot keep this specification, so we end up with a steel only thickness of .0171" standard (28 gauge) with a thickness upwards of .021" including our additional galvanization and paint system. This amounts to having 20.4% more steel on your entire building. This steel does cost more. The benefit to you is a better looking panel with better performance against hail, wind and miscellaneous bumps.

Hardness of Steel – Commercial Grade vs. Structural Grade

PSI: Pounds per square inch. Commercial Steel: A soft steel that has a PSI rating in the range of 40,000. Structural Steel: A very hard steel that has a PSI rating above 80,000.

The difference between commercial and structural grade steel is as the definition above states. Commercial steel is softer. This makes the steel easier to form into panels and trim. It also dents easier. Structural grade steel is harder, therefore it is harder to form requiring it to be incrementally bent at a slower rate over a longer and much more expensive set of tooling. Once again, this steel is more expensive, however it is basically 2x stronger, can span further and doesn't dent or sag like commercial quality steel. We use structural grade steel because it performs well in hail, heavy snow and with flying debris. Our steel actually averages out to 92,000 PSI. The benefit to you is a stronger building that resists dents and keeps your building looking better longer.

Panel Shape Or Profile

Panel shape is another matter that needs discussion. Most of what we deal with is 12" on center (o.c.) spacing of the major rib. This is by far the best looking panel on the market. The 9" o.c. spacing is very busy and the building tends to have no pop.

Syfine Groove

A Syfine Groove is a small groove in steel panels that breaks the water tension and prevents the water from jumping the lap rib.

Trim Options

Many builders in the industry have up to 6 different trim options. Walters has 104 different types of trim profiles to choose from when detailing your building. Example: your gable trim is designed specifically for a gable application while your corner trim is designed specifically for a corner. The benefit to you is your building will be trimmed-out with extreme detail and your building will be aesthetically pleasing to the eye.

The Extra Cost – Well Worth It

Our steel costs $0.32 per square foot more than 29 gauge, G-60 steel. Our buildings, if you do the math below, should cost at least this much more:

This is a simple calculation and does not include the gable end. Your sales representative can give more accurate numbers. Bottom line, Walters Buildings is an investment with benefits to last a lifetime.

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