Contractors looking for a good deal on galvanized steel and aluminum roofing coil should always be careful—if it looks too good to be true then it probably isn’t.
There are some tools and “rules of thumb” for them to be sure they’re at least getting what they paid for.
Contractors order metal roofing coil by the square foot and most, in turn, charge their clients the same way.
So the number of square feet a coil is going to yield will dictate how much they are going to pay and how much they are going to earn.
There are a few unknowns in the process. Let’s use 24 gauge steel coil as our example. One coil of 24 gauge material can be different from another. That’s because industry standards permit “tolerances” in what constitutes a 24 gauge thickness. For example, we’ve know of one widely used “standard” that allows the thickness of 24 gauge galvanized steel to be anywhere from .0236 to .0316 inches thick. We know another one that only allows it to be from .0236 to .0296. A lot of contractors know this and realize that the yield of a coil may differ to some degree based on those tolerances. The only way to figure how many square feet the coil will accurately yield is to use a micrometer to measure the thickness of the material. And only a handful of large contractors and distributors have micrometers.
The differential in thickness may seem small but when you’re talking about a 500 pound coil and what it can deliver, it helps to know those fractional differences to figure how many square feet you’re going to pull out of it. Another way is to know how many pounds there are in the coil. Some big contractors will order “master coil”—rolls of 500 pounds or more–which they’ll later slit into smaller increments.
But how do they really know the coil that’s been shipped to them is actually 500 pounds. Again, most contractors do not have a scale large enough to weigh that amount.
How can a contractor tell what has truly been delivered?
There are calculators in the industry that can help to some degree. For example, we offer contractors a standing seam roofing coil calculator and a chart that can tell them how much roofing coil they have on a roll and how much coil will be required for a roofing project.
Both calculators can be found at the Englert website www.englertinc.com in the Contractor Section under Coil Purchasing. Results are for estimation only and do not include waste factors.
A contractor can choose from one of two methods to determine how much roofing coil is on a roll. The first method requires that the width, gauge and weight be known. The second requires that the coil width, inside and outside diameter and gauge be known. Contractors often do not know or have the means to find out how much the coil accurately weighs. But width, inside and outside diameter and gauge can all be readily determined.
To use the calculator to estimate how much coil will be required for a project, the contractor must input the panel profile, whether the material is steel, aluminum or copper, the roof slope factor, finished panel width and gauge.
So if you’re looking to see if you’ve gotten all the metal roofing coil you paid for there are some helpful tools out there to assist you.